Endocrinology of Pregnancy Practice Questions

Q: Which of the following is the source of HCG in a pregnant female?

Syncytiotrophoblast. **Explanation:** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone essential for maintaining the corpus luteum during early pregnancy. **1. Why Syncytiotrophoblast is correct:** The **syncytiotrophoblast** is the outer, multi-nucleated layer of the trophoblast that invades the uterine wall. It is the functional endocrine unit of the placenta. It synthesizes and secretes not only **hCG** but also Human Placental Lactogen (hPL), estrogen, and progesterone. hCG production begins as early as 6–8 days after fertilization (around the time of implantation). **2. Why the other options are incorrect:** * **Cytotrophoblast:** This is the inner, single-cell layer (the "stem cell" layer) of the trophoblast. While it provides the cells that fuse to form the syncytiotrophoblast, its primary endocrine product is **GnRH**, which locally stimulates the syncytiotrophoblast to produce hCG. * **Langhans layer:** This is simply another name for the **Cytotrophoblast**. In NEET-PG, remember that the Langhans layer tends to thin out after the 20th week of gestation. * **Chorionic villi:** This is a structural term referring to the finger-like projections of the placenta. While the villi contain both cytotrophoblasts and syncytiotrophoblasts, the specific cellular source of the hormone is the syncytiotrophoblast. **Clinical Pearls for NEET-PG:** * **Doubling Time:** In a healthy pregnancy, hCG levels double every **48–72 hours**. * **Peak Levels:** hCG levels reach their peak at **8–10 weeks** (approx. 100,000 mIU/mL) and then decline to a plateau. * **Subunits:** hCG has an $\alpha$ and $\beta$ subunit. The **$\alpha$-subunit** is identical to LH, FSH, and TSH; the **$\beta$-subunit** is unique and is what pregnancy tests detect. * **Thyroid Connection:** High levels of hCG (as seen in molar pregnancies) can cause hyperthyroidism because the $\alpha$-subunit can cross-react with TSH receptors.

Q: What is the diagnosis of imminent ovulation?

LH surge. **Explanation:** The diagnosis of **imminent ovulation** (ovulation about to occur) is best confirmed by detecting the **LH surge**. 1. **Why LH surge is correct:** The LH surge is the most reliable predictor of impending ovulation. Triggered by a peak in estradiol levels (positive feedback), the surge initiates the final maturation of the oocyte and the weakening of the follicular wall. Ovulation typically occurs **24–36 hours after the onset** of the LH surge and **10–12 hours after its peak**. This is the physiological basis for over-the-counter ovulation predictor kits. 2. **Why other options are incorrect:** * **Endometrial biopsy:** This is a retrospective method. It identifies a secretory endometrium, which confirms that ovulation *has already occurred* (due to progesterone influence), rather than predicting it. * **Pain (Mittelschmerz):** While some women experience mid-cycle pelvic pain, it is subjective, inconsistent, and not a definitive diagnostic marker for the exact timing of ovulation. * **Temperature change:** The Basal Body Temperature (BBT) rises by 0.5–1.0°F *after* ovulation has occurred due to the thermogenic effect of progesterone. Like the biopsy, it is a retrospective indicator. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for Ovulation Monitoring:** Serial Transvaginal Ultrasound (TVUS) to track follicular disappearance and the appearance of free fluid in the Pouch of Douglas. * **Best biochemical marker for "Confirmation" of ovulation:** Serum Progesterone levels >3 ng/ml (measured on Day 21 of a 28-day cycle). * **Cervical Mucus:** Under estrogen influence just before ovulation, the mucus becomes thin, watery, and shows **Spinnbarkeit** (high elasticity) and **Ferning** on microscopy.

Q: At which week of gestation is human chorionic gonadotropin (HCG) production maximal?

