Mock Exam 14
MRCOG Part 1 — Simulated Paper 1
100 mixed SBA (single best answer) and MBA (multiple best answer) questions simulating MRCOG Part 1 Paper 1. Covers all syllabus topics proportionally. Includes detailed explanations.
Q1 [SBA] (Anatomy) — A 32-year-old woman undergoes a vaginal hysterectomy. During dissection of the vesicovaginal space, a structure is encountered running along the lateral vaginal wall approximately 2 cm above the introitus. Which nerve is most at risk of injury during dissection in this region? A) Ilioinguinal nerve B) Genitofemoral nerve C) Pudendal nerve D) Perineal branch of posterior femoral cutaneous nerve E) Nerve of Okazaki
Answer: C
The pudendal nerve travels in the pudendal canal (Alcock's canal) on the lateral wall of the ischiorectal fossa. Its terminal branches, including the dorsal nerve of the clitoris and the perineal nerves, run along the lateral vaginal wall near the introitus and are vulnerable during deep lateral dissection in vaginal surgery.
Q2 [MBA] (Anatomy) — Which of the following statements regarding the blood supply of the female pelvis are CORRECT? A) The ovarian artery arises directly from the abdominal aorta below the renal arteries B) The uterine artery crosses the ureter approximately 2 cm lateral to the cervix C) The vaginal artery is a terminal branch of the internal iliac artery in most women D) The anastomosis between ovarian and uterine arteries occurs at the cornua of the uterus E) The middle rectal artery is a branch of the inferior mesenteric artery
Answer: A, C, D
The ovarian arteries arise from the anterior aspect of the abdominal aorta just below the renal arteries (L2 level). The uterine artery crosses above the ureter ("water under the bridge") 2 cm lateral to the cervix at the level of the internal os. The vaginal artery typically arises from the anterior division of the internal iliac artery. The middle rectal artery is a branch of the internal iliac artery, not the inferior mesenteric.
Q3 [SBA] (Anatomy) — During a dissection of the female perineum, a structure is identified that occupies the urogenital triangle, is pierced by the urethra and vagina, and is composed of skeletal muscle arranged in a figure-of-eight pattern around these orifices. This structure is the: A) Perineal membrane B) Bulbospongiosus muscle C) Superficial transverse perineal muscle D) Compressor urethrae E) Ischiocavernosus muscle
Answer: B
The bulbospongiosus muscle surrounds the vaginal introitus and urethral orifice in a figure-of-eight configuration. In females, it covers the vestibular bulbs and Bartholin's glands. It contracts to narrow the vaginal introitus and assists in clitoral erection. The perineal membrane is a fibrous sheet, not a muscular sphincter-like structure.
Q4 [SBA] (Anatomy) — A 58-year-old man presents with a painless, firm nodule in the right testis. A radical inguinal orchiectomy is performed. During dissection of the spermatic cord, which structure lies POSTERIOR to the other contents within the cord? A) Vas deferens B) Testicular artery C) Pampiniform plexus of veins D) Cremasteric artery E) Genital branch of the genitofemoral nerve
Answer: A
Within the spermatic cord, the vas deferens is the most posterior structure. Anteriorly lie the testicular artery, the pampiniform plexus (which surrounds the artery), the cremasteric artery, the artery to the vas, the genital branch of the genitofemoral nerve, and the lymphatics. This posterior position protects the vas during hernia repairs and orchiectomy.
Q5 [MBA] (Anatomy) — Which of the following structures pass through the greater sciatic foramen ABOVE the piriformis muscle (suprapiriform compartment)? A) Superior gluteal artery B) Superior gluteal vein C) Superior gluteal nerve D) Inferior gluteal nerve E) Sciatic nerve
Answer: A, B, C
The superior gluteal vessels and nerve exit the pelvis through the greater sciatic foramen above the piriformis muscle. The inferior gluteal nerve and vessels, along with the sciatic nerve, the posterior femoral cutaneous nerve, the nerve to obturator internus, and the pudendal nerve, all exit below the piriformis (infrapiriform compartment).
Q6 [SBA] (Anatomy) — A 45-year-old woman with stage IV endometriosis undergoes laparoscopic excision of a deep infiltrating nodule in the rectovaginal septum. Postoperatively, she develops urinary retention with loss of sensation over the perineum but preserved sensation over the medial thigh. Which nerve has most likely been injured? A) Pelvic splanchnic nerves (S2-4) B) Obturator nerve C) Femoral nerve D) Pudendal nerve E) Iliohypogastric nerve
Answer: D
The pudendal nerve (S2-4) provides motor innervation to the external urethral sphincter and sensory innervation to the perineum. Injury results in perineal sensory loss and urinary retention. The pelvic splanchnic nerves carry parasympathetic fibres for detrusor contraction — their injury causes retention without perineal sensory loss. The obturator nerve supplies the medial thigh.
Q7 [MBA] (Anatomy) — Which of the following muscles form part of the pelvic floor (levator ani complex)? A) Pubococcygeus B) Iliococcygeus C) Obturator internus D) Ischiococcygeus (coccygeus) E) Piriformis
Answer: A, B, D
The levator ani complex consists of three muscles: pubococcygeus (the most anterior, including pubovaginalis and puborectalis components), iliococcygeus (the intermediate portion), and ischiococcygeus (also called coccygeus, the most posterior). Obturator internus and piriformis are muscles of the pelvic sidewall and posterior pelvic wall respectively, not part of the pelvic floor.
Q8 [SBA] (Anatomy) — A 60-year-old woman undergoes a right modified radical mastectomy for breast cancer. Postoperatively, she notices that the medial aspect of her right arm and the axilla are numb. Which nerve was most likely affected during the surgery? A) Long thoracic nerve B) Thoracodorsal nerve C) Medial pectoral nerve D) Intercostobrachial nerve (lateral cutaneous branch of T2) E) Medial antebrachial cutaneous nerve
Answer: D
The intercostobrachial nerve, the lateral cutaneous branch of the second intercostal nerve, provides sensory innervation to the axilla and the medial aspect of the upper arm. It is frequently divided during axillary lymph node dissection, causing a well-recognised area of numbness. The long thoracic nerve (C5-7) supplies serratus anterior and its injury causes winging of the scapula.
Q9 [SBA] (Anatomy) — In the male, the corpus spongiosum of the penis surrounds which structure throughout its length? A) Dorsal artery of the penis B) Deep artery of the penis C) Spongy (penile) urethra D) Bulbourethral gland duct E) Superficial dorsal vein
Answer: C
The corpus spongiosum surrounds the spongy (penile) urethra from the bulb of the penis to the external urethral orifice, where it expands to form the glans penis. The deep arteries of the penis run within the corpora cavernosa. The dorsal artery and superficial dorsal vein run on the dorsum of the penis outside the tunica albuginea of the corpora cavernosa.
Q10 [MBA] (Anatomy) — Which of the following structures are found within the broad ligament of the uterus? A) Fallopian tube (mesosalpinx) B) Ovary proper ligament of the ovary C) Uterine artery D) Round ligament of the uterus E) Pampiniform plexus
Answer: A, B, C, D
The broad ligament contains the fallopian tube (within the mesosalpinx), the ovary (attached via mesovarium), the round ligament of the uterus (within the anterior leaf), the uterine artery and veins, the ureter (runs in the parametrium at the base), and the proper ligament of the ovary. The pampiniform plexus is a structure of the spermatic cord in the male, not found in the female pelvis.
Q11 [SBA] (Anatomy) — During a cadaveric dissection of the extraperitoneal pelvis, a tubular structure is identified crossing the pelvic brim at the level of the sacroiliac joint, running medially and anteriorly to enter the base of the broad ligament. It is crossed superiorly by the ovarian vessels near the pelvic brim. This structure is the: A) Ureter B) Uterine artery C) Round ligament D) Obturator nerve E) Internal iliac artery
Answer: A
The ureter crosses the pelvic brim at the bifurcation of the common iliac artery (level of the sacroiliac joint), runs along the lateral pelvic wall, and at the level of the ischial spine turns medially and anteriorly to enter the base of the broad ligament. The ovarian vessels cross the ureter superiorly near the pelvic brim. This course makes the ureter vulnerable during pelvic surgery, especially during ligation of the infundibulopelvic ligament.
Q12 [SBA] (Anatomy) — The lymphatic drainage of the cervix uteri primarily terminates in which group of lymph nodes? A) Superficial inguinal nodes B) Deep inguinal nodes C) External iliac and obturator nodes D) Para-aortic nodes E) Sacral nodes
Answer: C
The cervix drains primarily to the external iliac and obturator (internal iliac) lymph nodes. A smaller proportion drains to the common iliac and sacral nodes. Para-aortic nodes receive drainage from the ovaries and upper uterus (via infundibulopelvic ligaments). Inguinal nodes drain the vulva, lower vagina, and perineal skin.
Q13 [MBA] (Anatomy) — Which of the following nerves carry parasympathetic fibres to the pelvic viscera? A) Pelvic splanchnic nerves (nervi erigentes) B) S2 ventral ramus C) S3 ventral ramus D) S4 ventral ramus E) Lumbar splanchnic nerves
Answer: A, B, C, D
The pelvic splanchnic nerves (nervi erigentes) arise from the ventral rami of S2, S3, and S4. They carry preganglionic parasympathetic fibres to the pelvic and hypogastric plexuses, providing motor innervation to the detrusor muscle (bladder emptying), rectal motility, and erectile tissue. Lumbar splanchnic nerves carry sympathetic fibres.
Q14 [SBA] (Anatomy) — A 28-year-old woman is diagnosed with a Bartholin's gland abscess. Incision and drainage is planned. Through which muscle must the incision pass to drain the abscess effectively? A) Perineal membrane B) Bulbospongiosus muscle C) Superficial transverse perineal muscle D) Ischiocavernosus muscle E) External anal sphincter
Answer: B
Bartholin's glands (greater vestibular glands) lie deep to the posterior aspect of the bulbospongiosus muscle, one on each side of the vaginal orifice, within the superficial perineal pouch. An abscess must be drained through a mucosal incision in the vaginal vestibule, and the incision must penetrate the bulbospongiosus muscle to access the gland cavity.
Q15 [SBA] (Anatomy) — The inguinal canal in the male contains the spermatic cord. Which layer of the abdominal wall forms the innermost covering (internal spermatic fascia) of the spermatic cord? A) External oblique aponeurosis B) Internal oblique muscle C) Transversus abdominis muscle D) Transversalis fascia E) Extraperitoneal connective tissue
Answer: D
The internal spermatic fascia is derived from the transversalis fascia at the deep (internal) inguinal ring. The external spermatic fascia comes from the external oblique aponeurosis at the superficial ring. The cremasteric fascia and cremaster muscle come from the internal oblique muscle and fascia. The layers of the cord directly reflect the layers of the abdominal wall evaginated during testicular descent.
Q16 [MBA] (Reproductive Physiology) — Which of the following hormonal events are CHARACTERISTIC of the late follicular phase of the menstrual cycle? A) Rising oestradiol levels from the dominant follicle B) A positive feedback surge of LH triggered by oestradiol >200 pg/mL for >48 hours C) Inhibin B levels reaching their peak D) Progesterone levels beginning to rise from theca interna cells E) FSH levels showing a mid-cycle surge coincident with LH
Answer: A, B, C
In the late follicular phase, rising oestradiol from the dominant follicle exerts positive feedback on the hypothalamus and pituitary once levels exceed 200 pg/mL for 48 hours, triggering the LH surge. Inhibin B, produced by granulosa cells of the developing follicle, peaks in the late follicular phase. Progesterone only begins to rise just before the LH surge (from luteinisation of granulosa cells), not earlier. FSH shows a small surge but it is blunted compared to LH.
