Endocrinology of Pregnancy Practice Questions

Q: What change occurs in the resistance of the uteroplacental vasculature during pregnancy?

High resistance to low resistance.. ### Explanation The correct answer is **B. High resistance to low resistance.** **1. Why it is correct:** In a non-pregnant state, the uterine arteries are high-resistance vessels. During pregnancy, the demand for blood flow to the fetus increases significantly (from ~50 mL/min to ~600–700 mL/min). To accommodate this, a process called **trophoblastic invasion** occurs. Cytotrophoblasts invade the maternal **spiral arteries**, replacing the muscular and elastic layers with fibrinoid material. This transforms narrow, high-resistance vessels into dilated, tortuous, **low-resistance channels**. This physiological adaptation ensures a continuous, high-volume blood supply to the intervillous space, independent of maternal vasoconstrictive stimuli. **2. Why the other options are wrong:** * **Option A:** Low to high resistance would cause fetal growth restriction and ischemia. This is the pathological state seen in preeclampsia, not normal pregnancy. * **Option C:** If resistance did not change, the uterine blood flow could not increase 10–15 fold, leading to placental insufficiency. * **Option D:** The change is highly predictable and essential for a viable pregnancy; it is a hallmark of normal placentation. **3. High-Yield Clinical Pearls for NEET-PG:** * **Waveform Change:** On Doppler ultrasound, this transition is marked by the **disappearance of the diastolic notch** in the uterine artery by 20–24 weeks. * **Preeclampsia Connection:** Failure of the second wave of trophoblastic invasion (which involves the intramyometrial portion of spiral arteries) leads to persistent high resistance, resulting in **Preeclampsia** and **IUGR**. * **Refractoriness:** During pregnancy, the uteroplacental vasculature becomes refractory to the pressor effects of **Angiotensin II**, further maintaining the low-resistance state.

Q: Which hormone is essential for the salvage of the corpus luteum?

hCG. **Explanation:** The correct answer is **hCG (human Chorionic Gonadotropin)**. **1. Why hCG is correct:** In a normal menstrual cycle, the corpus luteum (CL) has a finite lifespan of about 14 days, after which it degenerates (luteolysis), leading to a drop in progesterone and the onset of menstruation. However, if fertilization occurs, the syncytiotrophoblast of the developing blastocyst begins secreting **hCG**. This hormone is structurally similar to LH (Luteinizing Hormone) and binds to LH receptors on the corpus luteum. This "rescues" or salvages the CL, preventing its regression and stimulating it to continue producing **progesterone**, which is vital for maintaining the decidua and the early pregnancy until the placenta takes over (luteal-placental shift) at around 7–10 weeks. **2. Why the other options are incorrect:** * **FSH (Follicle Stimulating Hormone):** Its primary role is the recruitment and growth of ovarian follicles during the follicular phase; it does not maintain the corpus luteum. * **AFP (Alpha-Fetoprotein):** This is a glycoprotein produced by the fetal yolk sac and liver. It serves as a marker for neural tube defects and chromosomal anomalies but has no endocrine role in maintaining the CL. * **Estrogen:** While produced by the CL and the placenta, estrogen does not "salvage" the CL; rather, its rising levels are a result of a functional CL or placenta. **Clinical Pearls for NEET-PG:** * **Doubling Time:** In early pregnancy, hCG levels double every 48 hours. * **Luteal-Placental Shift:** Occurs between **7–10 weeks**. If the corpus luteum is removed before 7 weeks without progesterone supplementation, miscarriage will occur. * **Structure:** hCG is a glycoprotein with an $\alpha$ and $\beta$ subunit. The **$\beta$ subunit** is unique and used for pregnancy testing.

Q: What is the main source of prolactin in amniotic fluid?

Decidua. **Explanation:** The correct answer is **Decidua**. **1. Why Decidua is the correct answer:** While prolactin is primarily secreted by the anterior pituitary gland in non-pregnant states, during pregnancy, the **decidua** (the modified endometrium) becomes a major extra-pituitary source. Decidual cells synthesize and secrete prolactin into the amniotic fluid via a process regulated by local factors (like IGF-1 and cytokines) rather than dopamine. Prolactin levels in amniotic fluid are significantly higher (up to 10–100 times) than in maternal or fetal plasma, peaking at 15–20 weeks of gestation. Its primary role in the amniotic fluid is **osmoregulation**, preventing fetal dehydration by regulating the transport of water and electrolytes across the chorioamnion. **2. Why the other options are incorrect:** * **Syncytiotrophoblast:** This layer is the primary source of **hCG** (human Chorionic Gonadotropin) and **hPL** (human Placental Lactogen), not prolactin. * **Cytotrophoblast:** These are the stem cells of the placenta that primarily secrete **GnRH** and other releasing hormones. * **Yolk sac of fetus:** The yolk sac is responsible for early hematopoiesis and the production of **Alpha-fetoprotein (AFP)**, but it does not contribute to amniotic prolactin levels. **Clinical Pearls for NEET-PG:** * **Source of Amniotic Prolactin:** Decidua (specifically the decidua capsularis and parietalis). * **Source of Maternal Serum Prolactin:** Maternal Anterior Pituitary. * **Source of Fetal Serum Prolactin:** Fetal Anterior Pituitary. * **Function:** Amniotic prolactin is crucial for maintaining **amniotic fluid volume** and electrolyte balance. * **Bromocriptine Fact:** Dopamine agonists like Bromocriptine inhibit pituitary prolactin but **do not** inhibit decidual prolactin production.