10-12 weeks. **Explanation:** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone produced by the **syncytiotrophoblast** of the developing placenta. Its primary physiological role is to maintain the corpus luteum, ensuring the continued secretion of progesterone until the placenta takes over steroidogenesis (the luteo-placental shift). **Why 10-12 weeks is correct:** hCG levels become detectable in maternal serum approximately 8–9 days after ovulation (shortly after implantation). The levels rise exponentially, doubling every 48–72 hours. Peak concentration is reached between **10 and 12 weeks of gestation** (specifically around 70–90 days). After this peak, levels decline significantly to a lower plateau which is maintained for the remainder of the pregnancy. **Analysis of Incorrect Options:** * **A (6-8 weeks):** While hCG is rising rapidly during this period, it has not yet reached its physiological zenith. * **B (8-10 weeks):** Some texts suggest the rise begins to slow here, but the absolute peak is generally cited closer to the end of the first trimester (10-12 weeks). * **D (14-16 weeks):** By this stage, the placenta is fully functional (luteo-placental shift is complete), and hCG levels have already begun their decline to a steady state. **High-Yield Clinical Pearls for NEET-PG:** * **Structure:** hCG shares a common **alpha (α) subunit** with LH, FSH, and TSH. Specificity is determined by the **beta (β) subunit**. * **Doubling Time:** In a healthy intrauterine pregnancy, β-hCG levels should increase by at least 66% every 48 hours. * **Abnormal Levels:** * **Higher than expected:** Multiple pregnancy, Molar pregnancy (Hydatidiform mole), or Down Syndrome (Trisomy 21). * **Lower than expected:** Ectopic pregnancy or threatened/spontaneous abortion. * **Nadir:** The lowest level after the peak is reached at approximately 20 weeks.

Q: A girl presents with primary amenorrhea, normal breast development, hirsutism, and acne. What is the most probable diagnosis?

Polycystic Ovarian Disease (PCOD). ### Explanation The clinical presentation of **primary amenorrhea** combined with **normal breast development** and signs of **hyperandrogenism** (hirsutism and acne) is a classic indicator of Polycystic Ovarian Disease (PCOD/PCOS). **1. Why PCOD is the Correct Answer:** In PCOD, the hypothalamic-pituitary-ovarian axis is functional, leading to adequate estrogen production and **normal breast development** (Tanner Stage 5). However, an imbalance in LH/FSH ratios and insulin resistance leads to excess ovarian androgen production. This hyperandrogenism causes **hirsutism and acne**. While PCOD typically presents as secondary amenorrhea, it is a recognized cause of primary amenorrhea in roughly 5-10% of cases where the hormonal imbalance occurs at the onset of puberty. **2. Why Other Options are Incorrect:** * **Klinefelter Syndrome (47, XXY):** This occurs in phenotypic males. They present with small testes, gynecomastia, and infertility, not primary amenorrhea. * **Turner’s Syndrome (45, XO):** These patients typically have **streak ovaries** (estrogen deficiency), resulting in **absent/poor breast development** and short stature. Hyperandrogenism is not a feature. * **Gonadal Dysgenesis:** Similar to Turner’s, there is a failure of ovarian development. Without estrogen, there is no breast development (sexual infantilism). **3. High-Yield Clinical Pearls for NEET-PG:** * **Rotterdam Criteria for PCOS:** Requires 2 out of 3: (1) Oligo/anovulation, (2) Clinical/biochemical hyperandrogenism, (3) Polycystic ovaries on ultrasound. * **LH:FSH Ratio:** Often >2:1 or 3:1 in PCOS. * **Differential for Primary Amenorrhea with Normal Breasts:** Always consider PCOD, Mullerian Agenesis (MRKH), and Androgen Insensitivity Syndrome (AIS). The presence of hirsutism specifically points toward PCOD or Adrenal Hyperplasia.

Q: Fertilization typically takes place how long after ovulation?