Q17 [SBA] (Reproductive Physiology) — Sperm capacitation in the female reproductive tract involves all of the following EXCEPT: A) Removal of cholesterol from the sperm plasma membrane B) Increased intracellular calcium influx C) Hyperactivation of flagellar motility D) Acrosome reaction completion before zona binding E) Exposure to bicarbonate ions in the fallopian tube
Answer: D
Capacitation involves cholesterol efflux, increased membrane fluidity, calcium influx, and hyperactivated motility. The acrosome reaction is a subsequent, separate event that occurs AFTER sperm binding to the zona pellucida — it is triggered by ZP3 glycoproteins. Capacitation primes the sperm but the acrosome reaction must not occur until zona binding is achieved.
Q18 [SBA] (Reproductive Physiology) — At which stage of meiosis is the oocyte arrested at the time of ovulation? A) Prophase I B) Metaphase I C) Anaphase I D) Metaphase II E) Telophase II
Answer: D
The primary oocyte is arrested in prophase I (dictyate stage) from fetal life until the LH surge. At ovulation, the oocyte has completed meiosis I and extruded the first polar body. It is then arrested at metaphase II. Meiosis II is only completed if fertilisation occurs, with extrusion of the second polar body. The oocyte is not arrested at metaphase II until ovulation has occurred.
Q19 [MBA] (Reproductive Physiology) — Which of the following changes in maternal cardiovascular physiology are NORMAL during a singleton pregnancy at term? A) Cardiac output increases by 40–50% above pre-pregnancy values B) Systemic vascular resistance decreases by approximately 40% C) Heart rate increases by 15–20 beats per minute D) Plasma volume increases by approximately 50% above non-pregnant levels E) Mean arterial pressure increases in the third trimester
Answer: A, B, C
Cardiac output rises 40–50% by the third trimester due to increases in both stroke volume and heart rate. Systemic vascular resistance falls by approximately 40% due to progesterone-mediated vasodilation and the low-resistance uteroplacental circulation. Heart rate increases by 15–20 bpm. Plasma volume expands by 40–50%. Mean arterial pressure typically decreases in the second trimester and returns to near non-pregnant levels in the third trimester, but does not exceed non-pregnant levels in normal pregnancy.
Q20 [SBA] (Reproductive Physiology) — During implantation, the trophoblast differentiates into two layers. Which layer is responsible for the production of human chorionic gonadotropin (hCG)? A) Cytotrophoblast B) Syncytiotrophoblast C) Extraembryonic mesoderm D) Decidua basalis E) Hypoblast
Answer: B
The syncytiotrophoblast is the outer multinucleated layer of the trophoblast that invades the endometrium and produces hCG. The cytotrophoblast is the inner mononuclear layer that provides progenitor cells. hCG can be detected in maternal serum as early as 8–10 days after conception, peaks at 8–10 weeks, and then declines. It acts to maintain the corpus luteum and its progesterone production.
Q21 [SBA] (Reproductive Physiology) — A patient undergoing controlled ovarian hyperstimulation has an oestradiol level of 3000 pg/mL by cycle day 10. This finding raises concern for the development of ovarian hyperstimulation syndrome. Which of the following physiological mechanisms BEST explains the pathophysiology? A) Oestradiol directly increases capillary permeability at high concentrations B) hCG triggers excessive VEGF release from the hyperstimulated ovaries C) FSH causes massive luteinisation of granulosa cells and ascites formation D) Progesterone induces a systemic inflammatory response-mediated capillary leak E) Inhibin A suppresses antidiuretic hormone leading to fluid shift
Answer: B
In ovarian hyperstimulation syndrome, the exogenous or endogenous hCG surge triggers excessive release of vascular endothelial growth factor (VEGF) from the hyperstimulated granulosa and luteinised cells. VEGF increases capillary permeability, leading to third-space fluid shift (ascites, pleural effusion). Oestradiol levels are a marker of the number of follicles but are not directly causative of the capillary leak.
Q22 [MBA] (Reproductive Physiology) — Which of the following statements regarding the luteal phase of the menstrual cycle are CORRECT? A) The corpus luteum secretes both progesterone and oestradiol B) Luteinising hormone (LH) is essential for corpus luteum maintenance beyond day 8 post-ovulation in a non-conception cycle C) The lifespan of the corpus luteum is approximately 14 days in the absence of hCG D) Relaxin is secreted by the corpus luteum E) Progesterone from the corpus luteum inhibits GnRH pulse frequency via opioidergic pathways
Answer: A, C, D, E
The corpus luteum secretes progesterone and oestradiol. Relaxin is also produced by the corpus luteum. Without hCG (from the implanting embryo), the corpus luteum undergoes luteolysis at approximately 14 days. Progesterone from the corpus luteum acts via opioidergic pathways to slow GnRH pulse frequency, contributing to the negative feedback that prevents new follicular recruitment. LH is only required for the initial formation and early function of the corpus luteum, not for its maintenance after day 8 — that depends on basal LH but withdrawal is not the trigger for luteolysis.
Q23 [SBA] (Reproductive Physiology) — Decidualisation of the endometrium in preparation for implantation is PRIMARILY driven by: A) Oestradiol from the dominant follicle B) Progesterone from the corpus luteum C) hCG from the syncytiotrophoblast D) Prostaglandins from the endometrium E) Leptin from adipose tissue
Answer: B
Decidualisation — the transformation of endometrial stromal cells into large, polygonal decidual cells rich in glycogen and lipids — is primarily driven by progesterone from the corpus luteum. While oestradiol primes the endometrium by stimulating proliferation and upregulating progesterone receptors, the actual secretory transformation and decidualisation require progesterone. hCG from the embryo amplifies this process but is not the primary driver.
Q24 [SBA] (Reproductive Physiology) — A 30-year-old woman at 32 weeks' gestation has a haemoglobin level of 10.2 g/dL (non-pregnant reference: 12–15 g/dL). Which of the following BEST explains the physiological basis for this drop in haemoglobin concentration? A) Impaired erythropoiesis due to relative iron deficiency in pregnancy B) Haemodilution from a disproportionate increase in plasma volume relative to red cell mass C) Increased haemolysis of senescent red blood cells due to altered splenic function D) Reduced erythropoietin production due to increased renal plasma flow E) Fetal iron sequestration resulting in maternal iron-deficiency anaemia
Answer: B
In pregnancy, plasma volume increases by approximately 50% (from 2.5 L to 4 L), while red cell mass increases by only 25%. This disproportionate expansion leads to a physiological haemodilution (so-called "physiological anaemia of pregnancy"), with haemoglobin typically falling to 10–11 g/dL in the second and third trimesters. Erythropoietin levels actually increase in pregnancy. True iron-deficiency anaemia must be distinguished from this physiological change.
Q25 [MBA] (Reproductive Physiology) — Which of the following substances are SYNTHESISED by the syncytiotrophoblast? A) Human chorionic gonadotropin (hCG) B) Human placental lactogen (hPL) C) Progesterone D) Oestriol E) Alpha-fetoprotein (AFP)
Answer: A, B, C, D
The syncytiotrophoblast synthesises hCG, hPL, progesterone, and oestrogens (including oestriol, oestrone, and oestradiol). The fetus provides precursors (e.g., dehydroepiandrosterone sulphate from the fetal adrenal for oestriol synthesis via the placental aromatase pathway, the "feto-placental unit"). Alpha-fetoprotein is produced by the fetal yolk sac and fetal liver, not by the placenta.
Q26 [SBA] (Reproductive Physiology) — Fertilisation of the human oocyte typically occurs in which part of the fallopian tube? A) Fimbriae B) Infundibulum C) Ampulla D) Isthmus E) Intramural (interstitial) portion
Answer: C
Fertilisation most commonly occurs in the ampulla of the fallopian tube. The ampulla provides the optimal environment for sperm capacitation, the acrosome reaction, and fusion with the oocyte. The fimbriae capture the oocyte at ovulation, the infundibulum is the funnel-shaped opening, the isthmus is the narrow segment adjacent to the uterus, and the intramural portion traverses the uterine wall.
Q27 [SBA] (Reproductive Physiology) — During the first 8–10 weeks of human pregnancy, the corpus luteum is essential for maintaining the pregnancy because it is the primary source of: A) hCG B) Oestradiol C) Progesterone D) Relaxin E) Inhibin A
Answer: C
Progesterone from the corpus luteum is essential to maintain the endometrial decidua and uterine quiescence during the first 8–10 weeks of pregnancy (the luteoplacental shift). After 8–10 weeks, the placenta takes over as the dominant source of progesterone. hCG is produced by the syncytiotrophoblast, not the corpus luteum. Oestradiol, relaxin, and inhibin A are also produced by the corpus luteum, but progesterone is the critical hormone for pregnancy maintenance.
Q28 [SBA] (Endocrinology) — A 35-year-old woman with hypothyroidism is stabilised on levothyroxine 100 mcg daily and is now 8 weeks pregnant. Her TSH is 4.8 mIU/L (first-trimester target: <2.5 mIU/L). Which of the following BEST explains the increased levothyroxine requirement in pregnancy? A) Increased renal clearance of levothyroxine due to elevated glomerular filtration rate B) Increased thyroxine-binding globulin levels due to oestrogen stimulation C) Placental metabolism of maternal thyroid hormones D) Increased peripheral conversion of T4 to reverse T3 E) hCG-mediated suppression of maternal TSH
Answer: B
In pregnancy, oestrogen stimulates hepatic synthesis of thyroxine-binding globulin (TBG), which increases approximately 2–3 fold. This expands the T4 binding pool, reducing free T4 and T3 concentrations and triggering a compensatory increase in TSH. Women with pre-existing hypothyroidism typically require a 30–50% increase in levothyroxine dose to maintain normal TSH. The increased TBG is the primary driver of altered thyroid function tests in pregnancy.
Q29 [MBA] (Endocrinology) — Which of the following statements about the hypothalamic-pituitary-ovarian (HPO) axis are CORRECT? A) Gonadotropin-releasing hormone (GnRH) is secreted in a pulsatile fashion from the arcuate nucleus of the hypothalamus B) Frequency of GnRH pulses increases in the follicular phase and decreases in the luteal phase C) Continuous (non-pulsatile) GnRH administration suppresses LH and FSH secretion D) Kisspeptin neurons in the hypothalamus directly stimulate GnRH release E) GnRH is released into the portal hypophyseal system as a single daily bolus
Answer: A, B, C, D
GnRH is secreted from the arcuate nucleus in pulses every 60–90 minutes in the follicular phase (faster) and every 2–4 hours in the luteal phase (slower). Pulsatility is essential — continuous GnRH administration causes receptor desensitisation and suppressed gonadotropins (the basis of GnRH agonist therapy). Kisspeptin, acting via the KISS1 receptor (GPR54), is a major regulator of GnRH neuronal activity. GnRH is released in multiple pulses per day, not a single daily bolus.
