Maternal-Fetal Medicine Practice Questions

Q: A 30-year-old pregnant woman visits her obstetrician for prenatal care. The patient reports that two of her three children had "yellow jaundice" at birth, and her youngest child was severely jaundiced and required two blood transfusions. Prenatal laboratory tests reveal the mother is blood type O, Rh negative, and her husband is blood type A, Rh positive. The obstetrician obtains amniotic fluid at 36 weeks of gestation to determine if the fetus is mature enough for preterm delivery. Which of the following quantitative analyses of amniotic fluid is most likely used as an indicator of fetal lung maturity?

Lecithin. **Explanation:** The correct answer is **Lecithin (D)**. **1. Why Lecithin is Correct:** The clinical scenario describes a case of **Rh isoimmunization** (Rh-negative mother, Rh-positive father, and a history of progressively worsening neonatal jaundice). In such cases, early delivery may be necessary if fetal hemolysis is severe. To ensure the fetus can survive outside the womb, **Fetal Lung Maturity (FLM)** must be assessed. Lecithin (dipalmitoylphosphatidylcholine) is the primary component of **pulmonary surfactant**. Its concentration in amniotic fluid increases significantly after 34–35 weeks of gestation. The **Lecithin/Sphingomyelin (L/S) ratio** is a classic gold standard for FLM; a ratio **>2.0** typically indicates mature lungs and a low risk of Respiratory Distress Syndrome (RDS). **2. Why Other Options are Incorrect:** * **A. Absorbance at 450 nm ($\Delta OD_{450}$):** This measures **bilirubin** levels in amniotic fluid using spectrophotometry (Liley’s Chart or Queenan Curve). While relevant to this patient's Rh isoimmunization to assess the severity of fetal anemia, it does *not* measure lung maturity. * **B. Alpha-fetoprotein (AFP):** Used to screen for **Neural Tube Defects** (elevated) or chromosomal anomalies like Down syndrome (decreased). * **C. Creatinine:** Amniotic fluid creatinine levels reflect **fetal renal maturity** and muscle mass, not pulmonary status. **3. Clinical Pearls for NEET-PG:** * **Phosphatidylglycerol (PG):** Its presence is the most reliable indicator of lung maturity, especially in **diabetic mothers**, where the L/S ratio may be falsely reassuring. * **Amniostat-FLM:** An immunological test for PG. * **Lamellar Body Count (LBC):** A rapid, automated test; a count **>30,000–50,000/µL** indicates maturity. * **Shake Test (Foam Stability Index):** A bedside screening test for surfactant.

Q: A female has a history of 6 weeks amenorrhea, and ultrasound shows no sac. Serum beta-hCG is 1000 IU/L. What is the next step in the management of this patient?

Repeat hCG after 48 hours. ### Explanation The management of a pregnancy of unknown location (PUL) depends on the **Discriminatory Zone**, which is the serum beta-hCG level above which an intrauterine gestational sac should be visible on ultrasound. For Transvaginal Sonography (TVS), this threshold is typically **1500–2000 IU/L**. **1. Why Option B is Correct:** In this patient, the beta-hCG is **1000 IU/L**, which is below the discriminatory zone. Since the ultrasound is inconclusive (no sac seen), we cannot differentiate between an early viable intrauterine pregnancy, a failing intrauterine pregnancy, or an ectopic pregnancy. The standard protocol is to **repeat serum beta-hCG after 48 hours** to assess the "doubling time." A rise of at least 35–53% suggests a viable intrauterine pregnancy, while a plateau or sub-optimal rise raises suspicion for an ectopic pregnancy. **2. Why Other Options are Incorrect:** * **Option A (Medical Management):** Administering Methotrexate or surgical intervention is premature. Without a confirmed diagnosis of ectopic pregnancy or a non-viable pregnancy above the discriminatory zone, medical management risks terminating a potentially viable early pregnancy. * **Option C (Repeat hCG after 1 week):** A one-week interval is too long. Ectopic pregnancies can rupture quickly; monitoring every 48 hours is essential for patient safety and timely diagnosis. **Clinical Pearls for NEET-PG:** * **Discriminatory Zone:** TVS = 1500–2000 IU/L; Transabdominal Scan (TAS) = 6000–6500 IU/L. * **Doubling Time:** In 85% of viable pregnancies, hCG levels rise by ≥66% every 48 hours (though 35% is the minimum acceptable rise). * **Empty uterus + hCG >2000 IU/L:** Highly suggestive of ectopic pregnancy or recent complete abortion. * **Most common site of ectopic pregnancy:** Ampulla of the Fallopian tube.