1-2 days. **Explanation:** **1. Why Option A is Correct:** Fertilization occurs when a sperm penetrates a mature oocyte. The biological window for this event is strictly governed by the lifespan of the gametes. Following ovulation, the secondary oocyte remains viable and capable of being fertilized for only **12 to 24 hours**. While sperm can survive in the female reproductive tract for 3–5 days, the oocyte's short functional life necessitates that fertilization occurs within **1–2 days** (24–48 hours) of ovulation. This typically takes place in the **ampulla** of the fallopian tube. **2. Why the Other Options are Incorrect:** * **Option B (5-6 days):** By this time, an unfertilized oocyte has already degenerated. However, this timeframe is significant for a different reason: a fertilized embryo (blastocyst) typically reaches the uterine cavity and begins **implantation** 5–7 days after fertilization. * **Option C (8-12 days):** This period corresponds to the completion of implantation and the start of detectable hCG production. * **Option D (>12 days):** This coincides with the expected date of the next menstrual period. If fertilization hasn't occurred within the first 24 hours post-ovulation, the corpus luteum will eventually regress, leading to menstruation. **3. NEET-PG Clinical Pearls:** * **Site of Fertilization:** Ampulla of the fallopian tube (most common site). * **Sperm Capacitation:** Takes roughly 7 hours; must occur in the female reproductive tract before the sperm can fertilize the egg. * **Cortical Reaction:** The mechanism that prevents polyspermy once the first sperm penetrates the oocyte. * **Zygote Transport:** It takes approximately 3–4 days for the zygote to travel through the fallopian tube to the uterus.

Question 1

Which of the following is the source of HCG in a pregnant female?

Accepted Answer

Syncytiotrophoblast

Answer

Cytotrophoblast

Answer

Langhans layer

Answer

Chorionic villi

Question 2

What is the diagnosis of imminent ovulation?

Accepted Answer

LH surge

Answer

Endometrial biopsy

Answer

Pain

Answer

Temperature change

Question 3

Which of the following is NOT true about diabetes in pregnancy?

Accepted Answer

Insulin resistance decreases with pregnancy.

Answer

Glucose challenge test is done between 24-28 weeks.

Answer

50 gm of glucose is given for the screening test.

Answer

Diabetes control before conception is important to prevent malformations.

Question 4

At which week of gestation is human chorionic gonadotropin (HCG) production maximal?

Accepted Answer

10-12 weeks

Answer

6-8 weeks

Answer

8-10 weeks

Answer

14-16 weeks

Question 5

Which of the following hormonal changes are typically observed in Polycystic Ovary Syndrome (PCOS)?
(i) Luteinizing hormone (LH) is elevated
(ii) Total free estrone is decreased
(iii) Insulin is elevated
(iv) Sex hormone-binding globulin (SHBG) is increased
(v) Progesterone is decreased

Accepted Answer

True, False, True, False, True

Answer

False, False, True, True, False

Answer

True, True, True, False, True

Answer

False, True, True, False, True

Question 6

Which of the following is true about human chorionic gonadotropin (hCG)?

Accepted Answer

Prevents involution of the corpus luteum

Answer

Produced by cytotrophoblast

Answer

Reaches maximum levels at 20 weeks of pregnancy

Answer

Secretion starts 2 days after ovulation

Question 7

A 24-year-old woman with chronic hypothyroidism, currently well-controlled on 75 micrograms of thyroxine, wishes to conceive. She does not smoke, drink, or have any other medical ailments. What is the best advice regarding her thyroxine medication during pregnancy?

Accepted Answer

Thyroxine is safe in pregnancy, and the dose will likely need to be increased to avoid hypothyroidism, which can adversely affect the baby.

Answer

Stop taking thyroxine and switch to methimazole.

Answer

Thyroxine is safe during pregnancy but not essential to continue.

Answer

Thyroxine is not safe during pregnancy; it is better for the baby to be hypothyroid than hyperthyroid.

Question 8

A girl presents with primary amenorrhea, normal breast development, hirsutism, and acne. What is the most probable diagnosis?

Accepted Answer

Polycystic Ovarian Disease (PCOD)

Answer

Klinefelter syndrome

Answer

Turner's syndrome

Answer

Gonadal dysgenesis

Question 9

Which of the following statements is FALSE regarding the endocrine changes in a normal pregnancy?

Accepted Answer

TSH rises in the first and second trimesters but falls in the third trimester.

Answer

There is a fall in free T4/T3 levels during the third trimester.

Answer

Thyroid-stimulating hormone (TSH) falls in the first and second trimesters but increases in the third trimester.

Answer

There is an increase in Thyroid Binding Globulin (TBG).

Question 10

Fertilization typically takes place how long after ovulation?

Accepted Answer

1-2 days

Answer

5-6 days

Answer

8-12 days

Answer

More than 12 days

Endocrinology of Pregnancy — MCQs

Endocrinology of Pregnancy — MCQs

On this page

Practice by Chapter

Want unlimited practice?