Q30 [SBA] (Endocrinology) — The conversion of cholesterol to pregnenolone, the rate-limiting step in steroidogenesis, is catalysed by which enzyme? A) 3β-hydroxysteroid dehydrogenase B) 17α-hydroxylase C) Cholesterol side-chain cleavage enzyme (P450scc) D) Aromatase (P450arom) E) 21β-hydroxylase
Answer: C
The cholesterol side-chain cleavage enzyme (CYP11A1, P450scc) located on the inner mitochondrial membrane catalyses the conversion of cholesterol (27 carbons) to pregnenolone (21 carbons). This is the rate-limiting and hormonally regulated step of steroidogenesis under the control of trophic hormones (ACTH, LH). 3β-HSD converts pregnenolone to progesterone, 17α-hydroxylase is involved in androgen production, aromatase converts androgens to oestrogens, and 21β-hydroxylase converts progesterone to deoxycorticosterone.
Q31 [SBA] (Endocrinology) — A 28-year-old woman presents with secondary amenorrhoea, galactorrhoea, and a serum prolactin of 180 ng/mL (normal <25). Which of the following is the MOST likely explanation for hyperprolactinaemia-induced anovulation? A) Direct inhibition of ovarian steroidogenesis by prolactin B) Suppression of GnRH pulse frequency by prolactin-mediated increase in hypothalamic dopamine C) Inhibition of GnRH secretion via increased hypothalamic opioidergic tone D) Downregulation of FSH receptors on granulosa cells E) Increased peripheral conversion of androgens to oestrogens
Answer: C
Hyperprolactinaemia suppresses GnRH pulse frequency through increased hypothalamic opioidergic (β-endorphin) and possibly dopaminergic pathways, leading to reduced LH pulse frequency, impaired folliculogenesis, and anovulation. Prolactin does not directly inhibit ovarian steroidogenesis to a significant degree. While prolactin is regulated by dopamine (tonic inhibition), the mechanism by which high prolactin impairs GnRH is primarily via opioidergic rather than dopaminergic pathways.
Q32 [MBA] (Endocrinology) — Which of the following changes in glucose metabolism are NORMAL physiological adaptations to pregnancy? A) Fasting blood glucose levels are lower than in the non-pregnant state B) Postprandial glucose levels are higher and return to baseline more slowly C) Insulin secretion increases progressively throughout pregnancy D) Insulin sensitivity increases in the second trimester E) Hepatic glucose production decreases in late pregnancy
Answer: A, B, C
In normal pregnancy, fasting glucose falls due to increased fetal glucose consumption and expanded plasma volume. Postprandial glucose rises higher and takes longer to normalise because of pregnancy-induced insulin resistance (primarily driven by hPL, progesterone, and cortisol from mid-pregnancy onward). Insulin secretion increases progressively to compensate. Insulin sensitivity actually decreases in the second and third trimesters (not increases). Hepatic glucose production increases in late pregnancy to meet maternal and fetal demands.
Q33 [SBA] (Endocrinology) — A 32-year-old woman at 36 weeks' gestation is diagnosed with gestational diabetes mellitus. She is started on metformin. Which of the following BEST describes the primary mechanism of action of metformin in improving glycaemic control? A) Stimulation of pancreatic β-cell insulin secretion B) Inhibition of hepatic gluconeogenesis and increased peripheral insulin sensitivity C) Slowing of intestinal carbohydrate absorption D) Inhibition of renal glucose reabsorption E) Activation of peroxisome proliferator-activated receptor gamma (PPARγ)
Answer: B
Metformin primarily acts by activating AMP-kinase in the liver, suppressing hepatic gluconeogenesis, and increasing peripheral insulin sensitivity in muscle and adipose tissue. It does NOT stimulate insulin secretion (unlike sulfonylureas) — this is why it rarely causes hypoglycaemia. It does not act via PPARγ (that is the mechanism of thiazolidinediones) or primarily via reduced intestinal absorption. SGLT2 inhibitors block renal glucose reabsorption.
Q34 [SBA] (Endocrinology) — A female fetus is exposed to high levels of androgens in utero due to congenital adrenal hyperplasia (21-hydroxylase deficiency). This results in virilisation of the external genitalia. Which of the following structures is most likely affected? A) Ovaries B) Uterus C) Upper vagina D) Urogenital sinus derivatives E) Wolffian ducts
Answer: D
In 46,XX congenital adrenal hyperplasia, excess androgens from the fetal adrenal cause virilisation of the urogenital sinus (which forms the lower vagina, urethra, and vestibular structures) and the genital tubercle (clitoral enlargement). The ovaries, uterus, and upper vagina (müllerian structures) are not affected because anti-müllerian hormone is not present. Wolffian (mesonephric) duct regression is normal in the absence of testis-derived AMH and testosterone.
Q35 [MBA] (Endocrinology) — Which of the following steroidogenic enzymes are expressed in the human placenta? A) Aromatase (CYP19A1) B) 17α-hydroxylase/17,20-lyase (CYP17A1) C) 3β-hydroxysteroid dehydrogenase (3β-HSD) D) Cholesterol side-chain cleavage enzyme (CYP11A1, P450scc) E) 21β-hydroxylase (CYP21A2)
Answer: A, C, D
The placenta expresses aromatase (converts fetal androgens to oestrogens), 3β-HSD (converts pregnenolone to progesterone), and P450scc (converts cholesterol to pregnenolone). Critically, the placenta LACKS CYP17A1 (17α-hydroxylase/17,20-lyase), meaning it cannot convert progesterone to androgens — this is why the placenta depends on fetal adrenal C19 steroids (DHEA-S) as precursors for oestrogen synthesis. The placenta also lacks 21β-hydroxylase.
Q36 [SBA] (Endocrinology) — A 48-year-old woman is undergoing in vitro fertilisation. On the day of trigger, her serum progesterone level is 2.1 ng/mL (>1.5 ng/mL is considered elevated). Which of the following is the MOST likely consequence of this elevated progesterone before hCG administration? A) Improved endometrial receptivity and implantation rates B) Premature luteinisation disrupting endometrium-embryo synchrony C) Increased oocyte maturation with higher fertilisation rates D) Reduced risk of ovarian hyperstimulation syndrome E) No significant impact on cycle outcomes
Answer: B
Elevated progesterone (>1.5 ng/mL) on the day of hCG trigger in controlled ovarian hyperstimulation is associated with premature luteinisation of the endometrium, advancing the endometrial window of implantation and creating asynchrony with the developing embryo. This results in reduced implantation and pregnancy rates. It is a well-recognised phenomenon in IVF, particularly in high-responder patients.
Q37 [SBA] (Endocrinology) — A 26-year-old woman with polycystic ovary syndrome (PCOS) presents with hirsutism and oligomenorrhoea. Laboratory findings show LH:FSH ratio 3:1, total testosterone 3.0 nmol/L (normal <1.8), and SHBG 20 nmol/L (normal 40–120). Which of the following BEST explains the elevated free androgen index in PCOS? A) Increased adrenal androgen production B) Reduced hepatic SHBG synthesis due to relative oestrogen deficiency C) LH-driven theca cell hyperandrogenism combined with low SHBG from hyperinsulinaemia D) Increased peripheral 5α-reductase activity E) Decreased androgen clearance from hepatic steatosis
Answer: C
In PCOS, elevated LH drives theca cell androgen production (theca cells express LH receptors and respond with increased CYP17A1 activity). Concurrent hyperinsulinaemia (common in PCOS) suppresses hepatic SHBG synthesis, increasing the free (bioavailable) androgen fraction. While increased 5α-reductase activity contributes to hirsutism, the elevated free androgen index is primarily driven by the combination of hyperandrogenism and low SHBG.
Q38 [SBA] (Fetal & Neonatal Physiology) — At birth, which of the following events is the PRIMARY stimulus for the first breath in a healthy term neonate? A) Cord clamping causing increased systemic vascular resistance B) Cold exposure activating brown adipose tissue thermogenesis C) Hypoxia, hypercapnia, and acidosis after placental separation D) Surfactant secretion from type II pneumocytes triggered by catecholamines E) Reversal of the ductus venosus shunt
Answer: C
The primary stimulus for the first breath is the combined effect of hypoxia, hypercapnia, and acidosis that develops during and immediately after delivery. These chemical stimuli activate peripheral and central chemoreceptors, triggering the respiratory centre in the medulla. While cold exposure, cord clamping, and catecholamine release contribute to the overall transition, the chemoreceptor drive is the principal trigger for initiating respiration.
Q39 [MBA] (Fetal & Neonatal Physiology) — Which of the following statements about the fetal circulation are CORRECT? A) The ductus venosus shunts oxygenated blood from the umbilical vein directly into the inferior vena cava, bypassing the hepatic sinusoids B) The foramen ovale directs oxygenated blood from the right atrium to the left atrium, bypassing the pulmonary circulation C) The ductus arteriosus connects the pulmonary trunk to the descending aorta D) Approximately 90% of fetal right ventricular output passes through the ductus arteriosus E) Umbilical arteries carry oxygenated blood from the placenta to the fetus
Answer: A, B, C, D
The ductus venosus connects the umbilical vein (oxygenated) to the inferior vena cava, allowing ~50% of umbilical venous blood to bypass the liver. The foramen ovale directs this oxygenated blood from right to left atrium. The ductus arteriosus connects the pulmonary trunk to the descending aorta; approximately 90% of right ventricular output passes through it because of high pulmonary vascular resistance. Umbilical ARTERIES carry deoxygenated blood FROM the fetus TO the placenta; umbilical VEINS carry oxygenated blood TO the fetus.
Q40 [SBA] (Fetal & Neonatal Physiology) — A preterm infant born at 28 weeks' gestation develops respiratory distress syndrome. The underlying pathophysiology is PRIMARILY due to: A) Immaturity of the chest wall muscles and diaphragm B) Deficiency of surfactant resulting in increased alveolar surface tension and atelectasis C) Persistent pulmonary hypertension causing right-to-left shunting D) Inadequate central respiratory drive from the medullary respiratory centre E) Congenital pulmonary airway malformation
Answer: B
Respiratory distress syndrome (RDS) in preterm infants is primarily caused by surfactant deficiency. Surfactant (a mixture of phospholipids, mainly dipalmitoylphosphatidylcholine, and surfactant proteins A-D) reduces alveolar surface tension, preventing collapse at end-expiration. Type II pneumocytes begin producing surfactant at approximately 24 weeks but adequate quantities are not present until 34–36 weeks. Surfactant deficiency leads to diffuse atelectasis, hyaline membrane formation, and ventilation-perfusion mismatch.
Q41 [SBA] (Fetal & Neonatal Physiology) — In the fetal heart, where is the most well-oxygenated blood found? A) Right atrium B) Left atrium C) Right ventricle D) Left ventricle E) Pulmonary trunk
Answer: B
The most well-oxygenated blood in the fetal circulation is found in the left atrium and left ventricle (and subsequently in the ascending aorta, brachiocephalic trunk, and carotid arteries supplying the brain). Oxygenated blood from the umbilical vein passes through the ductus venosus into the inferior vena cava, is preferentially directed across the foramen ovale to the left atrium, and then to the left ventricle and ascending aorta.
Q42 [MBA] (Fetal & Neonatal Physiology) — Which of the following are recognised components of the APGAR scoring system? A) Heart rate B) Respiratory effort C) Muscle tone D) Reflex irritability E) Oxygen saturation by pulse oximetry
Answer: A, B, C, D
The APGAR score comprises five components: Appearance (skin colour), Pulse (heart rate), Grimace (reflex irritability), Activity (muscle tone), and Respiration (respiratory effort). Each is scored 0, 1, or 2, with a maximum total of 10. Oxygen saturation monitoring (pulse oximetry) is a separate tool used in neonatal resuscitation but is not part of the APGAR scoring system.
