Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine Indian Medical PG Practice Questions and MCQs

Question 111: Which vitamin deficiency is most commonly seen in a pregnant mother undergoing phenytoin therapy for epilepsy?

A. Vitamin B6
B. Vitamin B12
C. Vitamin A
D. Folic acid (Correct Answer)

Explanation: **Explanation:** **Why Folic Acid is the Correct Answer:** Phenytoin is a well-known inducer of the hepatic cytochrome P450 enzyme system, but its primary impact on folate levels is through the inhibition of the enzyme **intestinal folyl polyglutamate hydrolase**. This prevents the breakdown of dietary polyglutamates into monoglutamates, thereby inhibiting absorption. Additionally, phenytoin increases the hepatic metabolism of folate. Chronic phenytoin therapy leads to **Folic acid deficiency** in up to 50% of patients, which can manifest as megaloblastic anemia. In pregnancy, this deficiency is particularly critical as it significantly increases the risk of **Neural Tube Defects (NTDs)**. **Analysis of Incorrect Options:** * **Vitamin B6 (Pyridoxine):** Deficiency is more commonly associated with **Isoniazid (INH)** therapy (used in TB), which inhibits the conversion of B6 to its active form, leading to peripheral neuropathy. * **Vitamin B12 (Cobalamin):** While B12 deficiency also causes megaloblastic anemia, it is typically associated with pernicious anemia, terminal ileal resection, or long-term **Metformin** use, rather than phenytoin. * **Vitamin A:** Deficiency is associated with fat malabsorption syndromes or malnutrition, leading to night blindness. Phenytoin does not interfere with Vitamin A metabolism. **High-Yield Clinical Pearls for NEET-PG:** * **Supplementation:** Pregnant women on phenytoin should receive high-dose Folic acid (**4 mg/day** or 5 mg/day) starting pre-conceptionally to reduce the risk of NTDs. * **Vitamin K:** Phenytoin also interferes with Vitamin K metabolism. To prevent **Hemorrhagic Disease of the Newborn**, Vitamin K (10 mg) should be given to the mother in the last month of pregnancy and to the neonate at birth. * **Fetal Hydantoin Syndrome:** Characterized by craniofacial dysmorphism, hypoplastic nails/phalanges, and growth retardation.

Question 112: Which of the following side-effects is NOT associated with the use of magnesium sulfate in pregnancy?

A. Muscular paralysis
B. Bradycardia (Correct Answer)
C. Cardiac arrhythmias
D. Respiratory depression

Explanation: **Explanation:** Magnesium sulfate ($MgSO_4$) is the drug of choice for seizure prophylaxis in pre-eclampsia and management of eclampsia. It acts as a CNS depressant and a calcium antagonist at the neuromuscular junction. **Why Bradycardia is the correct answer:** While $MgSO_4$ has significant cardiovascular effects at toxic levels, it typically causes **tachycardia** (due to peripheral vasodilation and compensatory mechanisms) or hypotension. Bradycardia is not a characteristic side effect; instead, toxicity leads to **cardiac arrest** in asystole at very high serum concentrations (>25–30 mEq/L). **Analysis of incorrect options:** * **Muscular paralysis:** Magnesium inhibits the release of acetylcholine at the motor endplate. Toxicity manifests as a loss of deep tendon reflexes (7–10 mEq/L), progressing to generalized muscle paralysis. * **Cardiac arrhythmias:** At toxic levels (above 15 mEq/L), magnesium causes conduction delays, leading to EKG changes (prolonged PR/QRS intervals) and potentially fatal arrhythmias. * **Respiratory depression:** This is a critical sign of toxicity (12–15 mEq/L) occurring due to the paralysis of respiratory muscles. **High-Yield NEET-PG Pearls:** 1. **Therapeutic Range:** 4–7 mEq/L. 2. **Sequence of Toxicity:** Loss of Patellar Reflex (earliest sign) → Respiratory Depression → Cardiac Arrest. 3. **Monitoring:** Always check urine output (>30 ml/hr), respiratory rate (>12/min), and patellar reflexes before each dose. 4. **Antidote:** 10 ml of 10% **Calcium Gluconate** IV (administered over 10 minutes).

