Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine Indian Medical PG Practice Questions and MCQs

Question 461: Which of the following tests is used to estimate the amount of feto-maternal hemorrhage?

A. Coombs' test
B. Kleihauer Betke test (Correct Answer)
C. Lily's spectrophotometer
D. Schrill's test

Explanation: **Explanation:** The **Kleihauer-Betke (KB) test** is the gold standard for quantifying the volume of feto-maternal hemorrhage (FMH). It is based on the principle of **acid elution**. Fetal hemoglobin (HbF) is resistant to acid elution, whereas adult hemoglobin (HbA) is sensitive. When a maternal blood smear is treated with acid and stained, adult RBCs appear as pale "ghost cells," while fetal RBCs remain dark pink. By counting the ratio of fetal to maternal cells, the volume of FMH can be calculated using the formula: *Volume of FMH (mL) = (% of fetal cells × 50).* This is clinically vital for calculating the required dose of Anti-D immunoglobulin in Rh-negative mothers. **Analysis of Incorrect Options:** * **Coombs' test:** Used to detect antibodies against RBCs. The Indirect Coombs' Test (ICT) screens for maternal sensitization, while the Direct Coombs' Test (DCT) detects antibodies on the newborn's RBCs (e.g., in Hemolytic Disease of the Newborn). * **Liley’s Spectrophotometry:** Historically used to assess the severity of fetal hemolysis by measuring **bilirubin levels** in amniotic fluid (at 450 nm) and plotting them on a Liley chart. * **Schrill's test:** This is a distractor; it is not a standard test in OBGYN. (Note: It is often confused with the *Schilling test* used for Vitamin B12 absorption). **High-Yield Clinical Pearls for NEET-PG:** * **Screening vs. Quantification:** The **Rosette test** is the initial qualitative screening test for FMH. If positive, the **KB test** is performed for quantification. * **Anti-D Dosing:** One 300 mcg vial of Anti-D neutralizes **30 mL** of fetal whole blood (or 15 mL of packed RBCs). * **Alternative:** Flow cytometry is increasingly replacing the KB test due to better precision and less inter-observer variability.

Question 462: Anti-phospholipid antibodies are not typically tested in which of the following conditions?

A. Intrauterine Growth Restriction (IUGR)
B. Mild Preeclampsia
C. Recurrent Abortion
D. Polyhydramnios (Correct Answer)

Explanation: **Explanation:** The core pathophysiology of **Antiphospholipid Antibody Syndrome (APS)** in pregnancy involves a prothrombotic state and placental insufficiency. Antibodies (Lupus anticoagulant, Anti-cardiolipin, and Anti-β2-glycoprotein I) cause thrombosis in the placental vasculature and inhibit trophoblast invasion, leading to decreased placental perfusion. **Why Polyhydramnios is the Correct Answer:** Polyhydramnios (excess amniotic fluid) is typically associated with fetal anomalies (e.g., esophageal atresia), maternal diabetes, or multiple gestations. It is **not** a manifestation of placental vascular compromise. In contrast, APS is characteristically associated with **Oligohydramnios** due to placental insufficiency and reduced fetal renal perfusion. **Analysis of Incorrect Options:** * **Recurrent Abortion:** This is a hallmark of APS. The clinical criteria for APS include ≥3 consecutive spontaneous abortions before 10 weeks, or ≥1 unexplained death of a morphologically normal fetus at ≥10 weeks. * **IUGR:** Placental infarction and reduced nutrient transfer caused by APS lead to fetal growth restriction. * **Mild Preeclampsia:** APS is a significant risk factor for placental-mediated hypertensive disorders. Testing is indicated if a patient develops severe preeclampsia or eclampsia before 34 weeks of gestation. **NEET-PG High-Yield Pearls:** * **Sapporo Criteria:** Diagnosis requires at least one clinical (vascular thrombosis or pregnancy morbidity) and one laboratory criterion (positive tests 12 weeks apart). * **Treatment:** The standard of care for APS in pregnancy is **Low Dose Aspirin (LDA)** and **Low Molecular Weight Heparin (LMWH)**. * **Most Specific Test:** Anti-β2-glycoprotein I is the most specific, while Lupus Anticoagulant is the strongest predictor of pregnancy complications.