Q43 [SBA] (Fetal & Neonatal Physiology) — A term neonate at 5 minutes of age has a heart rate of 90 bpm, weak cry, some flexion of extremities, grimaces to suction, and acrocyanosis. What is the APGAR score? A) 4 B) 5 C) 6 D) 7 E) 8
Answer: C
Scoring: Appearance — acrocyanosis (pink body, blue extremities) = 1; Pulse — 90 bpm (<100) = 1; Grimace — grimaces to stimulation = 1; Activity — some flexion = 1; Respiration — weak cry/slow irregular = 1. Total = 6. A normal term infant would score 9–10 (with 2 in each category except Appearance losing 1 point for acrocyanosis).
Q44 [MBA] (Fetal & Neonatal Physiology) — Which of the following cardiovascular changes occur at birth during the transition from fetal to neonatal circulation? A) Closure of the ductus arteriosus occurs functionally within the first 24–48 hours due to smooth muscle contraction in response to increased arterial oxygen tension B) The foramen ovale closes functionally when left atrial pressure exceeds right atrial pressure C) The ductus venosus constricts in response to loss of umbilical venous blood flow D) Pulmonary vascular resistance falls dramatically as the lungs expand with air E) Systemic vascular resistance decreases because of the low-resistance placental circuit
Answer: A, B, C, D
At birth, cord clamping removes the low-resistance placenta, INCREASING systemic vascular resistance. Lung expansion causes pulmonary vascular resistance to fall dramatically, increasing pulmonary blood flow. Left atrial pressure rises (from increased pulmonary venous return) exceeding right atrial pressure, closing the foramen ovale functionally. The ductus arteriosus constricts in response to rising PaO₂. The ductus venosus closes due to reduced umbilical venous return. Systemic vascular resistance INCREASES (not decreases) after cord clamping.
Q45 [SBA] (Fetal & Neonatal Physiology) — The umbilical cord normally contains three vessels. The most common abnormal cord finding in neonates with a single umbilical artery is associated with which of the following? A) Increased risk of twinning B) Increased risk of congenital renal anomalies C) Increased risk of neural tube defects D) Increased risk of cardiac anomalies E) Increased risk of chromosomal trisomy only
Answer: D
A single umbilical artery (two-vessel cord: one artery, one vein) occurs in approximately 1% of pregnancies. It is associated with an increased risk of congenital anomalies, particularly renal and cardiac anomalies. When an isolated finding (no other structural anomaly), the prognosis is generally good, but a detailed fetal anatomical survey is indicated. It is not specifically associated with neural tube defects or twinning.
Q46 [MBA] (Pathology) — Which of the following features are characteristic of COAGULATIVE (coagulation) necrosis? A) Preservation of tissue architecture for several days B) Loss of cell outlines with retention of basic structural framework C) Characteristic "ghost cells" with preserved eosinophilia D) Liquefaction of tissue by proteolytic enzymes from neutrophils E) Most commonly seen in myocardial infarction
Answer: A, C, E
Coagulative necrosis is characterised by preservation of tissue architecture for several days despite cell death. Cells show "ghost outlines" with preserved eosinophilia (loss of nuclei, retained cytoplasmic detail). It is the most common pattern of ischaemic necrosis, classically seen in myocardial infarction (heart) and renal/splenic infarcts. Loss of cell outlines and liquefaction are features of LIQUEFACTIVE necrosis, typically caused by bacterial infections and in the brain.
Q47 [SBA] (Pathology) — A 45-year-old woman undergoes hysterectomy for symptomatic fibroids. Histology reveals a well-circumscribed, whorled white-tan myometrial lesion composed of interlacing fascicles of benign smooth muscle cells. No cytological atypia, no coagulative necrosis, and <4 mitoses per 10 high-power fields (HPF). This lesion is BEST classified as: A) Leiomyosarcoma B) Smooth muscle tumour of uncertain malignant potential (STUMP) C) Cellular leiomyoma D) Atypical leiomyoma E) Leiomyoma with symplastic change
Answer: C
Cellular leiomyomas are benign smooth muscle tumours with increased cellularity compared to surrounding myometrium but without cytological atypia, coagulative necrosis, or significant mitotic activity (<4 mitoses/10 HPF). They are a variant of the typical leiomyoma. Leiomyosarcoma would show significant atypia, >10 mitoses/10 HPF, and/or coagulative tumour cell necrosis. STUMP is diagnosed when atypical features are present but insufficient for a definite malignancy diagnosis.
Q48 [SBA] (Pathology) — A 32-year-old woman undergoes endometrial biopsy for irregular heavy menstrual bleeding. Histology shows proliferative-type endometrium with scattered small glands lined by ciliated cells showing enlarged, irregular, hyperchromatic nuclei with eosinophilic cytoplasmic inclusions. These nuclear features are characteristic of which of the following iatrogenic endometrial changes? A) Arias-Stella reaction B) Endometrial hyperplasia without atypia C) Progestin effect D) Tamoxifen-associated change E) Chronic endometritis
Answer: D
Tamoxifen, a selective oestrogen receptor modulator (SERM), has agonist effects on the endometrium and can cause a spectrum of changes including benign polyps, hyperplasia, and an increased risk of endometrial carcinoma. A characteristic tamoxifen-associated change includes endometrial glands with enlarged, irregular, hyperchromatic nuclei and eosinophilic cytoplasmic inclusions. Arias-Stella reaction (pregnancy-related) shows hypersecretory changes with enlarged, hyperchromatic nuclei but is associated with decidualised stroma.
Q49 [MBA] (Pathology) — Which of the following are features of a HYDATIDIFORM MOLE on histopathological examination? A) Oedematous swelling of chorionic villi with central cistern formation B) Trophoblastic hyperplasia (circumferential and exuberant) C) Absence of fetal blood vessels in the villi D) Villous invasion into the myometrium E) Presence of fetal parts
Answer: A, B, C
Complete hydatidiform mole shows: (1) markedly oedematous, enlarged villi with central cistern formation, (2) circumferential trophoblastic hyperplasia (both cytotrophoblast and syncytiotrophoblast), and (3) absence of fetal blood vessels (and absence of fetal parts). Partial moles show focal villous hydrops, mild trophoblastic hyperplasia, and PRESENT fetal blood vessels/fetal parts. Villous invasion into myometrium (myometrial invasion) is characteristic of invasive mole, not simple hydatidiform mole.
Q50 [SBA] (Pathology) — A 52-year-old woman presents with postmenopausal bleeding. Endometrial biopsy shows a well-differentiated adenocarcinoma with squamous differentiation. The epithelium shows crowded, complex glands with back-to-back arrangement, intraglandular bridging, and nuclear atypia. There is no myometrial invasion. What is the MOST accurate diagnosis? A) Atypical complex hyperplasia B) Endometrial endometrioid adenocarcinoma, grade 1, FIGO stage IA C) Endometrioid adenocarcinoma with squamous differentiation (adenoacanthoma) D) Serous endometrial carcinoma E) Clear cell carcinoma of the endometrium
Answer: C
The presence of squamous differentiation within an endometrioid adenocarcinoma is termed adenoacanthoma (well-differentiated squamous metaplasia) or adenosquamous carcinoma if the squamous component is malignant. The description fits endometrioid adenocarcinoma with squamous differentiation. Atypical complex hyperplasia shows no stromal invasion (no back-to-back gland crowding without intervening stroma). Serous carcinoma shows papillary architecture with marked nuclear atypia (psammoma bodies are common).
Q51 [SBA] (Pathology) — A 28-year-old woman undergoes amniocentesis at 16 weeks. Amniotic fluid alpha-fetoprotein (AFP) levels are significantly elevated. Which of the following is the MOST likely explanation? A) Down syndrome B) Placental abruption C) Open neural tube defect D) Intrauterine growth restriction E) Rhesus isoimmunisation
Answer: C
Elevated amniotic fluid AFP is most commonly associated with open neural tube defects (anencephaly, spina bifida) and open abdominal wall defects (gastroschisis, omphalocele). AFP is the fetal equivalent of albumin, produced by the fetal liver. An open defect allows direct leakage of fetal proteins into the amniotic fluid. AFP is LOW in Down syndrome (used in triple/quadruple screening). The other options are not typically associated with elevated amniotic fluid AFP.
Q52 [MBA] (Pathology) — Which of the following are recognised histological features of acute inflammation? A) Vasodilation of arterioles and venules B) Increased vascular permeability with exudation of fluid C) Predominant neutrophilic infiltration within the first 6–24 hours D) Granulation tissue formation E) Formation of granulomas
Answer: A, B, C
Acute inflammation is characterised by: (1) vasodilation (increased blood flow causing erythema and warmth), (2) increased vascular permeability (exudation of plasma proteins causing oedema), and (3) neutrophil emigration (predominant in the first 6–48 hours). Granulation tissue formation (angiogenesis, fibroblast proliferation) is a feature of the PROLIFERATIVE phase of healing, days 3–14 after injury. Granulomas are a hallmark of CHRONIC granulomatous inflammation (TB, sarcoidosis).
Q53 [SBA] (Pathology) — A 68-year-old woman presents with ascites and an adnexal mass. Peritoneal fluid cytology shows malignant cells with psammoma bodies and papillary fronds with tufted epithelium. Immunohistochemistry is positive for WT1, PAX8, and CK7, and negative for CK20. Which of the following is the MOST likely primary site? A) Colonic adenocarcinoma metastatic to the ovary B) High-grade serous ovarian carcinoma C) Mucinous ovarian carcinoma D) Granulosa cell tumour E) Endometrial endometrioid adenocarcinoma
Answer: B
High-grade serous ovarian carcinoma (HGSOC) is the most common and most lethal ovarian epithelial malignancy. Characteristic features include papillary architecture, psammoma bodies (laminated calcifications), and marked nuclear atypia. The immunoprofile (WT1+, PAX8+, CK7+, CK20−) is classic for serous carcinoma of gynaecological origin (ovary, fallopian tube, or peritoneum). Colonic metastases are CK20+/CK7−. Granulosa cell tumours are sex cord-stromal tumours and are WT1−.
Q54 [SBA] (Pathology) — A 38-year-old woman has a molar pregnancy evacuated at 10 weeks. Eight weeks later, her serum hCG has plateaued at 250 IU/L (falling from a peak of 200,000 IU/L). A transvaginal ultrasound reveals a 2 cm echogenic lesion in the anterior myometrium. The MOST likely diagnosis is: A) Complete hydatidiform mole B) Partial hydatidiform mole C) Invasive mole D) Choriocarcinoma E) Placental site trophoblastic tumour
Answer: C
Invasive mole (chorioadenoma destruens) is characterised by persistent elevation of hCG after molar evacuation with invasion of hydropic villi into the myometrium. It is the most common form of gestational trophoblastic neoplasia following a complete mole. Choriocarcinoma would show no villi (only sheets of malignant trophoblast) and typically presents with very high hCG and early haematogenous metastases. The presence of villi histologically distinguishes invasive mole from choriocarcinoma.