Question 113: A sinusoidal heart rate pattern is most commonly associated with which of the following conditions?

A. Placenta previa
B. Vasa previa (Correct Answer)
C. Battledore placenta
D. Succenturiate placenta

Explanation: **Explanation:** A **sinusoidal heart rate pattern** is a Category III fetal heart rate (FHR) tracing characterized by a smooth, sine-wave-like undulating pattern with a frequency of 3–5 cycles per minute and an amplitude of 5–15 bpm. It is a classic sign of **severe fetal anemia** or acute fetal hypoxia. **Why Vasa Previa is correct:** In vasa previa, fetal vessels run unprotected by Wharton's jelly across the internal os. When the membranes rupture (ROM), these vessels can lacerate, leading to immediate **fetal exsanguination**. Because the fetus has a small blood volume, rapid blood loss leads to severe anemia and hypoxia, manifesting on the CTG as a sinusoidal pattern. This is a surgical emergency. **Why the other options are incorrect:** * **Placenta Previa:** While it causes significant maternal bleeding, it rarely causes acute fetal blood loss unless there is placental abruption or trauma. The blood lost is primarily maternal. * **Battledore Placenta:** This refers to the insertion of the umbilical cord at the margin of the placenta. It is usually an incidental finding and does not typically cause acute fetal anemia or sinusoidal patterns. * **Succenturiate Placenta:** This is an accessory lobe of the placenta. While it increases the risk of vasa previa (if vessels run between lobes), the condition itself does not cause a sinusoidal pattern unless those vessels rupture. **High-Yield Clinical Pearls for NEET-PG:** * **Apt Test:** Used to differentiate fetal blood from maternal blood in cases of vaginal bleeding (positive in vasa previa). * **Causes of Sinusoidal Pattern:** Fetal anemia (Rh isoimmunization, Parvovirus B19, vasa previa), severe hypoxia, and certain drugs (e.g., narcotics like alphaprodine). * **Management:** A persistent sinusoidal pattern requires immediate Cesarean delivery.

Question 114: Hyperemesis gravidarum is typically most severe at which gestational age?

A. 6 weeks
B. 9 weeks (Correct Answer)
C. 28 weeks
D. 36 weeks

Explanation: **Explanation:** **Hyperemesis Gravidarum (HG)** is a severe form of nausea and vomiting in pregnancy characterized by weight loss, ketonuria, and electrolyte imbalances. The severity and timing of HG are directly correlated with the serum levels of **Human Chorionic Gonadotropin (hCG)**. 1. **Why 9 Weeks is Correct:** Serum hCG levels begin to rise shortly after implantation, doubling every 48–72 hours. These levels reach their **peak between 8 and 12 weeks** of gestation (averaging around 9–10 weeks). Because the pathogenesis of HG is linked to the high concentration of hCG (and its stimulatory effect on the TSH receptor), symptoms are most intense during this peak. 2. **Why Other Options are Incorrect:** * **6 Weeks:** This is typically when "morning sickness" begins (onset), but hCG levels have not yet reached their maximum concentration. * **28 and 36 Weeks:** These represent the third trimester. In most cases, HG resolves by 16–20 weeks as hCG levels plateau and decline. Persistent vomiting in late pregnancy should prompt investigation for other causes like HELLP syndrome, acute fatty liver of pregnancy, or gastrointestinal issues. **High-Yield Clinical Pearls for NEET-PG:** * **Risk Factors:** Multiple gestations and Molar pregnancies (due to excessively high hCG levels). * **Wernicke’s Encephalopathy:** A rare but serious complication of HG due to **Vitamin B1 (Thiamine)** deficiency. Always replenish Thiamine before giving IV Dextrose. * **Electrolyte Imbalance:** Most common pattern is **Hypokalemic Hypochloremic Metabolic Alkalosis**. * **First-line Pharmacotherapy:** Pyridoxine (Vitamin B6) ± Doxylamine.

Question 115: Which of the following congenital malformations will most predictably result in oligohydramnios?

