Maternal-Fetal Medicine Practice Questions

Q: What is the most common association of renal failure in obstetrics?

Pregnancy-induced hypertension (PIH). **Explanation:** Acute Kidney Injury (AKI) in pregnancy is a serious complication, and **Pregnancy-Induced Hypertension (PIH)**, specifically pre-eclampsia and eclampsia, remains the most common cause of renal failure in the obstetric population. **1. Why PIH is the Correct Answer:** The pathophysiology of PIH involves widespread endothelial dysfunction and vasospasm. In the kidneys, this manifests as **Glomerular Endotheliosis** (swelling of endothelial cells and loss of capillary lumen), which leads to a decreased Glomerular Filtration Rate (GFR), proteinuria, and eventually, acute renal failure. While modern management has reduced its incidence, it still accounts for the majority of obstetric AKI cases globally. **2. Analysis of Incorrect Options:** * **Sepsis:** A significant cause of AKI, particularly in the first trimester (due to septic abortion) or postpartum (puerperal sepsis). However, statistically, it follows PIH in overall frequency. * **Abruptio Placentae:** This is the most common cause of **Acute Tubular Necrosis (ATN)** and **Bilateral Renal Cortical Necrosis** in pregnancy due to severe hypovolemia and DIC. While it is a "classic" cause of severe AKI, it is less frequent than PIH. * **HELLP Syndrome:** While HELLP is a severe variant of PIH and frequently involves renal impairment, it is a subset of the broader category of hypertensive disorders of pregnancy. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of AKI in 1st trimester:** Septic abortion. * **Most common cause of AKI in 3rd trimester:** PIH (Pre-eclampsia/Eclampsia). * **Renal Cortical Necrosis:** Classically associated with Abruptio Placentae; it often leads to permanent renal failure. * **Glomerular Endotheliosis:** The pathognomonic renal lesion of pre-eclampsia.

Q: A pregnant woman is found to have excessive accumulation of amniotic fluid. Polyhydramnios is likely to be associated with all of the following conditions, except:

Bilateral renal agenesis. **Explanation:** The volume of amniotic fluid is a dynamic balance between production (primarily fetal urine) and clearance (primarily fetal swallowing). **Polyhydramnios** occurs when there is either excessive production or impaired clearance of fluid. **Why Bilateral Renal Agenesis is the Correct Answer:** In **Bilateral Renal Agenesis** (Potter’s Syndrome), the fetal kidneys fail to develop. Since fetal urine is the primary source of amniotic fluid from the second trimester onwards, its absence leads to **Oligohydramnios** (deficiency of fluid), not polyhydramnios. This is a classic "except" question where the condition leads to the exact opposite pathology. **Analysis of Incorrect Options:** * **Twin Pregnancy:** Polyhydramnios can occur due to increased fetal surface area or, more specifically, in **Twin-to-Twin Transfusion Syndrome (TTTS)**, where the recipient twin develops polyuria and subsequent polyhydramnios. * **Anencephaly:** This neural tube defect causes polyhydramnios via two mechanisms: (1) failure of the fetal swallowing reflex and (2) transudation of fluid from the exposed meninges into the amniotic sac. * **Esophageal Atresia:** This creates a mechanical obstruction in the fetal gastrointestinal tract, preventing the fetus from swallowing and absorbing amniotic fluid, leading to accumulation. **High-Yield Clinical Pearls for NEET-PG:** * **Definition:** Polyhydramnios is defined as an Amniotic Fluid Index (AFI) **> 25 cm** or a Single Deepest Pocket (SDP) **> 8 cm**. * **Maternal Cause:** The most common maternal cause of polyhydramnios is **Maternal Diabetes Mellitus** (due to fetal osmotic diuresis). * **Potter Sequence:** Bilateral renal agenesis → Oligohydramnios → Pulmonary hypoplasia, limb deformities, and flattened facies.

Q: Which of the following is the drug of choice in pregnancy-induced hypertension?