Q55 [MBA] (Pathology) — Which of the following are recognised causes of CELL INJURY? A) Hypoxia due to reduced blood flow (ischaemia) B) Free radical damage (oxidative stress) C) Impaired intracellular calcium homeostasis D) Depletion of intracellular ATP E) Increased mitochondrial membrane potential
Answer: A, B, C, D
Common mechanisms of cell injury include: hypoxia/ischaemia (reduced oxygen delivery), oxidative stress (reactive oxygen species causing lipid peroxidation, DNA damage, and protein denaturation), impaired calcium homeostasis (increased cytosolic Ca²⁺ activates phospholipases, proteases, and endonucleases), and ATP depletion (failure of Na⁺/K⁺-ATPase causing cellular swelling, failure of Ca²⁺ pumps, and activation of apoptotic pathways). Mitochondrial membrane potential is usually DECREASED (depolarised) in cell injury, activating the mitochondrial permeability transition pore.
Q56 [SBA] (Pathology) — A 34-year-old woman undergoes a cone biopsy for CIN 3 on cervical punch biopsy. Histology of the cone specimen shows full-thickness loss of stratification, nuclear atypia, and mitotic figures extending into the upper two-thirds of the epithelium, but no breach of the basement membrane. This is consistent with: A) CIN 1 (LSIL) B) CIN 2 (HSIL) C) CIN 3 (HSIL) D) Microinvasive squamous cell carcinoma (FIGO stage IA1) E) Invasive squamous cell carcinoma
Answer: C
CIN 3 (HSIL) is defined by full-thickness (or near-full-thickness) dysplastic change involving the upper two-thirds to full thickness of the cervical squamous epithelium, with nuclear atypia, loss of polarity, and mitotic figures at all levels. By definition, there is no invasion through the basement membrane. Microinvasive carcinoma (stage IA1) shows invasion ≤3 mm depth and ≤7 mm horizontal spread. Full-thickness dysplasia with any degree of stromal invasion changes the diagnosis to invasive carcinoma.
Q57 [SBA] (Pathology) — A 40-year-old woman has a unilateral salpingo-oophorectomy for a dermoid cyst. The pathologist reports a cyst lined by keratinised squamous epithelium containing hair shafts and sebaceous material, with a solid nodule (Rokitansky's protuberance) containing calcified tooth-like structures. Which germ cell layers are represented in the cyst wall? A) Ectoderm only B) Endoderm only C) Ectoderm and mesoderm D) Ectoderm, mesoderm, and endoderm E) Mesoderm only
Answer: D
Mature cystic teratoma (dermoid cyst) is a benign germ cell tumour containing derivatives of all three germ cell layers: ectoderm (skin, hair, neural tissue), mesoderm (fat, bone, cartilage, teeth), and endoderm (respiratory/gastrointestinal epithelium, thyroid tissue). Rokitansky's protuberance is the solid nodule from which various tissues arise. Despite the name "dermoid", these are truly teratomas with all three layers represented.
Q58 [SBA] (Pharmacology) — A 26-year-old primigravida at 34 weeks' gestation presents with preterm labour. She has a blood pressure of 110/70 mmHg and heart rate 110 bpm. Which of the following tocolytics would be MOST appropriate given her tachycardia? A) Atosiban B) Nifedipine C) Terbutaline D) Indomethacin E) Salbutamol
Answer: A
Atosiban, a competitive oxytocin/vasopressin V1A receptor antagonist, is the preferred tocolytic in patients with maternal tachycardia because it has minimal cardiovascular side effects. Beta-agonists (terbutaline, salbutamol) cause significant maternal tachycardia, palpitations, and hypokalaemia. Nifedipine can cause hypotension and reflex tachycardia. Indomethacin is a non-selective COX inhibitor used for tocolysis but carries risks of oligohydramnios and premature ductus arteriosus closure after 32 weeks.
Q59 [MBA] (Pharmacology) — Which of the following drugs are considered safe (category B or A) for use in breastfeeding women? A) Paracetamol (acetaminophen) B) Ibuprofen C) Warfarin D) Methotrexate E) Metformin
Answer: A, B, C, E
Paracetamol and ibuprofen are safe in breastfeeding (very low levels in breast milk, short half-lives). Warfarin is safe as it is highly protein-bound and does not pass into breast milk in significant amounts. Metformin passes into breast milk in small amounts and is considered compatible with breastfeeding. Methotrexate is contraindicated in breastfeeding because it is excreted into breast milk and can cause immunosuppression and neutropenia in the infant.
Q60 [SBA] (Pharmacology) — A 29-year-old woman at 28 weeks' gestation presents with a blood pressure of 165/105 mmHg and proteinuria 1.5 g/24 h. She is diagnosed with pre-eclampsia. Which of the following antihypertensive agents is contraindicated in pregnancy due to the risk of fetal oligohydramnios and neonatal anuria? A) Labetalol B) Nifedipine C) Methyldopa D) ACE inhibitors (e.g., enalapril) E) Hydralazine
Answer: D
ACE inhibitors and angiotensin receptor blockers (ARBs) are contraindicated in the second and third trimesters of pregnancy because they cause fetal oligohydramnios, renal tubular dysplasia, neonatal anuria, pulmonary hypoplasia, and skull ossification defects. These effects are due to the importance of the renin-angiotensin-aldosterone system for fetal renal development and function. Labetalol, nifedipine, methyldopa, and hydralazine are all used as first-line agents for hypertension in pregnancy.
Q61 [SBA] (Pharmacology) — A 35-year-old woman with severe postpartum haemorrhage is given 5 IU of oxytocin intravenously. Within 30 seconds, she develops hypotension, flushing, and tachycardia. Which of the following BEST explains this adverse effect? A) Direct myocardial depression by oxytocin B) Anaphylactic reaction to synthetic oxytocin C) Oxytocin-induced vasodilation via endothelial nitric oxide release D) Histamine release from mast cells triggered by the preservative E) Volume overload from the rapid infusion
Answer: C
Oxytocin causes direct vascular smooth muscle relaxation (vasodilation) by stimulating endothelial nitric oxide release, leading to hypotension, reflex tachycardia, and facial flushing when given as a rapid intravenous bolus. This is a dose-dependent, predictable pharmacological effect, not an allergic reaction. The vasodilatory effect is transient but can be significant in haemodynamically compromised patients. Slow intravenous infusion or intramuscular administration reduces this effect.
Q62 [MBA] (Pharmacology) — Which of the following antibiotics are generally SAFE to use during pregnancy (FDA category B or equivalent)? A) Penicillins (e.g., amoxicillin) B) Cephalosporins (e.g., cefalexin) C) Tetracyclines (e.g., doxycycline) D) Macrolides (e.g., erythromycin) E) Aminoglycosides (e.g., gentamicin)
Answer: A, B, D
Penicillins and cephalosporins are category B and widely used in pregnancy (safe, extensive safety data). Erythromycin (except the estolate form, which is associated with hepatotoxicity) is considered safe and is category B. Tetracyclines are category D — contraindicated after 18 weeks' gestation due to fetal tooth discolouration and bone growth impairment. Aminoglycosides carry a risk of fetal ototoxicity (category C/D) and are reserved for serious infections when alternatives are not available.
Q63 [SBA] (Pharmacology) — A 30-year-old woman with bipolar disorder on lithium therapy becomes pregnant. Lithium is associated with which specific teratogenic risk when used in the first trimester? A) Neural tube defects B) Ebstein's anomaly (tricuspid valve abnormality and right ventricular hypoplasia) C) Cleft lip and palate D) Fetal hydantoin syndrome E) Fetal alcohol spectrum disorder
Answer: B
Lithium use in the first trimester is associated with Ebstein's anomaly, a congenital heart defect characterised by apical displacement of the tricuspid valve and right ventricular hypoplasia. The absolute risk is approximately 1 in 1000 (0.1%), which is higher than the background population risk. First-trimester exposure should prompt a detailed fetal echocardiogram. Neural tube defects are associated with valproate, and cleft lip/palate with phenytoin.
Q64 [SBA] (Pharmacology) — A 28-year-old woman at 32 weeks' gestation is diagnosed with Chlamydia trachomatis cervicitis. Which of the following is the recommended first-line antibiotic for treatment during pregnancy? A) Doxycycline B) Ofloxacin C) Azithromycin D) Metronidazole E) Amoxicillin
Answer: C
Azithromycin 1 g orally as a single dose is the recommended first-line treatment for Chlamydia trachomatis infection in pregnancy. Doxycycline and ofloxacin are contraindicated (tetracycline and fluoroquinolone classes respectively). Amoxicillin is an alternative but has lower efficacy. Metronidazole is used for bacterial vaginosis and trichomoniasis, not chlamydia. Azithromycin is safe (category B) and effective as single-dose therapy.
Q65 [MBA] (Pharmacology) — Which of the following physiological changes during pregnancy affect the pharmacokinetics of drugs? A) Increased gastric emptying time leading to delayed absorption of oral medications B) Increased volume of distribution due to expanded plasma volume C) Increased renal clearance due to elevated glomerular filtration rate D) Decreased hepatic metabolism due to reduced cytochrome P450 activity throughout pregnancy E) Decreased concentration of albumin increasing the free fraction of highly protein-bound drugs
Answer: A, B, C, E
In pregnancy, gastric emptying is delayed (particularly in labour), potentially delaying absorption. Plasma volume expands by 40–50%, increasing the volume of distribution for many drugs. GFR increases by 50–60%, accelerating renal clearance of drugs excreted unchanged (e.g., lithium, atenolol). Serum albumin decreases, increasing the free (active) fraction of highly protein-bound drugs. Hepatic metabolism shows variable changes — CYP3A4 activity increases, CYP1A2 decreases, so "decreased activity throughout pregnancy" is not uniformly correct.
Q66 [SBA] (Microbiology) — A 34-year-old primigravida at 18 weeks' gestation has serological screening showing positive IgM and IgG antibodies to Toxoplasma gondii, with low avidity IgG. Which of the following BEST describes the clinical significance of these results? A) The patient has pre-existing immunity from previous infection and no further action is needed B) The patient has a recent or acute infection acquired within the past 12–16 weeks, with risk of vertical transmission C) The patient has a reactivation of latent toxoplasmosis during pregnancy D) The results are equivocal and should be repeated in 4 weeks E) The patient likely has ocular toxoplasmosis and requires retinal examination
Answer: B
Positive IgM and IgG with LOW avidity IgG indicates a recent primary infection (within the past 12–16 weeks). IgG avidity testing helps distinguish recent from past infection — low avidity suggests recent primary infection. Primary Toxoplasma infection in pregnancy carries a risk of vertical transmission (fetal toxoplasmosis), which can cause hydrocephalus, intracranial calcifications, and chorioretinitis. High avidity IgG would indicate past infection. Repeat IgM can persist for months, making avidity testing crucial for timing.
Q67 [MBA] (Microbiology) — Which of the following pathogens are recognised causes of sexually transmitted infections that can be transmitted VERTICALLY to the neonate during vaginal delivery? A) Neisseria gonorrhoeae B) Chlamydia trachomatis C) Treponema pallidum D) Herpes simplex virus (HSV-2) E) Trichomonas vaginalis
Answer: A, B, D, E
Neisseria gonorrhoeae and Chlamydia trachomatis can cause neonatal conjunctivitis (ophthalmia neonatorum) and pneumonia (especially chlamydia). HSV-2 can cause neonatal herpes, a devastating systemic infection with high mortality. Trichomonas vaginalis can be transmitted to the neonate but usually causes only mild or asymptomatic infection. Treponema pallidum is transmitted TRANSPLACENTALLY (not during vaginal delivery) causing congenital syphilis at any stage of pregnancy.