A. Anencephaly
B. Pyloric stenosis
C. Renal agenesis (Correct Answer)
D. Tracheoesophageal fistula

Explanation: ### Explanation The volume of amniotic fluid is a dynamic balance between production and removal. From the second trimester onwards, **fetal urine** becomes the primary source of amniotic fluid, while **fetal swallowing** is the primary route of removal. **Why Renal Agenesis is Correct:** In cases of **bilateral renal agenesis** (Potter’s Syndrome), there is a complete failure of fetal urine production. Since the primary source of amniotic fluid is absent, severe **oligohydramnios** (Amniotic Fluid Index < 5 cm) inevitably occurs. This lack of fluid leads to secondary complications like pulmonary hypoplasia and limb deformities due to uterine compression. **Why Other Options are Incorrect:** * **Anencephaly:** This condition typically results in **polyhydramnios**. The absence of the swallowing reflex (due to neural defects) and the transudation of fluid from the exposed meninges lead to an accumulation of fluid. * **Pyloric Stenosis:** While it involves a gastrointestinal obstruction, it occurs late or postnatally and does not significantly impair fetal swallowing in utero. Therefore, it is not a classic cause of polyhydramnios or oligohydramnios. * **Tracheoesophageal Fistula (TEF):** This often results in **polyhydramnios**. If the fistula prevents the fetus from effectively swallowing and absorbing amniotic fluid through the GI tract, the fluid accumulates in the gestational sac. **NEET-PG Clinical Pearls:** * **Potter’s Sequence:** Remember the mnemonic **POTTER** (Pulmonary hypoplasia, Oligohydramnios, Twisted face, Twisted skin, Extremity defects, Renal agenesis). * **Amniotic Fluid Index (AFI):** Normal range is 5–25 cm. <5 cm is oligohydramnios; >25 cm is polyhydramnios. * **Drug Link:** Maternal intake of **ACE inhibitors** or **NSAIDs** in the second/third trimester can also cause oligohydramnios by reducing fetal renal perfusion.

Question 116: Obesity in pregnancy causes all of the following complications except?

A. Abnormal uterine action
B. Fetal neural tube defect
C. Precipitate labor (Correct Answer)
D. Venous thrombosis

Explanation: **Explanation:** Obesity in pregnancy (BMI >30 kg/m²) is associated with significant maternal and fetal morbidity. The correct answer is **Precipitate labor** because obesity is actually a risk factor for **prolonged or obstructed labor**, not rapid delivery. **1. Why "Precipitate Labor" is the correct answer (the "Except"):** Obesity leads to an increased accumulation of soft tissue in the pelvis and is often associated with larger fetuses (macrosomia). This increases the risk of **cephalopelvic disproportion (CPD)** and **abnormal uterine action** (inefficient contractions). Consequently, obese women have a higher incidence of prolonged first and second stages of labor and a significantly higher rate of Cesarean sections. Precipitate labor (labor lasting <3 hours) is not a feature of obesity. **2. Why the other options are complications of obesity:** * **Abnormal uterine action:** Excess adipose tissue is thought to interfere with myometrial efficiency, potentially due to altered cholesterol levels or inflammatory cytokines, leading to dysfunctional labor. * **Fetal neural tube defects (NTDs):** Obesity is a known independent risk factor for NTDs. This may be due to metabolic derangements (hyperinsulinemia) or difficulty in achieving adequate folic acid levels. * **Venous thrombosis:** Pregnancy is a hypercoagulable state; obesity adds to this risk by causing venous stasis and increased pro-inflammatory markers, making it a major risk factor for VTE. **NEET-PG High-Yield Pearls:** * **Most common complication:** Gestational Diabetes Mellitus (GDM) and Preeclampsia. * **Fetal risks:** Macrosomia, NTDs, and increased risk of stillbirth. * **Anesthetic risk:** Obese patients have a higher risk of difficult intubation and spinal/epidural failure. * **Postpartum risk:** Increased incidence of Postpartum Hemorrhage (PPH) and wound infections.

Question 117: Highest transmission of hepatitis B from mother to fetus occurs if the mother is infected during which period?