Methyldopa. **Explanation:** **Alpha-methyldopa** is considered the traditional drug of choice for the management of chronic hypertension and pregnancy-induced hypertension (PIH). It is a centrally acting alpha-2 adrenergic agonist that reduces sympathetic outflow. Its preference in pregnancy stems from its long-standing safety profile, lack of teratogenicity, and the fact that it does not compromise uteroplacental blood flow. **Analysis of Options:** * **B. Diltiazem:** This is a calcium channel blocker (CCB). While certain CCBs like Nifedipine are commonly used in pregnancy, Diltiazem is not a first-line agent for PIH due to less clinical data compared to Methyldopa or Labetalol. * **C. Metoprolol:** While beta-blockers can be used, Metoprolol is generally avoided in the first trimester due to risks of fetal bradycardia and potential growth restriction (IUGR). **Labetalol** (a combined alpha/beta-blocker) is the preferred beta-blocker in pregnancy. * **D. Enalapril:** ACE inhibitors and ARBs are **strictly contraindicated** in pregnancy (Category X). They are associated with fetal renal dysgenesis, oligohydramnios, and skull hypoplasia. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (Chronic/Long-term):** Methyldopa. * **Drug of Choice (Acute Hypertensive Crisis/Emergency):** Intravenous **Labetalol** (fastest acting) or Hydralazine. * **Oral Labetalol** is increasingly replacing Methyldopa in modern guidelines due to a faster onset and fewer side effects (like sedation/depression). * **Prophylaxis:** Low-dose Aspirin (75–150 mg) is started before 16 weeks for women at high risk of preeclampsia. * **Magnesium Sulfate ($MgSO_4$):** The drug of choice for seizure prophylaxis and control in Eclampsia.

Q: On TVS, which of the following shapes of the cervix indicates preterm labor?

U shape. **Explanation:** The assessment of cervical morphology via Transvaginal Sonography (TVS) is a critical predictor of preterm labor. The process of cervical effacement occurs through a predictable sequence of structural changes known by the mnemonic **"TRUST"** (T → Y → V → U). 1. **Correct Answer (C):** The **U shape** represents the final stage of cervical funneling. In this stage, the internal os has opened significantly, and the cervical canal has shortened drastically, leaving only a small portion of the distal cervix closed. This indicates advanced cervical ripening and carries the highest risk for imminent preterm delivery. 2. **Incorrect Options:** * **T shape (A):** This is the normal appearance of a closed, long cervix. The internal os is flat, indicating no funneling and a low risk of preterm labor. * **Y shape (B):** This represents the earliest stage of funneling, where the internal os begins to open slightly while the rest of the canal remains closed. * **V shape:** (Though not an option, it follows 'Y') This indicates deeper funneling toward the external os. * **O shape (D):** This is not a standard sonographic term used to describe the progression of cervical funneling in the context of preterm labor. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** TVS is superior to transabdominal ultrasound for measuring cervical length. * **Critical Cut-off:** A cervical length of ** 5 mm. * **Management:** If a short cervix is detected early, interventions include vaginal progesterone or cervical cerclage (e.g., McDonald or Shirodkar technique).

Q: Which of the following is not a predisposing factor for Preeclampsia?

Smoking. **Explanation:** Preeclampsia is a multisystem disorder characterized by new-onset hypertension and proteinuria after 20 weeks of gestation. Understanding its risk factors is crucial for NEET-PG. **Why Smoking is the Correct Answer:** Counter-intuitively, **smoking is a protective factor** against preeclampsia (reducing risk by approximately 30-50%). The underlying medical concept involves the stimulation of placental growth factor (PlGF) and the inhibition of soluble fms-like tyrosine kinase-1 (sFlt-1) by carbon monoxide and nicotine. This helps maintain a pro-angiogenic balance, preventing the endothelial dysfunction typical of preeclampsia. **Analysis of Incorrect Options:** * **Anti-phospholipid antibody (APLA):** This is a major risk factor. APLA syndrome causes placental thrombosis and impaired trophoblastic invasion, leading to placental ischemia and early-onset preeclampsia. * **Gestational Diabetes (GDM):** Hyperinsulinemia and insulin resistance are associated with systemic inflammation and endothelial damage, significantly increasing the risk of hypertensive disorders. * **Molar Pregnancy:** This is a classic "high-yield" risk factor. The excessive trophoblastic proliferation leads to the release of anti-angiogenic factors. Notably, preeclampsia occurring **before 20 weeks** should always raise suspicion of a hydatidiform mole. **Clinical Pearls for NEET-PG:** * **Highest Risk Factor:** A prior history of preeclampsia is the strongest predictor. * **Nulliparity:** Often called the "disease of theories," it is most common in first pregnancies. * **Protective Factors:** Smoking and previous term delivery with a different partner (though the latter is debated). * **Prophylaxis:** Low-dose Aspirin (75–150 mg) started before 16 weeks is recommended for high-risk patients.