Q68 [SBA] (Microbiology) — A 30-year-old woman at 36 weeks' gestation has a positive rectovaginal swab for Group B Streptococcus (GBS, Streptococcus agalactiae). She has no known drug allergies. Which of the following is the recommended intrapartum antibiotic prophylaxis regimen? A) Oral amoxicillin 500 mg three times daily from 36 weeks until delivery B) Intravenous benzylpenicillin 3 g stat, then 1.5 g every 4 hours until delivery C) Intravenous metronidazole 500 mg every 8 hours D) Intravenous gentamicin 5 mg/kg once daily E) Oral clindamycin 300 mg every 6 hours for 7 days
Answer: B
The recommended intrapartum GBS prophylaxis is intravenous benzylpenicillin 3 g loading dose, then 1.5 g every 4 hours until delivery. Oral antibiotics given antenatally do not eradicate GBS colonisation and are not recommended. Metronidazole provides no GBS coverage. In penicillin-allergic patients, cefazolin (if low-risk allergy) or clindamycin/vancomycin (if high-risk allergy) are alternatives, but ONLY after Sensitivity testing for clindamycin.
Q69 [SBA] (Microbiology) — A 42-year-old woman develops fever, foul-smelling lochia, and lower abdominal tenderness 48 hours after an emergency caesarean section. She has a temperature of 39.2°C, heart rate 105 bpm, and leukocytosis of 18 × 10⁹/L. Which of the following is the MOST likely causative pathogen? A) Streptococcus pyogenes (Group A Streptococcus) B) Escherichia coli C) Chlamydia trachomatis D) Gardnerella vaginalis E) Candida albicans
Answer: B
Endometritis following caesarean section is typically polymicrobial, but Escherichia coli (a Gram-negative facultative anaerobe) is one of the most commonly isolated organisms, along with anaerobes such as Bacteroides fragilis, Peptostreptococcus, and Group B Streptococcus. Chlamydia is more commonly associated with late postpartum endometritis (after 48 hours) or subclinical infection. Group A Streptococcus can cause a more fulminant, rapidly progressive infection but is less common.
Q70 [MBA] (Microbiology) — Which of the following microorganisms are correctly paired with their mode of transplacental transmission causing congenital infection (the TORCH group)? A) Toxoplasma gondii — transplacental transmission after primary maternal infection B) Rubella virus — highest risk of congenital rubella syndrome when infection occurs in the first 8–10 weeks C) Cytomegalovirus (CMV) — most common congenital viral infection; primary or recurrent maternal infection can transmit D) Hepatitis B virus — primarily transmitted transplacentally during the first trimester E) Parvovirus B19 — associated with fetal hydrops due to aplastic anaemia
Answer: A, B, C, E
Toxoplasma, Rubella, CMV, and Parvovirus B19 are all TORCH infections capable of transplacental transmission. For Parvovirus B19 (not always included in classic TORCH but commonly tested), infection in pregnancy can cause fetal aplastic crisis, hydrops fetalis, and fetal death due to the virus's tropism for erythroid progenitor cells. Hepatitis B is transmitted PERINATALLY (during delivery through exposure to maternal blood and secretions), not transplacentally. CMV is indeed the most common congenital viral infection.
Q71 [SBA] (Microbiology) — A 28-year-old woman presents with acute pelvic pain, cervical motion tenderness, and purulent cervical discharge. A diagnosis of acute pelvic inflammatory disease (PID) is made. Which of the following is the MOST important next step in management? A) Take high vaginal swab and await culture results before starting antibiotics B) Treat empirically with broad-spectrum antibiotics covering N. gonorrhoeae and C. trachomatis C) Arrange urgent laparoscopy for diagnostic confirmation D) Prescribe metronidazole alone and review in 48 hours E) Refer for emergency hysterectomy
Answer: B
PID is diagnosed clinically and requires EMPIRIC broad-spectrum antibiotic therapy covering Chlamydia trachomatis and Neisseria gonorrhoeae (the most common causative agents), along with anaerobes. Delaying treatment to await culture results increases the risk of sequelae (tubal infertility, ectopic pregnancy, chronic pelvic pain). Recommended regimens include a cephalosporin (ceftriaxone) plus doxycycline plus metronidazole. Laparoscopy is not required for diagnosis if clinical criteria are met.
Q72 [SBA] (Microbiology) — A 26-year-old woman presents with a painless ulcer on the labium majus, which appeared 10 days after a new sexual partner. On examination, there is a single, clean-based ulcer with firm, raised borders and a non-tenth base. Inguinal lymph nodes are enlarged, firm, and non-tender. Which of the following is the MOST likely diagnosis? A) Genital herpes (HSV-2) B) Syphilis (primary chancre) C) Chancroid (Haemophilus ducreyi) D) Lymphogranuloma venereum (LGV) E) Granuloma inguinale (donovanosis)
Answer: B
Primary syphilis (Treponema pallidum) presents with a PAINLESS chancre — a clean-based ulcer with firm, raised borders, and non-tender regional lymphadenopathy (satellite bubo). HSV-2 causes PAINFUL vesiculoulcerative lesions. Chancroid (H. ducreyi) causes painful, ragged ulcers with tender, suppurative inguinal lymphadenopathy. LGV presents with a painless papule/ulcer followed by painful inguinal lymphadenopathy (buboes). Granuloma inguinale causes painless, beefy-red granulomatous ulcers without significant lymphadenopathy.
Q73 [MBA] (Microbiology) — Which of the following organisms are obligate intracellular pathogens? A) Chlamydia trachomatis B) Neisseria gonorrhoeae C) Treponema pallidum D) Rickettsia species E) Mycoplasma genitalium
Answer: A, D
Chlamydia trachomatis and Rickettsia species are obligate intracellular pathogens — they cannot replicate outside living cells because they cannot synthesise ATP and depend on host cell energy metabolism. Chlamydia exists as elementary bodies (infectious, extracellular) and reticulate bodies (replicating, intracellular). Neisseria gonorrhoeae and Treponema pallidum are fastidious but can be cultured on artificial media. Mycoplasma genitalium is the smallest self-replicating organism but can be grown in cell-free media.
Q74 [SBA] (Immunology) — A 28-year-old primigravida is RhD-negative. Her partner is RhD-positive. She has an uneventful pregnancy and delivers a healthy RhD-positive baby at term. Approximately 20 mL of fetal-maternal haemorrhage is detected by the Kleihauer-Betke test. She received routine anti-D prophylaxis at 28 weeks and again within 72 hours of delivery. Which mechanism BEST explains how anti-D immunoglobulin prevents RhD alloimmunisation? A) Neutralisation of fetal RhD antigen by binding to soluble antigen in maternal circulation B) Suppression of maternal B-cell response via FcγRIIB-mediated inhibitory signalling (negative co-stimulation) C) Induction of maternal T-cell tolerance to RhD through regulatory T-cell expansion D) Opsonisation and rapid clearance of RhD-positive fetal red cells before maternal immune activation E) Competitive inhibition of RhD antigen presentation by dendritic cells
Answer: D
Anti-D immunoglobulin works primarily by opsonising RhD-positive fetal red blood cells in the maternal circulation, leading to their rapid clearance by the reticuloendothelial system (spleen and liver). This removes the antigenic stimulus before the maternal immune system can generate memory B cells and produce anti-D antibodies. While some contribution from FcγRIIB-mediated B-cell inhibition may occur, the dominant mechanism is immune clearance of the target cells.
Q75 [MBA] (Immunology) — Which of the following immunological adaptations contribute to the maintenance of the fetal semi-allograft during pregnancy? A) Trophoblast cells lack classical MHC class Ia molecules (HLA-A, HLA-B) on the cell surface B) Trophoblast cells express HLA-C, HLA-E, and HLA-G, which interact with NK cell receptors C) Decidual natural killer (dNK) cells have a regulatory rather than cytotoxic phenotype D) The maternal immune system is globally suppressed during pregnancy with reduced lymphocyte counts E) Regulatory T cells (Tregs) expand in pregnancy and suppress alloreactive responses
Answer: A, B, C, E
The trophoblast avoids classical MHC I expression (HLA-A, HLA-B) to prevent recognition by maternal cytotoxic T cells. It expresses HLA-C, HLA-E, and HLA-G — these interact with decidual NK cell receptors (KIRs) and promote a tolerant uterine environment. Decidual NK cells are predominantly CD56^bright/CD16^neg and produce cytokines (angiogenic factors) rather than cytotoxicity. Tregs expand in pregnancy and suppress alloreactive T-cell responses. The maternal immune system is NOT globally suppressed — it is a local, specific adaptation; lymphocyte counts and function are largely preserved systemically.
Q76 [SBA] (Immunology) — A 32-year-old woman with known systemic lupus erythematosus (SLE) is planning pregnancy. Her anti-Ro/SSA antibody status is positive. Which of the following fetal complications is she at HIGHEST risk of developing? A) Fetal growth restriction B) Congenital heart block (complete atrioventricular block) C) Neural tube defects D) Fetal macrosomia E) Preterm premature rupture of membranes
Answer: B
Maternal anti-Ro/SSA antibodies cross the placenta from approximately 16 weeks' gestation and can bind to fetal cardiac conducting tissue (atrioventricular node), causing inflammation and fibrosis. This can result in congenital complete heart block, which carries significant morbidity and mortality. The risk is approximately 2–5% for anti-Ro-positive women, with a recurrence risk of 15–20% in subsequent pregnancies. Serial fetal echocardiography from 16–24 weeks is recommended for monitoring.
Q77 [MBA] (Immunology) — Which of the following are examples of Type II hypersensitivity reactions mediated by antibodies directed against cell surface or extracellular matrix antigens? A) Haemolytic disease of the fetus and newborn (HDFN) due to RhD incompatibility B) Autoimmune haemolytic anaemia C) Goodpasture's syndrome D) Systemic lupus erythematosus (Class II renal involvement) E) Graves' disease
Answer: A, B, C
Type II hypersensitivity involves IgG/IgM antibodies directed against antigens on cell surfaces or extracellular matrix, leading to opsonisation and phagocytosis (HDFN, autoimmune haemolytic anaemia), complement-mediated lysis, or antibody-dependent cellular cytotoxicity. Goodpasture's syndrome involves anti-glomerular basement membrane antibodies (Type II). SLE is a Type III hypersensitivity (immune complex deposition). Graves' disease is Type V (antibody-mediated receptor stimulation).
Q78 [SBA] (Immunology) — A 34-year-old woman presents with recurrent second-trimester miscarriages (three losses between 14–18 weeks). She is diagnosed with antiphospholipid syndrome (APS) based on positive lupus anticoagulant and moderate titres of IgG anticardiolipin antibodies. Which of the following BEST describes the primary thrombotic mechanism in obstetric APS? A) Antibody-mediated inhibition of protein C and annexin V on the trophoblast surface B) Direct endothelial injury causing platelet aggregation C) Complement-mediated lysis of decidual vessels D) Antibody-induced apoptosis of fetal endothelial cells E) Vasculitis of the spiral arteries
Answer: A
In obstetric APS, antiphospholipid antibodies (aPL) bind to beta-2 glycoprotein I on the trophoblast surface. This disrupts the protective annexin V shield (an anticoagulant protein) and interferes with the protein C pathway, creating a prothrombotic state at the maternal-fetal interface. This leads to placental thrombosis, infarction, and pregnancy loss. While complement activation may contribute, the annexin V displacement and protein C inhibition are the primary described mechanisms.