Question 463: Of the following potential clinical outcomes of tubal pregnancy, which one is the commonest?

A. Tubal rupture
B. Tubal abortion
C. Vascular insufficiency degenerating the embryo (Correct Answer)
D. Cornual pregnancy reaching term duration

Explanation: **Explanation:** In a tubal ectopic pregnancy, the fallopian tube lacks a well-developed decidua and sufficient space for growth. The **most common clinical outcome** is that the embryo fails to thrive due to **vascular insufficiency**, leading to early degeneration and resorption. This often occurs before the patient even realizes they are pregnant or before clinical symptoms manifest. * **Option C (Correct):** The trophoblast fails to establish a robust blood supply in the thin tubal wall. This leads to early embryonic death, followed by the formation of a tubal mole or complete resorption. * **Option A (Incorrect):** Tubal rupture is a dramatic and life-threatening complication, but it is statistically less common than early degeneration. It typically occurs when the trophoblast invades the muscularis or when the distension exceeds the tube's capacity (common in isthmic pregnancies). * **Option B (Incorrect):** Tubal abortion occurs when the products of conception are expelled through the fimbrial end into the peritoneal cavity. While common in ampullary pregnancies, it ranks second to early degeneration/resorption. * **Option D (Incorrect):** Cornual (interstitial) pregnancies are dangerous because they can grow larger due to the distensibility of the myometrium, but reaching term is extremely rare and carries a high risk of catastrophic rupture. **NEET-PG High-Yield Pearls:** * **Most common site of Ectopic Pregnancy:** Ampulla (70%). * **Most common site for Tubal Rupture:** Isthmus (due to narrow lumen). * **Most common site for Tubal Abortion:** Ampulla. * **Classic Triad:** Amenorrhea, abdominal pain, and vaginal bleeding (present in only 50% of cases). * **Gold Standard Diagnosis:** Transvaginal Ultrasound (TVUS) + Serum $\beta$-hCG (Discriminatory zone: 1500–2000 mIU/mL).

Question 464: A young woman with six weeks amenorrhoea presents with an abdominal mass. Ultrasound shows an empty uterus. What is the most likely diagnosis?

A. Ovarian cyst
B. Ectopic pregnancy (Correct Answer)
C. Complete abortion
D. None of the above

Explanation: ### Explanation **Correct Answer: B. Ectopic pregnancy** The clinical triad of **amenorrhea, abdominal pain, and an empty uterus on ultrasound** in a woman of reproductive age is highly suggestive of an ectopic pregnancy until proven otherwise. At six weeks of gestation, an intrauterine gestational sac should typically be visible via transvaginal sonography (TVS). The presence of an "empty uterus" in a patient with a positive pregnancy test (implied by amenorrhea) and an adnexal/abdominal mass indicates that the blastocyst has implanted outside the uterine cavity—most commonly in the fallopian tube (95%). The "abdominal mass" in this context often represents the ectopic sac, a hematoma, or a ruptured tubal pregnancy with localized collection. **Why other options are incorrect:** * **A. Ovarian cyst:** While an ovarian cyst presents as an abdominal mass, it does not typically cause amenorrhea unless it is a functional corpus luteum cyst of pregnancy. However, the combination of amenorrhea and a mass in a clinical vignette is a classic "red flag" for ectopic pregnancy in exams. * **C. Complete abortion:** In a complete abortion, the uterus would be empty, but there would be a history of heavy vaginal bleeding and passage of products of conception. Crucially, a complete abortion would not present with a persistent abdominal mass. **NEET-PG High-Yield Pearls:** * **Discriminatory Zone:** The serum β-hCG level at which an intrauterine sac should be seen is **1500–2000 mIU/ml** (TVS) or **6500 mIU/ml** (TAS). If the uterus is empty above these levels, suspect ectopic pregnancy. * **Most common site:** Ampulla of the Fallopian tube. * **Gold Standard Diagnosis:** Laparoscopy. * **Classic Sign:** "Ring of Fire" sign (hypervascularity around the adnexal mass) on Doppler ultrasound.