Q: What is the typical volume of amniotic fluid at 38 weeks of gestation in a normal pregnancy?

800 cc. **Explanation:** The volume of amniotic fluid is a dynamic indicator of fetal well-being and follows a characteristic pattern of increase and decrease throughout pregnancy. **1. Why 800 cc is correct:** Amniotic fluid volume increases progressively from the first trimester. It reaches its peak volume of approximately **800–1000 mL at 36–38 weeks** of gestation. After 38 weeks, the volume begins to decline physiologically. By 40 weeks (term), it reduces to about 600–800 mL, and if the pregnancy continues to 42 weeks (post-term), it may drop significantly to around 200–400 mL. **2. Analysis of incorrect options:** * **B (1100 cc):** This is slightly above the normal peak range. While individual variations exist, 800 cc is the standard textbook value for 38 weeks. * **C & D (1500 cc and 1800 cc):** These values are pathologically high. A volume exceeding 1500–2000 mL (or an Amniotic Fluid Index > 25 cm) is defined as **Polyhydramnios**, which can be associated with maternal diabetes or fetal anomalies like esophageal atresia. **High-Yield Clinical Pearls for NEET-PG:** * **Source:** Early pregnancy fluid is an ultrafiltrate of maternal plasma; after 20 weeks, **fetal urine** becomes the primary contributor. * **Measurement:** Clinically assessed via USG using the **Amniotic Fluid Index (AFI)**. Normal AFI is 5–24 cm. * **Oligohydramnios:** Defined as a volume < 200 mL at term or an AFI < 5 cm. Often associated with renal agenesis (Potter sequence) or placental insufficiency. * **Specific Gravity:** Approximately 1.008–1.010; it becomes more hypotonic as the fetus nears term due to increased fetal dilute urine.

Question 1

In multiple pregnancy, fetal reduction is typically performed using which of the following agents?

Accepted Answer

Potassium chloride (KCl)

Answer

Mifepristone

Answer

Prostaglandin F2-alpha (PGF2-alpha)

Answer

Methotrexate

Question 2

What is the most common association of renal failure in obstetrics?

Accepted Answer

Pregnancy-induced hypertension (PIH)

Answer

Sepsis

Answer

Abruptio placentae

Answer

HELLP syndrome

Question 3

A pregnant woman is found to have excessive accumulation of amniotic fluid. Polyhydramnios is likely to be associated with all of the following conditions, except:

Accepted Answer

Bilateral renal agenesis

Answer

Twin pregnancy

Answer

Anencephaly

Answer

Esophageal atresia

Question 4

Which of the following is the drug of choice in pregnancy-induced hypertension?

Accepted Answer

Methyldopa

Answer

Diltiazem

Answer

Metoprolol

Answer

Enalapril

Question 5

On TVS, which of the following shapes of the cervix indicates preterm labor?

Accepted Answer

U shape

Answer

T shape

Answer

Y shape

Answer

O shape

Question 6

Which of the following is not a predisposing factor for Preeclampsia?

Accepted Answer

Smoking

Answer

Anti-phospholipid antibody

Answer

Gestational diabetes

Answer

Molar pregnancy

Question 7

A 38-year-old pregnant woman presents with severe vaginal bleeding. Ultrasound confirms placenta previa. What is the characteristic site of implantation in placenta previa?

Accepted Answer

Lower part of the uterine body, overlapping the internal cervical os

Answer

Uterine (fallopian) tubes

Answer

Cervix

Answer

Mesentery of the abdominal wall

Question 8

What is the typical volume of amniotic fluid at 38 weeks of gestation in a normal pregnancy?

Accepted Answer

800 cc

Answer

1100 cc

Answer

1500 cc

Answer

1800 cc

Question 9

Which of the following statements is true regarding umbilical artery Doppler?

Accepted Answer

Absence of end-diastolic flow is normal at term.

Answer

Changes in the flow velocity waveforms of the umbilical artery may be important in the management of high-risk pregnancies.

Answer

Maternal smoking decreases the S/D ratio.

Answer

Increased diastolic flow indicates a worse prognosis.

Question 10

All of the following are true with regards to fetal lung maturity except?

Accepted Answer

L:S ratio is the single best indicator of pulmonary maturity.

Answer

Phosphatidyl choline is the most important part of surfactant.

Answer

More than 50% cells are orange in colour on Nile blue sulphate test.

Answer

Phosphatidyl glycerol in amniotic fluid is 100% confirmatory of lung maturity.

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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