Q: What type of placental insertion is shown?

Battledore Placenta. ***Battledore Placenta*** - **Marginal cord insertion** where the umbilical cord inserts at the edge or margin of the placental disc, resembling a badminton racquet. - Associated with increased risk of **cord compression** during labor and potential **fetal growth restriction**, but generally has better outcomes than velamentous insertion. *Velamentous Insertion* - The umbilical cord inserts into the **fetal membranes** rather than the placental disc, with vessels running unprotected through the membranes. - Carries significant risk of **vasa previa** and **vessel rupture** during labor, leading to potential fetal hemorrhage and death. *Normal* - **Central cord insertion** occurs in the middle third of the placental disc, providing optimal blood flow distribution. - This is the most common and safest type of insertion, with minimal risk of complications during pregnancy and delivery. *Circumvallate* - A **placental abnormality** where the fetal membranes fold back over the fetal surface, creating a raised white ring around the placental edge. - Associated with increased risk of **placental abruption**, **preterm labor**, and **antepartum hemorrhage**.

Q: A multigravida with previous 2 normal deliveries presents with an unstable lie of the fetus at 34 weeks gestation. What is the most probable cause?

Placenta previa. **Explanation:** **Why Placenta Previa is the Correct Answer:** An **unstable lie** refers to a situation where the fetal presentation frequently changes (e.g., from transverse to oblique to longitudinal) after 34 weeks of gestation. In a multigravida, the most common cause of an unstable lie or a high floating head is a **space-occupying lesion in the lower uterine segment**. Placenta previa (especially the major degrees) prevents the fetal head from engaging in the maternal pelvis, forcing the fetus into an abnormal or unstable lie. It is a classic "mechanical" obstruction. **Analysis of Incorrect Options:** * **B. Oligohydramnios:** Reduced amniotic fluid typically leads to a **fixed** malpresentation (like breech) because the fetus lacks the fluid volume to move or change positions easily. It does not cause an unstable lie. * **C. Uterine Anomaly:** While anomalies like a bicornuate or septate uterus cause malpresentations, they are more likely to result in a **persistent** malpresentation rather than an unstable one, and are more commonly associated with nulliparity or recurrent pregnancy loss. * **D. Pelvic Tumor:** A large fibroid or ovarian cyst can cause an unstable lie by obstructing the pelvic inlet, but statistically, **placenta previa** is a more frequent and high-yield clinical cause in the third trimester for multigravidas. **High-Yield Clinical Pearls for NEET-PG:** * **Management:** The management of unstable lie at 34 weeks is **expectant** (observation), as many stabilize by 37 weeks. If it persists at 37 weeks, the patient is usually admitted to the hospital. * **Rule of Thumb:** Always exclude placenta previa via ultrasound before performing any internal examination or external cephalic version (ECV) in a patient with an unstable lie or malpresentation. * **Other Causes:** Polyhydramnios, lax abdominal wall (common in multiparity), and contracted pelvis are other significant causes of unstable lie.

Q: Ultrasound is useful in a diabetic mother in all the following except one?