Question 465: Which scenario leads to the most severe Rh-isoimmunization in a fetus?

A. Rh negative mother and Rh positive fetus in the second pregnancy. (Correct Answer)
B. Rh positive mother and Rh negative fetus.
C. Rh positive mother and Rh negative fetus in the 15th pregnancy.
D. Rh positive mother and Rh positive fetus in the second pregnancy.

Explanation: ### Explanation **Concept Overview:** Rh-isoimmunization occurs when an **Rh-negative mother** is exposed to **Rh-positive fetal red blood cells** (usually during delivery of the first pregnancy). This exposure triggers the production of maternal antibodies (IgM initially, then IgG). In subsequent pregnancies with an Rh-positive fetus, maternal **IgG antibodies** cross the placenta and cause fetal hemolysis (Erythroblastosis Fetalis). **Why Option A is Correct:** For isoimmunization to occur, there must be an **antigenic mismatch** where the mother lacks the D-antigen (Rh-negative) and the fetus possesses it (Rh-positive). The first pregnancy usually acts as the "sensitizing" event. The **second pregnancy** is the first one clinically affected by the pre-formed maternal IgG antibodies, leading to severe fetal hemolysis. **Why Other Options are Incorrect:** * **Options B, C, and D:** In all these scenarios, the mother is **Rh-positive**. If the mother is Rh-positive, she already possesses the D-antigen on her RBCs. Therefore, her immune system recognizes the D-antigen as "self" and will not produce anti-D antibodies, regardless of the fetus's Rh status or the number of pregnancies. **High-Yield Clinical Pearls for NEET-PG:** * **Antibody Type:** Only **IgG** (specifically IgG1 and IgG3) crosses the placenta; IgM does not. * **The "Grandmother Theory":** An Rh-negative female infant can be sensitized at her own birth by her Rh-positive mother’s blood. * **Prophylaxis:** Administer **Anti-D Gamma Globulin (300 mcg)** at 28 weeks gestation and within 72 hours of delivery to all non-sensitized Rh-negative mothers. * **Kleihauer-Betke Test:** Used to quantify the volume of fetal-maternal hemorrhage to determine the required dose of Anti-D. * **Screening:** Indirect Coombs Test (ICT) is used to monitor maternal antibody titers. A titer of **1:16** is generally considered the critical threshold.

Question 466: What is the anticoagulant of choice in pregnancy?

A. Heparin (Correct Answer)
B. Warfarin
C. Dicoumarol
D. Phenindione

Explanation: **Explanation:** **Heparin** (both Unfractionated Heparin and Low Molecular Weight Heparin) is the anticoagulant of choice in pregnancy because it has a high molecular weight and is highly polar, meaning it **does not cross the placenta**. Consequently, it poses no risk of teratogenicity or fetal hemorrhage. Low Molecular Weight Heparin (LMWH), such as Enoxaparin, is generally preferred over Unfractionated Heparin (UFH) due to a better safety profile, predictable pharmacokinetics, and lower risk of Heparin-Induced Thrombocytopenia (HIT) and osteoporosis. **Why the other options are incorrect:** * **Warfarin (Option B):** It is a small molecule that readily crosses the placenta. It is teratogenic, especially during the first trimester (6–9 weeks), leading to **Fetal Warfarin Syndrome** (characterized by nasal hypoplasia and stippled epiphyses). In the third trimester, it increases the risk of fetal intracranial hemorrhage. * **Dicoumarol and Phenindione (Options C & D):** These are oral anticoagulants similar to Warfarin. They cross the placenta and are associated with significant fetal risks, making them contraindicated in pregnancy. **High-Yield Clinical Pearls for NEET-PG:** * **Exception for Warfarin:** It may be used in pregnant women with **mechanical heart valves** (especially if the dose is <5mg/day) because the risk of valve thrombosis with Heparin is very high, though it must be switched to Heparin near term. * **Monitoring:** UFH is monitored using **aPTT**, whereas LMWH usually does not require monitoring (if needed, **Anti-Xa levels** are used). * **Labor Management:** Anticoagulants must be discontinued before labor to prevent maternal hemorrhage and to allow for regional anesthesia (epidural).