A. 1st trimester
B. 2nd trimester
C. 3rd trimester (Correct Answer)
D. At the time of implantation

Explanation: **Explanation:** The transmission of Hepatitis B Virus (HBV) from mother to fetus (vertical transmission) is highly dependent on the gestational age at the time of maternal infection. **Why the 3rd Trimester is Correct:** The risk of vertical transmission increases as pregnancy progresses. If a mother acquires acute Hepatitis B during the **third trimester**, the transmission rate is as high as **70% to 90%**. This is primarily because the placental barrier becomes more permeable toward the end of pregnancy, and there is an increased likelihood of micro-transfusions during late-term uterine contractions or subclinical placental leaks. Furthermore, most neonatal infections occur during delivery (peripartum) through contact with infected maternal blood and vaginal secretions. **Analysis of Incorrect Options:** * **1st Trimester:** The risk of transmission is lowest here, approximately **10%**. The placental barrier is thicker and more robust in early pregnancy, providing better protection against viral passage. * **2nd Trimester:** The risk is intermediate, roughly **25-30%**. While higher than the first trimester, it does not reach the peak levels seen in late pregnancy. * **At the time of implantation:** There is no clinical evidence suggesting significant HBV transmission during the implantation phase; the primary concern is hematogenous spread or exposure during birth. **High-Yield Clinical Pearls for NEET-PG:** * **HBeAg Status:** The presence of HBeAg (indicating high viral replication) in the mother is the strongest predictor of transmission. If the mother is HBsAg (+) and HBeAg (+), the risk of the infant becoming a chronic carrier is 90%. * **Prevention:** To prevent vertical transmission, the neonate must receive both the **HBV Vaccine** and **Hepatitis B Immunoglobulin (HBIG)** within 12 hours of birth. * **Breastfeeding:** HBV is not a contraindication to breastfeeding if the infant receives the appropriate immunoprophylaxis at birth.

Question 118: What is the most common heart disease in pregnancy?

A. Atrial Septal Defect (ASD)
B. Eisenmenger's syndrome
C. Mitral Stenosis (MS) (Correct Answer)
D. Aortic Stenosis (AS)

Explanation: **Explanation:** In the context of pregnancy, **Mitral Stenosis (MS)** remains the most common valvular heart disease encountered worldwide, particularly in developing countries like India. It is almost exclusively a sequela of **Rheumatic Heart Disease (RHD)**. During pregnancy, the physiological increase in cardiac output (30–50%) and heart rate shortens the diastolic filling time. In MS, this leads to increased left atrial pressure, which can precipitate pulmonary edema, making it the most common cause of maternal cardiac morbidity. **Analysis of Options:** * **Mitral Stenosis (MS):** Correct. RHD accounts for nearly 90% of organic heart disease in pregnancy in many regions, with MS being the predominant lesion. * **Atrial Septal Defect (ASD):** While ASD is the most common **congenital** heart disease (CHD) diagnosed in adults/pregnancy, it is less frequent overall than RHD-related MS. * **Eisenmenger's Syndrome:** This is a severe complication of untreated left-to-right shunts. While it carries the **highest mortality risk** (30–50%) in pregnancy, it is relatively rare. * **Aortic Stenosis (AS):** This is significantly less common in the reproductive age group compared to mitral lesions and is generally better tolerated unless severe. **High-Yield Clinical Pearls for NEET-PG:** * **Most common heart disease overall:** Mitral Stenosis (Rheumatic). * **Most common Congenital Heart Disease (CHD):** ASD (Secundum type). * **Highest mortality risk:** Eisenmenger’s Syndrome, followed by Primary Pulmonary Hypertension and Marfan Syndrome with aortic involvement. * **Critical periods for heart failure:** 28–32 weeks (peak blood volume), during labor (second stage), and immediately postpartum (autotransfusion from the uterus).

Question 119: Which one of the following is NOT a feature of severe pre-eclampsia?