Confirm fetal maturity. **Explanation:** In diabetic pregnancies, ultrasound is a vital tool for monitoring, but it is **not reliable for confirming fetal maturity**, particularly lung maturity. 1. **Why Option A is correct:** In diabetic mothers, there is a significant **dissociation between fetal size and functional maturity**. Due to maternal hyperglycemia, the fetus often experiences accelerated growth (macrosomia). An ultrasound may show a large fetus with advanced biometry, but the fetal lungs may still be immature. Hyperinsulinemia in the fetus inhibits the production of surfactant by type II pneumocytes. Therefore, fetal maturity must be confirmed via gestational age dating or amniocentesis (L/S ratio), not ultrasound parameters. 2. **Why the other options are incorrect:** * **Detect fetal malformation (B):** Diabetic mothers have a higher risk of congenital anomalies (e.g., Cardiac defects, Neural Tube Defects, Caudal Regression Syndrome). Targeted USG (Level II scan) is the gold standard for screening. * **Detect hydramnios (C):** Polyhydramnios is common in poorly controlled diabetes due to fetal osmotic diuresis (fetal polyuria). USG is used to measure the Amniotic Fluid Index (AFI). * **Diagnose hydrocephalus (D):** Hydrocephalus is one of the CNS malformations associated with pre-gestational diabetes and is easily diagnosed via ultrasound. **Clinical Pearls for NEET-PG:** * **Most common anomaly** in diabetic pregnancy: Cardiac defects (specifically VSD). * **Most specific anomaly:** Caudal Regression Syndrome (Sacral Agenesis). * **Best time for anomaly scan:** 18–20 weeks. * **Lecithin/Sphingomyelin (L/S) ratio:** In diabetic mothers, a ratio of >2.0 may still be associated with Respiratory Distress Syndrome (RDS); hence, the presence of **Phosphatidylglycerol (PG)** is a more reliable indicator of lung maturity.

Q: In a G2P1, Rh-negative mother with a previous history of hydrops fetalis, the indirect Coombs test (ICT) is positive at 20 weeks gestation. What is the next line of management?

Middle cerebral artery (MCA) Doppler ultrasound. **Explanation:** In a sensitized Rh-negative pregnancy (ICT positive), the primary goal is to monitor for **fetal anemia**. 1. **Why MCA Doppler is correct:** The Middle Cerebral Artery (MCA) Peak Systolic Velocity (PSV) is the non-invasive "Gold Standard" for detecting fetal anemia. In anemic fetuses, blood viscosity decreases and cardiac output increases, leading to a higher velocity of blood flow. A value **>1.5 MoM (Multiples of Median)** indicates severe anemia and the need for intervention. It has replaced invasive methods like amniocentesis due to its high sensitivity and non-invasive nature. 2. **Why other options are incorrect:** * **Amniocentesis (Liley’s Chart):** Previously used to measure bilirubin (ΔOD450), it is now obsolete for this purpose because it is invasive and less accurate than MCA Doppler, especially before 27 weeks. * **Cordocentesis:** This is the gold standard for *confirming* fetal hemoglobin levels, but it is an invasive procedure with a risk of feto-maternal hemorrhage. It is only performed if MCA Doppler indicates severe anemia (>1.5 MoM). * **Exchange Transfusion:** This is a neonatal procedure performed after birth to treat hyperbilirubinemia. The intrauterine equivalent is **Intrauterine Transfusion (IUT)**, which is only done after anemia is confirmed via cordocentesis. **Clinical Pearls for NEET-PG:** * **Critical Titer:** If ICT titer is **<1:16**, repeat every 2–4 weeks. If **≥1:16**, initiate MCA Doppler. * **First-line screening:** MCA Doppler is the first-line investigation for fetal anemia in sensitized mothers. * **Hydrops Fetalis:** Occurs when fetal hemoglobin falls below 7g/dL (or a 70% deficit).

Q: A 30-year-old obese woman with diabetes mellitus presents at 19 weeks' gestation. She notes recent lack of adherence to her diabetic regimen but is now motivated to improve. Her ophthalmologic examination and ECG are normal. Urinalysis is negative for proteinuria. Laboratory studies show: Hemoglobin A1c: 10.8%; Glucose: 222 mg/dL; TSH: 1.0 mIU/mL; Free T4: 1.7 ng/dL; Creatinine: 1.1 mg/dL. In which of the following conditions is the risk of development the same in diabetics as in the general population?