Question 467: Which of the following risk factors is considered high risk for screening Gestational Diabetes Mellitus (GDM)?

A. Age less than 25 years
B. Normal pre-pregnancy weight
C. Strong family history of type 2 diabetes (Correct Answer)
D. No history of abnormal glucose metabolism

Explanation: **Explanation:** Gestational Diabetes Mellitus (GDM) screening is a critical component of antenatal care. Risk stratification helps identify women who require early testing (at the first prenatal visit) versus routine screening (at 24–28 weeks). **Why Option C is correct:** A **strong family history of Type 2 Diabetes Mellitus** (especially in first-degree relatives) is a well-established high-risk factor. It indicates a genetic predisposition to insulin resistance and beta-cell dysfunction. When the physiological stress of pregnancy-induced insulin resistance (mediated by hormones like Human Placental Lactogen) is added, these women are significantly more likely to develop GDM. **Analysis of Incorrect Options:** * **Option A (Age < 25 years):** Maternal age **greater than 25 years** is considered a risk factor. Younger age (under 25) is generally associated with a lower risk and is a criteria for "low-risk" status. * **Option B (Normal pre-pregnancy weight):** Obesity (BMI > 30 kg/m²) is a major risk factor. A normal BMI is protective and does not categorize a patient as high risk. * **Option D (No history of abnormal glucose metabolism):** A **prior history** of GDM or impaired glucose tolerance is one of the strongest predictors for GDM in subsequent pregnancies. No such history suggests a lower risk profile. **High-Yield Clinical Pearls for NEET-PG:** * **DIPSI Guidelines (India):** Recommends universal screening. A single-step test using **75g oral glucose** is performed, and a 2-hour plasma glucose **≥ 140 mg/dL** is diagnostic of GDM, regardless of the fasting state. * **Other High-Risk Factors:** Polycystic Ovary Syndrome (PCOS), previous birth of a macrosomic infant (>4kg), and belonging to high-prevalence ethnic groups (e.g., South Asians). * **Gold Standard:** While DIPSI is common in India, the **IADPSG criteria** (based on the HAPO study) is the international benchmark.

Question 468: Which of the following medications is the drug of choice for severe preeclampsia?

A. Labetalol (Correct Answer)
B. Metoprolol
C. Alpha-methyldopa
D. Nifedipine

Explanation: **Explanation:** In the management of severe preeclampsia, the primary goal of antihypertensive therapy is to prevent cerebrovascular accidents and maternal heart failure by rapidly reducing blood pressure. **1. Why Labetalol is the Correct Answer:** Labetalol is a combined alpha- and beta-adrenergic blocker. It is considered the **first-line drug of choice** for the acute management of severe hypertension (BP ≥160/110 mmHg) in pregnancy. Its rapid onset of action (5–10 minutes when given IV), excellent safety profile, and ability to lower blood pressure without causing significant reflex tachycardia or reducing uteroplacental blood flow make it the gold standard in emergency obstetric care. **2. Analysis of Incorrect Options:** * **Metoprolol:** This is a cardioselective beta-1 blocker. It is generally avoided in pregnancy as it is associated with a higher risk of fetal growth restriction (FGR) compared to other agents and is not used for acute hypertensive crises. * **Alpha-methyldopa:** While this is the drug of choice for **chronic hypertension** in pregnancy, it is unsuitable for severe preeclampsia/hypertensive crisis due to its slow onset of action (4–6 hours) and sedative side effects. * **Nifedipine:** Oral immediate-release nifedipine is an acceptable alternative for acute BP control; however, Labetalol remains the preferred first-line agent in most international guidelines (ACOG/RCOG) due to its predictable response. **3. High-Yield Clinical Pearls for NEET-PG:** * **Target BP:** Aim to maintain systolic BP between 140–150 mmHg and diastolic BP between 90–100 mmHg. * **Contraindication:** Avoid Labetalol in patients with **asthma** or congestive heart failure. * **Hydralazine:** Previously a first-line agent, it is now considered second-line due to the risk of maternal hypotension and fetal distress. * **Magnesium Sulfate ($MgSO_4$):** Always remember that $MgSO_4$ is the drug of choice for **seizure prophylaxis/treatment**, not for blood pressure control.