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: Which investigation modality can diagnose gestational diabetes in a primigravida?

Glucose Tolerance Test (GTT). **Explanation:** The **Oral Glucose Tolerance Test (OGTT)** is the gold standard for the **diagnosis** of Gestational Diabetes Mellitus (GDM). In pregnancy, insulin resistance increases due to placental hormones (like hPL). A diagnosis is confirmed when blood glucose levels exceed specific thresholds after a standardized glucose load (usually 75g or 100g), demonstrating the body's inability to maintain euglycemia under stress. **Analysis of Options:** * **HbA1C (Option A):** While useful for monitoring long-term control in pre-existing diabetes, it is **not** used for GDM diagnosis. It lacks sensitivity in pregnancy due to increased red cell turnover and does not reflect acute postprandial glucose spikes common in GDM. * **Fasting Blood Sugar (Option B):** FBS alone is insufficient for diagnosis. Many women with GDM have normal fasting levels but abnormal post-load levels. It is, however, a component of the OGTT. * **Glucose Challenge Test (Option C):** The GCT (50g glucose) is a **screening** tool, not a diagnostic one. A positive GCT (usually >140 mg/dL) indicates the need for a definitive GTT. **NEET-PG High-Yield Pearls:** * **DIPSI Guidelines (India):** A single-step 75g OGTT is recommended. A 2-hour plasma glucose value **≥140 mg/dL** is diagnostic of GDM, regardless of fasting status. * **Timing:** Screening is typically performed between **24–28 weeks** of gestation. * **IADPSG Criteria:** Diagnosis is made if any one value is met: Fasting ≥92 mg/dL, 1-hr ≥180 mg/dL, or 2-hr ≥153 mg/dL. * **First Visit:** High-risk patients should be screened at the first prenatal visit to rule out pre-gestational (overt) diabetes.

Question 1

What change occurs in the resistance of the uteroplacental vasculature during pregnancy?

Accepted Answer

High resistance to low resistance.

Answer

Low resistance to high resistance.

Answer

No change in resistance.

Answer

Resistance varies unpredictably.

Question 2

Which hormone is essential for the salvage of the corpus luteum?

Accepted Answer

hCG

Answer

FSH

Answer

AFP

Answer

Estrogen

Question 3

What is the main source of prolactin in amniotic fluid?

Accepted Answer

Decidua

Answer

Syncytiotrophoblast

Answer

Cytotrophoblast

Answer

Yolk sac of fetus

Question 4

All of the following are true about gestational diabetes except:

Accepted Answer

Approximately one-third of cases progress to permanent diabetes.

Answer

Increased chances of recurrence in subsequent pregnancies.

Answer

Congenital malformations are common complications.

Answer

Insulin is the treatment of choice.

Question 5

Which of the following is true of thyroid nodules during pregnancy?

Accepted Answer

Can be safely removed before 24 weeks gestation.

Answer

Are poorly assessed by fine-needle aspiration.

Answer

When smaller than 0.5 cm, can be reliably detected sonographically.

Answer

If cancerous, confer worse prognosis than if found in non-pregnant controls.

Question 6

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 7

Which of the following are physiological changes of pregnancy?

Accepted Answer

Insulin levels increase and increased Basal Metabolic Rate (BMR)

Answer

Insulin levels increase and hypothyroidism

Answer

Increased Basal Metabolic Rate (BMR) and hypothyroidism

Answer

Growth Hormone (GH) decreases and increased Basal Metabolic Rate (BMR)

Question 8

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 9

Which investigation modality can diagnose gestational diabetes in a primigravida?

Accepted Answer

Glucose Tolerance Test (GTT)

Answer

HbA1C

Answer

Fasting Blood Sugar (FBS)

Answer

Glucose Challenge Test (GCT)

Question 10

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.

Endocrinology of Pregnancy — MCQs

Endocrinology of Pregnancy — MCQs

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