Congenital adrenal hyperplasia. **Explanation:** The core concept tested here is the specific spectrum of maternal and fetal complications associated with pre-gestational diabetes mellitus (PGDM). **Why Option C is Correct:** **Congenital Adrenal Hyperplasia (CAH)** is an autosomal recessive genetic disorder involving enzyme deficiencies (most commonly 21-hydroxylase) in the steroidogenesis pathway. Its occurrence is determined at conception by parental genotype and is **not influenced by the maternal metabolic environment** or glycemic control. Therefore, the risk remains the same as in the general population. **Why Other Options are Incorrect:** * **A. Asymptomatic Bacteriuria (ASB):** Pregnant women with diabetes have a significantly higher prevalence of ASB due to glucosuria (which promotes bacterial growth) and autonomic bladder dysfunction. If untreated, they have a higher risk of progression to pyelonephritis. * **B. Preeclampsia:** Diabetes is a major risk factor for preeclampsia. The risk is further increased in patients with high HbA1c, obesity, or underlying vasculopathy (White’s Classification R/F). * **D. Postpartum Hemorrhage (PPH):** Diabetics are at increased risk for PPH due to two main factors: **Uterine atony** (caused by overdistension from fetal macrosomia or polyhydramnios) and an increased rate of **instrumental/cesarean deliveries**. **High-Yield NEET-PG Pearls:** * **HbA1c & Malformations:** An HbA1c >10% (as seen in this patient) is associated with a >20% risk of congenital anomalies. * **Most Common Anomaly:** Cardiac defects (specifically Ventricular Septal Defect). * **Most Specific Anomaly:** Caudal Regression Syndrome (Sacral Agenesis). * **Target HbA1c:** Ideally <6.5% pre-conception to minimize the risk of structural anomalies (which occur during organogenesis in the first trimester).

Q: Which of the following is NOT true about gestational diabetes mellitus complicating pregnancy?

Brain enlargement as a part of macrosomia. **Explanation:** In Gestational Diabetes Mellitus (GDM), maternal hyperglycemia leads to fetal hyperglycemia, which stimulates the fetal pancreas to secrete excess insulin. Insulin acts as a potent growth hormone in utero, leading to **macrosomia**. However, this growth is **asymmetric**. While there is organomegaly of the liver, heart, and adrenals, and increased subcutaneous fat, the **brain is characteristically spared** and does not enlarge. Therefore, brain enlargement is NOT a feature of diabetic macrosomia. **Analysis of other options:** * **Hyperglycemia in the infant (Option B):** This is a tricky distractor. While the neonate typically experiences *hypoglycemia* after birth (due to persistent hyperinsulinism once the glucose supply is cut), the fetus itself is **hyperglycemic** in utero as glucose crosses the placenta freely. (Note: In many clinical contexts, "infant" refers to the newborn, making this a common point of confusion; however, in the context of GDM complications, brain sparing is the definitive "false" statement). * **First-trimester abortion (Option C):** Poorly controlled pre-gestational diabetes is a known risk factor for spontaneous abortion and congenital anomalies (like Sacral Agenesis). * **Unexplained fetal death (Option D):** Stillbirths, often occurring after 36 weeks, are a classic complication of uncontrolled GDM, thought to be due to fetal acidosis or hyperglycemia-induced hypoxia. **High-Yield Pearls for NEET-PG:** * **Macrosomia Definition:** Birth weight >4000g or >4500g. * **Pedersen Hypothesis:** Maternal hyperglycemia → Fetal hyperglycemia → Fetal hyperinsulinemia → Macrosomia. * **Most common anomaly:** Cardiac anomalies (specifically VSD/TGA). * **Most specific anomaly:** Caudal Regression Syndrome (Sacral Agenesis). * **Neonatal Metabolic Complications:** Hypoglycemia, Hypocalcemia, Hypomagnesemia, and Hyperbilirubinemia.