Question 469: What is the most common site of ectopic pregnancy in the fallopian tube?

A. Infundibulum
B. Ampulla (Correct Answer)
C. Isthmus
D. Interstitium

Explanation: **Explanation:** Ectopic pregnancy occurs when a fertilized ovum implants outside the normal uterine cavity. The **Fallopian tube** is the most common site for ectopic pregnancy, accounting for approximately **95-97%** of all cases. **1. Why Ampulla is Correct:** The **Ampulla** is the widest and longest part of the fallopian tube, making it the most frequent site for fertilization. Consequently, it is the most common site for ectopic implantation, accounting for approximately **70-80%** of tubal pregnancies. **2. Analysis of Incorrect Options:** * **Infundibulum (approx. 5%):** This is the distal, funnel-shaped portion. Implantation here is less common and often results in tubal abortion. * **Isthmus (approx. 12%):** This is the narrow, muscular portion. While less common than the ampulla, pregnancies here are more likely to result in early rupture (usually by 6-8 weeks) due to the lack of distensibility. * **Interstitium (approx. 2-3%):** This is the segment within the uterine wall. Though the least common tubal site, it is the **most dangerous**. Because the area is highly vascular (near the uterine and ovarian artery anastomosis), rupture here occurs later (12-16 weeks) and can lead to massive, life-threatening hemorrhage. **High-Yield Clinical Pearls for NEET-PG:** * **Overall Most Common Site:** Ampulla of the Fallopian tube. * **Most Common Site for Rupture:** Isthmus (earliest rupture) vs. Interstitial (latest/most severe rupture). * **Classic Triad:** Amenorrhea, abdominal pain, and vaginal bleeding (present in only 50% of cases). * **Gold Standard Investigation:** Transvaginal Ultrasound (TVS) + Serum β-hCG (Correlation with the "Discriminatory Zone"). * **Arias-Stella Reaction:** Hypersecretory endometrium seen on biopsy, which is suggestive of pregnancy but not specific to ectopic.

Question 470: Which of the following tests is done to differentiate between maternal and fetal blood in a case of fetomaternal hemorrhage?

A. Apt test
B. Kleihauer Betke test (Correct Answer)
C. Bubbling test
D. Liley test

Explanation: **Explanation:** The **Kleihauer-Betke (KB) test** is the gold standard for quantifying the extent of fetomaternal hemorrhage (FMH). It is based on the principle of **acid elution**. Fetal hemoglobin (HbF) is resistant to acid elution, whereas adult hemoglobin (HbA) is sensitive. When a maternal blood smear is treated with acid, HbA is leached out of the maternal red cells, leaving them as pale "ghost cells." The fetal red cells retain their hemoglobin and appear dark pink/red under the microscope. This allows for the calculation of the volume of fetal blood in maternal circulation, which is crucial for determining the required dose of Anti-D immunoglobulin. **Analysis of Incorrect Options:** * **Apt test:** This is used to differentiate fetal from maternal blood in cases of **neonatal hematemesis or melena** (e.g., swallowed maternal blood during delivery vs. GI bleed) or vaginal bleeding (Vasa Previa). It uses alkali (NaOH) denaturation. * **Bubbling test (Shake test):** A bedside test used to assess **fetal lung maturity** by checking for the presence of surfactant in amniotic fluid. * **Liley test:** Historically used to manage **Rh isoimmunization** by measuring bilirubin levels in amniotic fluid via spectrophotometry ($\Delta OD_{450}$) to assess the severity of fetal hemolysis. **High-Yield Clinical Pearls for NEET-PG:** * **KB Test Formula:** Volume of FMH (mL) = (Number of fetal cells / Total cells) × 5000 mL. * **Anti-D Dosing:** One 300 mcg dose of Anti-D covers up to **30 mL** of fetal whole blood (or 15 mL of fetal RBCs). * The **Rosette test** is a qualitative screening test for FMH; if positive, it must be followed by the KB test for quantification.

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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