A. BP 160/110 mmHg
B. Visual disturbances
C. Oliguria
D. Thrombocytosis (Correct Answer)

Explanation: **Explanation:** Pre-eclampsia is defined as new-onset hypertension (≥140/90 mmHg) and proteinuria (or organ dysfunction) after 20 weeks of gestation. The distinction between pre-eclampsia and **severe pre-eclampsia** is critical for management decisions. **Why Thrombocytosis is the correct answer:** In severe pre-eclampsia, the underlying pathophysiology involves widespread endothelial damage and microangiopathic hemolytic anemia. This leads to **Thrombocytopenia** (platelet count <100,000/mm³), not thrombocytosis. Low platelets occur due to increased consumption and destruction of platelets within the damaged vasculature. **Analysis of Incorrect Options (Features of Severe Pre-eclampsia):** * **BP 160/110 mmHg:** A systolic BP ≥160 mmHg or diastolic BP ≥110 mmHg on two occasions at least 4 hours apart is a diagnostic criterion for severe features. * **Visual Disturbances:** New-onset cerebral or visual disturbances (e.g., photopsia, scotomata, blurred vision) indicate cerebral edema or occipital lobe ischemia, marking severe disease. * **Oliguria:** Reduced urine output (<500 mL in 24 hours) or a progressive rise in serum creatinine (>1.1 mg/dL) signifies significant renal impairment. **NEET-PG High-Yield Pearls:** * **HELLP Syndrome:** A severe variant characterized by **H**emolysis, **E**levated **L**iver enzymes, and **L**ow **P**latelets. * **Drug of Choice:** Magnesium Sulfate ($MgSO_4$) is the gold standard for preventing and treating eclamptic seizures. * **Definitive Treatment:** Delivery of the fetus and placenta is the only cure for pre-eclampsia. * **Proteinuria:** While proteinuria is a diagnostic feature of pre-eclampsia, the *amount* of proteinuria (formerly >5g) is no longer used to define "severe" features in current ACOG guidelines, though it remains a clinical marker.

Question 120: A pregnant female with chronic hypertension whose blood pressure is controlled with antihypertensives should ideally be delivered at which gestational age?

A. 38-39 weeks
B. 37-39 weeks (Correct Answer)
C. 36-37 weeks
D. 35-36 weeks

Explanation: **Explanation:** The management of chronic hypertension in pregnancy focuses on balancing the risks of intrauterine growth restriction (IUGR) and placental abruption against the risks of neonatal prematurity. **Why Option B is Correct:** According to ACOG and standard obstetric guidelines, women with **chronic hypertension** that is **well-controlled** with medication and who do not develop superimposed preeclampsia should be delivered between **37 0/7 and 39 6/7 weeks** of gestation. Delivery during this window (early term to full term) minimizes the risk of stillbirth while ensuring fetal lung maturity and reducing neonatal morbidity associated with late-preterm birth. **Analysis of Incorrect Options:** * **Option A (38-39 weeks):** While delivery in this window is acceptable, it is too narrow. The guidelines specifically allow for delivery starting at 37 weeks. * **Option C (36-37 weeks):** This is the timing for chronic hypertension that is **difficult to control** or associated with mild complications. For well-controlled cases, delivering before 37 weeks unnecessarily increases the risk of respiratory distress syndrome (RDS). * **Option D (35-36 weeks):** This range is generally reserved for severe complications, such as superimposed preeclampsia with severe features or fetal growth restriction with abnormal dopplers. **High-Yield Clinical Pearls for NEET-PG:** * **Definition:** Chronic hypertension is BP ≥140/90 mmHg predating pregnancy or diagnosed before 20 weeks of gestation. * **Drug of Choice:** Labetalol is generally the first-line antihypertensive; Methyldopa and Nifedipine are also used. **ACE inhibitors and ARBs are strictly contraindicated** due to fetal renal dysgenesis. * **Superimposed Preeclampsia:** If a patient with chronic hypertension develops preeclampsia, delivery is usually indicated at **37 weeks** (without severe features) or **immediately upon diagnosis after 34 weeks** (with severe features).

Practice by Chapter

Fetal Assessment Techniques

Practice Questions

Hypertensive Disorders in Pregnancy

Practice Questions

Intrauterine Growth Restriction

Practice Questions

Multiple Gestation

Practice Questions

Rh Isoimmunization and Other Blood Group Incompatibilities

Practice Questions

Intrauterine Fetal Therapy

Practice Questions

Prenatal Diagnosis and Genetic Counseling

Practice Questions

Placental Abnormalities

Practice Questions

Preterm Labor and Delivery

Practice Questions

Management of Medical Disorders in Pregnancy

Practice Questions

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