Q79 [SBA] (Biochemistry) — A 30-year-old woman at 10 weeks' gestation presents with hyperemesis gravidarum. She has been unable to keep food or fluids down for 3 days. Laboratory results show: Na⁺ 135 mmol/L, K⁺ 3.0 mmol/L, Cl⁻ 90 mmol/L, HCO₃⁻ 32 mmol/L, pH 7.50, pCO₂ 42 mmHg. What acid-base disorder is present? A) Metabolic acidosis with respiratory compensation B) Metabolic alkalosis with appropriate respiratory compensation C) Metabolic alkalosis without respiratory compensation D) Respiratory alkalosis with metabolic compensation E) Mixed metabolic alkalosis and metabolic acidosis
Answer: B
Loss of gastric acid (HCl) from persistent vomiting causes a metabolic alkalosis (elevated HCO₃⁻ and pH). The expected respiratory compensation would be hypoventilation to increase pCO₂ (↑pCO₂), but here the pCO₂ is 42 mmHg, which is within the normal range (35–45 mmHg) and NOT elevated as would be expected for full compensation. This indicates that respiratory compensation has not yet fully occurred or the vomiting is acute. The normal pCO₂ in the setting of metabolic alkalosis means compensation is partial/incomplete. However, among the options, metabolic alkalosis with appropriate compensation (which would require pCO₂ >45) — since pCO₂ is 42, this is metabolic alkalosis without full respiratory compensation, but option B says "with appropriate respiratory compensation" — actually, appropriate compensation for metabolic alkalosis would be a pCO₂ of 40 + 0.7 × (HCO₃⁻ - 24) = 40 + 0.7 × 8 = 45.6 mmHg. The actual pCO₂ of 42 is slightly lower than expected, suggesting partial compensation. Let me re-evaluate.
Actually, the Winter's formula for metabolic alkalosis compensation: expected pCO₂ = 0.7 × HCO₃⁻ + 20 (±2) = 0.7 × 32 + 20 = 42.4 (±2). So pCO₂ of 42 is exactly appropriate compensation. So this IS metabolic alkalosis with appropriate respiratory compensation.
Q80 [MBA] (Biochemistry) — Which of the following correctly describe the roles of folate and vitamin B12 in cellular metabolism? A) Folate is required for the synthesis of purines and pyrimidines (DNA synthesis) B) Vitamin B12 is a cofactor for methionine synthase, which converts homocysteine to methionine C) Vitamin B12 deficiency leads to a functional folate deficiency because of the methylfolate trap D) The active form of folate is tetrahydrofolate (THF) E) Folate is stored primarily in erythrocytes
Answer: A, B, C, D
Folate (as tetrahydrofolate, THF) is essential for one-carbon transfer reactions in purine and pyrimidine synthesis. Vitamin B12 is a cofactor for methionine synthase (the remethylation pathway: homocysteine → methionine). In B12 deficiency, the methylfolate trap occurs — 5-methyl-THF cannot be converted back to THF (requires B12-dependent methionine synthase), leading to a functional folate deficiency despite adequate folate intake. THF is the active form. Folate is stored in the liver, not primarily in erythrocytes (though erythrocyte folate reflects long-term status).
Q81 [SBA] (Biochemistry) — Aerobic glycolysis yields 2 ATP molecules per molecule of glucose via substrate-level phosphorylation. However, the complete oxidation of glucose via the Krebs cycle and oxidative phosphorylation yields approximately how many additional ATP molecules per glucose? A) 6 B) 12 C) 28 D) 36 E) 50
Answer: C
Complete oxidation of one molecule of glucose yields approximately 30–32 ATP molecules total (2 from glycolysis + 2 from Krebs cycle (GTP) + ~26–28 from oxidative phosphorylation). The most commonly cited figures are ~30–32 ATP per glucose in eukaryotes, with ~28 coming from oxidative phosphorylation beyond glycolysis. Historical estimates of 36–38 were based on older assumptions that underestimated mitochondrial membrane proton leakage. The question asks "how many ADDITIONAL ATP" — beyond the 2 from glycolysis, so ~28 ATP from the Krebs cycle and oxidative phosphorylation.
Q82 [SBA] (Biochemistry) — A 38-year-old woman with a body mass index of 35 kg/m² undergoes a 75 g oral glucose tolerance test to screen for gestational diabetes at 28 weeks. Her fasting glucose is 5.6 mmol/L, 1-hour glucose is 10.8 mmol/L, and 2-hour glucose is 9.2 mmol/L. According to the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria, SINGLE elevated values are sufficient for diagnosis. Which of the following BEST explains why insulin sensitivity decreases as pregnancy progresses? A) Increased oestrogen levels directly inhibit insulin receptor signalling B) Human placental lactogen (hPL), progesterone, and cortisol induce a state of physiological insulin resistance C) The enlarging uterus compresses the pancreas, impairing insulin secretion D) Increased renal clearance of insulin due to elevated GFR E) Thyroid hormone excess in pregnancy impairs glucose uptake
Answer: B
The physiological insulin resistance of pregnancy (seen from mid-pregnancy onwards) is primarily mediated by placental hormones — human placental lactogen (hPL), progesterone, placental growth hormone, and elevated cortisol — which antagonise insulin action at the post-receptor level. This ensures a continuous supply of glucose to the fetus. In women with limited pancreatic β-cell reserve, this challenge unmasks GDM. Oestrogen actually IMPROVES insulin sensitivity in most tissues.
Q83 [MBA] (Biochemistry) — Which of the following vitamins are correctly paired with their biochemical functions? A) Vitamin A (retinol) — cofactor in the visual cycle; gene expression regulation via retinoic acid receptors B) Vitamin D (cholecalciferol) — maintenance of serum calcium via intestinal absorption and bone mobilisation C) Vitamin K — cofactor for γ-glutamyl carboxylase in the synthesis of clotting factors II, VII, IX, and X D) Vitamin C (ascorbic acid) — cofactor for prolyl hydroxylase in collagen synthesis; antioxidant E) Vitamin E (tocopherol) — cofactor for transketolase in the pentose phosphate pathway
Answer: A, B, C, D
Vitamin A (retinol) is essential for vision (11-cis-retinal in rhodopsin) and gene regulation. Vitamin D regulates calcium and phosphate homeostasis. Vitamin K is a cofactor for γ-glutamyl carboxylation of clotting factors. Vitamin C is a cofactor for prolyl and lysyl hydroxylases (collagen synthesis) and a potent antioxidant. Vitamin E is a lipid-soluble antioxidant but is NOT a cofactor for transketolase — that role belongs to thiamine (vitamin B1) as thiamine pyrophosphate (TPP).
Q84 [SBA] (Genetics) — A 32-year-old woman gives birth to a male infant who, at 6 months of age, is noted to have an unbalanced translocation. Karyotyping reveals 46,XY,der(14)t(14;21)(q10;q10)mat. The mother is a balanced Robertsonian translocation carrier. What is the recurrence risk for Down syndrome in this mother's future pregnancies? A) 1% B) 10–15% C) 25% D) 50% E) 100%
Answer: B
For female carriers of a Robertsonian translocation between chromosomes 14 and 21 — t(14;21) — the risk of having a child with translocation Down syndrome is approximately 10–15% (male carriers: 1–3%). The mother is balanced and has 45 chromosomes (45,XX,der(14;21)(q10;q10)). During meiosis, the segregation patterns produce six possible gamete types, with ~10–15% being unbalanced with the derivative 14 plus the normal 21 (functionally trisomy 21).
Q85 [MBA] (Genetics) — Which of the following conditions show an X-linked recessive inheritance pattern? A) Haemophilia A (Factor VIII deficiency) B) Duchenne muscular dystrophy C) Fragile X syndrome D) Red-green colour blindness E) Rett syndrome
Answer: A, B, D
Haemophilia A (F8 gene), Duchenne muscular dystrophy (DMD gene), and red-green colour blindness (OPN1LW/OPN1MW genes) are all X-linked recessive conditions. Fragile X syndrome is X-linked dominant (due to FMR1 repeat expansion) and shows anticipation. Rett syndrome (MECP2 mutation) is X-linked dominant — it is lethal in males and affects females almost exclusively. XLR conditions typically manifest in males (hemizygous) while females are carriers (although may show mild features due to skewed X-inactivation).
Q86 [SBA] (Genetics) — A couple undergoes combined first-trimester screening for aneuploidy at 12 weeks' gestation. The nuchal translucency (NT) is 4.5 mm (>99th centile for CRL). Maternal serum shows low PAPP-A and free β-hCG within normal limits. The combined risk for trisomy 21 is 1:12. Which of the following is the MOST appropriate next step in management? A) Repeat the NT measurement at 14 weeks B) Offer cell-free fetal DNA (cfDNA) screening C) Offer invasive prenatal diagnosis (chorionic villus sampling or amniocentesis) D) Offer detailed 20-week anomaly scan only E) Reassure the couple that the risk remains low
Answer: C
An NT >3.5 mm (or >99th centile) is a high-risk finding independent of serum biochemistry, carrying an increased risk of aneuploidy (trisomies 21, 18, 13, Turner syndrome) and structural anomalies (congenital heart disease). The combined risk of 1:12 is high risk (>1:150 threshold). The appropriate next step is to offer invasive prenatal diagnosis (CVS at 11–14 weeks or amniocentesis at >15 weeks) for definitive karyotype/microarray. cfDNA is a screening test and would not replace invasive testing given the markedly abnormal NT.
Q87 [SBA] (Genetics) — A 28-year-old woman is found to have a 45,X karyotype on amniocentesis performed for increased nuchal translucency. She is counselled about the likely phenotype. Which of the following features is LEAST likely to be present in a liveborn female with Turner syndrome? A) Webbed neck B) Short stature C) Gonadal dysgenesis and infertility D) Coarctation of the aorta E) Intellectual disability
Answer: E
Turner syndrome (45,X) is characterised by short stature, webbed neck, low hairline, broad chest with widely spaced nipples, gonadal dysgenesis (streak gonads, infertility), and cardiovascular anomalies (coarctation of the aorta, bicuspid aortic valve). Intellectual disability is NOT a typical feature — most girls with Turner syndrome have normal intelligence, though they may have specific learning difficulties (e.g., visuospatial deficits, impaired social cognition).
Q88 [MBA] (Genetics) — Which of the following statements regarding the inheritance of mitochondrial DNA (mtDNA) disorders are CORRECT? A) Mitochondrial disorders are inherited exclusively through the maternal line B) Mitochondrial DNA is present in sperm mitochondria which enter the oocyte at fertilisation C) Heteroplasmy refers to the presence of both wild-type and mutant mtDNA within a cell D) The phenotypic expression of mtDNA mutations depends on the threshold level of mutant mtDNA E) All children of a male with an mtDNA mutation will inherit the mutation
Answer: A, C, D
Mitochondrial disorders show strict maternal inheritance because paternal mitochondria in the sperm are actively degraded after fertilisation (via ubiquitination and autophagy). Heteroplasmy (mixed wild-type and mutant mtDNA) is a key concept — the proportion of mutant mtDNA determines whether a disease manifests. The threshold effect means a certain percentage of mutant mtDNA must be present before disease expression occurs (varies by tissue). Sperm mitochondria DO enter the oocyte but are actively eliminated. Males with mtDNA mutations do NOT pass them to offspring.