Question 1

A 30-year-old pregnant woman visits her obstetrician for prenatal care. The patient reports that two of her three children had "yellow jaundice" at birth, and her youngest child was severely jaundiced and required two blood transfusions. Prenatal laboratory tests reveal the mother is blood type O, Rh negative, and her husband is blood type A, Rh positive. The obstetrician obtains amniotic fluid at 36 weeks of gestation to determine if the fetus is mature enough for preterm delivery. Which of the following quantitative analyses of amniotic fluid is most likely used as an indicator of fetal lung maturity?

Accepted Answer

Lecithin

Answer

Absorbance at 450 nm

Answer

Alpha-fetoprotein

Answer

Creatinine

Question 2

An HIV-infected pregnant woman presents for her 36-week prenatal visit. Which of the following discussion points regarding delivery is true?

Accepted Answer

If her viral load is > 1,000 copies/mL, she will be scheduled for a cesarean delivery at 38 weeks.

Answer

All HIV-infected women should have a cesarean delivery.

Answer

She may have a vaginal delivery only if her viral load is < 100 copies/mL.

Answer

She can deliver vaginally regardless of viral load because she is on highly active antiretroviral therapy.

Question 3

A female has a history of 6 weeks amenorrhea, and ultrasound shows no sac. Serum beta-hCG is 1000 IU/L. What is the next step in the management of this patient?

Accepted Answer

Repeat hCG after 48 hours

Answer

Medical management

Answer

Repeat hCG after 1 week

Answer

None of the above

Question 4

What type of placental insertion is shown?

Accepted Answer

Battledore Placenta

Answer

Velamentous Insertion

Answer

Normal

Answer

Circumvallate

Question 5

Which of the following statements concerning polyhydramnios is true?

Accepted Answer

Complications include placental abruption, uterine dysfunction, and postpartum hemorrhage.

Answer

Acute polyhydramnios always leads to labor at the usual time.

Answer

The incidence of associated malformations is approximately 3%.

Answer

Maternal edema of the vulva and lower limbs is rare.

Question 6

A multigravida with previous 2 normal deliveries presents with an unstable lie of the fetus at 34 weeks gestation. What is the most probable cause?

Accepted Answer

Placenta previa

Answer

Oligohydramnios

Answer

Uterine anomaly

Answer

Pelvic tumor

Question 7

Ultrasound is useful in a diabetic mother in all the following except one?

Accepted Answer

Confirm fetal maturity

Answer

Detect fetal malformation

Answer

Detect hydramnios

Answer

Diagnose hydrocephalus

Question 8

In a G2P1, Rh-negative mother with a previous history of hydrops fetalis, the indirect Coombs test (ICT) is positive at 20 weeks gestation. What is the next line of management?

Accepted Answer

Middle cerebral artery (MCA) Doppler ultrasound

Answer

Amniocentesis for bilirubin estimation

Answer

Exchange transfusion

Answer

Cordocentesis

Question 9

A 30-year-old obese woman with diabetes mellitus presents at 19 weeks' gestation. She notes recent lack of adherence to her diabetic regimen but is now motivated to improve. Her ophthalmologic examination and ECG are normal. Urinalysis is negative for proteinuria. Laboratory studies show: Hemoglobin A1c: 10.8%; Glucose: 222 mg/dL; TSH: 1.0 mIU/mL; Free T4: 1.7 ng/dL; Creatinine: 1.1 mg/dL. In which of the following conditions is the risk of development the same in diabetics as in the general population?

Accepted Answer

Congenital adrenal hyperplasia

Answer

Asymptomatic bacteriuria

Answer

Preeclampsia

Answer

Postpartum hemorrhage after delivery

Question 10

Which of the following is NOT true about gestational diabetes mellitus complicating pregnancy?

Accepted Answer

Brain enlargement as a part of macrosomia

Answer

Hyperglycemia in the infant

Answer

First-trimester abortion

Answer

Unexplained fetal death

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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