Q89 [SBA] (Embryology) — The urogenital sinus is a midline endodermal structure that develops during the 4th–7th week of embryonic development. In the female, which of the following structures is NOT derived from the urogenital sinus? A) Lower one-third of the vagina B) Bartholin's glands (greater vestibular glands) C) Paraurethral glands (Skene's glands) D) Urethra E) Fallopian tubes
Answer: E
The urogenital sinus gives rise to: the urethra (and paraurethral/Skene's glands), the lower one-third of the vagina (the upper two-thirds are derived from the paramesonephric/müllerian ducts), Bartholin's (greater vestibular) glands, and vestibular bulbs. The fallopian tubes are derived from the CEPHALIC portion of the paramesonephric (müllerian) ducts, not from the urogenital sinus.
Q90 [MBA] (Embryology) — Which of the following are recognised as Müllerian (paramesonephric) duct anomalies? A) Unicornuate uterus (with or without a rudimentary horn) B) Uterus didelphys C) Bicornuate uterus D) Septate uterus E) Turner syndrome (45,X)
Answer: A, B, C, D
Müllerian duct anomalies result from failed or incomplete fusion, resorption, or development of the paramesonephric ducts. These include: unicornuate (one duct develops), didelphys (complete failure of fusion, two separate uteri), bicornuate (partial fundal fusion failure, heart-shaped), and septate (complete fusion but failed resorption of the midline septum). Turner syndrome involves gonadal dysgenesis from loss of the second X chromosome (short arm genes essential for ovarian development) and is NOT classified as a Müllerian duct anomaly — the Müllerian ducts develop normally in 45,X fetuses.
Q91 [SBA] (Embryology) — During the 8th week of embryonic development, the descent of the ovaries and testes is guided by a fibromuscular cord that extends from the developing gonad to the labioscrotal swelling. What is this structure called? A) Gubernaculum B) Processus vaginalis C) Round ligament of the uterus D) Proper ligament of the ovary E) Mesonephric duct
Answer: A
The gubernaculum (genitioinguinal ligament) is a fibromuscular cord that connects the inferior pole of the developing gonad to the labioscrotal swellings. In the female, the gubernaculum becomes the round ligament of the uterus (from the uterus to the labia majora) and the proper ligament of the ovary (from the ovary to the uterus). The processus vaginalis is a peritoneal evagination that precedes testicular descent (but obliterates in females).
Q92 [MBA] (Embryology) — Which of the following processes occur during the acrosome reaction of the spermatozoon? A) Fusion of the outer acrosomal membrane with the sperm plasma membrane B) Release of hydrolytic enzymes including hyaluronidase and acrosin C) Exposure of the inner acrosomal membrane D) Sperm penetration through the zona pellucida E) Fusion of the sperm cell membrane with the oocyte cell membrane
Answer: A, B, C, D
The acrosome reaction involves: (1) fusion of the outer acrosomal membrane with the overlying sperm plasma membrane at the tip of the head, (2) release of acrosomal enzymes (hyaluronidase to digest the cumulus matrix, acrosin to digest the zona pellucida), (3) exposure of the inner acrosomal membrane, and (4) penetration of the sperm through the zona pellucida. The actual fusion of the sperm and oocyte cell membranes (gamete fusion) occurs AFTER the acrosome reaction, at the level of the equatorial segment of the sperm head, and is a separate step.
Q93 [SBA] (Statistics & Epidemiology) — A new screening test for gestational diabetes mellitus (GDM) is evaluated in 500 pregnant women. All women undergo the new test and the reference standard (75 g OGTT). Results show the new test has a sensitivity of 85% and specificity of 90%. The prevalence of GDM in the study population is 12%. What is the positive predictive value (PPV) of the new test? A) Approximately 54% B) Approximately 85% C) Approximately 90% D) Approximately 12% E) Approximately 96%
Answer: A
Using a 2×2 table with 500 women and 12% prevalence: 60 have GDM (12% of 500). Sensitivity 85% → 51 true positives (85% of 60). Specificity 90% → 396 true negatives (90% of 440). False positives = 440 − 396 = 44. PPV = TP/(TP + FP) = 51/(51 + 44) = 51/95 ≈ 53.7%.
Q94 [MBA] (Statistics & Epidemiology) — Which of the following study designs are classified as OBSERVATIONAL studies? A) Randomised controlled trial (RCT) B) Cohort study C) Case-control study D) Cross-sectional study E) Crossover trial
Answer: B, C, D
Observational studies include cohort, case-control, and cross-sectional studies — the investigator observes outcomes without intervening. RCTs and crossover trials are INTERVENTIONAL (experimental) designs where the investigator actively assigns the exposure/intervention. Note that the crossover trial is a type of RCT where each participant serves as their own control, switching between treatment and placebo in separate periods.
Q95 [SBA] (Statistics & Epidemiology) — A study investigates the association between maternal serum vitamin D levels in early pregnancy and the risk of preterm birth. The investigators recruit 2000 pregnant women at 12 weeks' gestation, measure serum vitamin D, and follow them to delivery. They compare the proportion of preterm births in women with vitamin D <50 nmol/L versus ≥50 nmol/L. What type of study design is this? A) Case-control study B) Prospective cohort study C) Nested case-control study D) Cross-sectional study E) Randomised controlled trial
Answer: B
This is a prospective (concurrent) cohort study: participants are recruited based on exposure (vitamin D level) and followed forward in time to assess outcome (preterm birth). The key features are: (1) exposure is measured at baseline, (2) participants are followed prospectively, (3) outcome is assessed after follow-up. A case-control study would start with the outcome and look back at exposure. A cross-sectional study measures exposure and outcome simultaneously.
Q96 [SBA] (Statistics & Epidemiology) — In a logistic regression model examining risk factors for pre-eclampsia, the odds ratio for maternal obesity (BMI ≥30 vs BMI 18.5–24.9) is 3.2 with a 95% confidence interval of 1.5–6.8. Which of the following is the CORRECT interpretation of these results? A) Obese women have a 3.2 times higher risk of developing pre-eclampsia compared to normal-weight women B) The odds of pre-eclampsia are 3.2 times higher in obese women compared to normal-weight women, and the result is statistically significant at p <0.05 C) Obese women have a 3.2% absolute increase in pre-eclampsia risk compared to normal-weight women D) The relative risk of pre-eclampsia in obese women is 3.2 E) There is a 95% probability that the true odds ratio lies between 1.5 and 6.8
Answer: B
The odds ratio of 3.2 indicates that the ODDS (not risk) of pre-eclampsia are 3.2 times higher in obese women. Since the 95% confidence interval does not include 1.0 (it ranges from 1.5 to 6.8), the result is statistically significant at p <0.05. Statement A is incorrect because odds ratio is not the same as relative risk (risk ratio). Statement D is incorrect because odds ratio approximates risk ratio only when the outcome is rare — and even then, the statement uses "relative risk" loosely. Statement E is the common misinterpretation of CI — the correct interpretation is that 95% of such intervals will contain the true value.
Q97 [MBA] (Statistics & Epidemiology) — Which of the following are potential sources of BIAS in clinical research? A) Selection bias: systematic differences between the groups being compared B) Recall bias: differential accuracy of remembering past events between cases and controls C) Publication bias: studies with positive results are more likely to be published than those with negative results D) Confounding: a factor associated with both the exposure and the outcome that distorts the true association E) Loss to follow-up in a cohort study that is equally distributed between exposed and unexposed groups
Answer: A, B, C
Selection bias, recall bias, and publication bias are all recognised forms of bias that can distort study results. Confounding is NOT a form of bias — it is a separate concept referring to a mixing of effects where a third factor distorts the exposure-outcome association; it can be addressed by design (randomisation, restriction, matching) or analysis (stratification, multivariate adjustment). Loss to follow-up only introduces bias if it is DIFFERENTIALLY distributed between groups — equal losses do not bias the relative comparison (though they reduce precision).
Q98 [SBA] (Biophysics & Imaging) — In B-mode ultrasound imaging, the resolution along the axis parallel to the ultrasound beam (depth resolution) is PRIMARILY determined by: A) Frequency of the transducer B) Width of the ultrasound beam C) Number of scan lines per frame D) Pulse repetition frequency E) Dynamic range of the receiver
Answer: A
Axial resolution (resolution along the beam axis) is determined by the spatial pulse length, which depends on the frequency and number of cycles per pulse. Higher frequency transducers produce shorter pulses and therefore better axial resolution. Lateral resolution (perpendicular to the beam) is determined by beam width. The number of scan lines affects temporal resolution (frame rate). Pulse repetition frequency determines the maximum imaging depth.
Q99 [MBA] (Biophysics & Imaging) — A cardiotocograph (CTG) trace from a labouring woman at 38 weeks' gestation shows the following features over a 60-minute period: baseline heart rate 155 bpm, variability 6–10 bpm, accelerations present (two accelerations of 20 bpm lasting 30 seconds), and no decelerations. Which of the following statements are CORRECT regarding the interpretation of this CTG? A) The trace is classified as NORMAL (Category I) according to NICHD criteria B) Baseline tachycardia (>160 bpm) is absent C) Moderate variability confirms intact fetal autonomic nervous system function D) The presence of accelerations confirms the absence of fetal acidosis E) The trace has four characteristics meeting normal criteria, all of which are reassuring
Answer: A, B, C, E
This CTG is normal (Category I/NICHD): baseline 110–160 bpm (155 is normal), moderate variability (6–25 bpm is moderate, 6–10 falls within this), accelerations present (≥15 bpm × ≥15 seconds in a term fetus), no decelerations. All four features are reassuring. The presence of accelerations is a strong predictor of the absence of fetal acidosis at the time of monitoring — but statement D says "confirms the absence" which is too absolute; accelerations are highly reassuring but do not guarantee absence of acidosis (the trace must be interpreted in real time). However, in standard teaching, the presence of accelerations with moderate variability is the most reliable indicator of a non-acidotic fetus. Let me reconsider D — in exam context, "confirms" may be considered too strong, but many experts say accelerations essentially rule out acidosis at that moment. I'll include A, B, C, E as the intended answer set.
Q100 [SBA] (Biophysics & Imaging) — A 40-year-old woman who is 8 weeks pregnant undergoes a transvaginal ultrasound because of vaginal bleeding. The scan shows a gestational sac with a mean sac diameter of 30 mm, a yolk sac but no visible fetal pole. Serum hCG is 15,000 IU/L. Which of the following is the MOST appropriate next step? A) Repeat ultrasound in 2 weeks B) Diagnose anembryonic pregnancy (missed miscarriage) and offer medical management C) Diagnose a normal early pregnancy D) Perform a dilation and evacuation immediately E) Check serum progesterone level
Answer: B
*According to NICE and RCOG guidelines, a pregnancy is classified as an anembryonic miscarriage (early pregnancy loss) when a gestational sac with mean diameter ≥25 mm contains no visible fetal pole on transvaginal ultrasound. This gestational sac measures 30 mm with no fetal pole, so the diagnosis of missed miscarriage can be made definitively without the need for a follow-up scan. Definitive criteria for miscarriage diagnosis include: MSD ≥25 mm with no embryo, or CRL ≥7 mm with no fetal heart activity, or absence of embryonic cardiac activity 2 weeks after a scan showing a gestational sac without an embryo.