Maternal-Fetal Medicine Practice Questions

Q: A 28-year-old pregnant woman at 26 weeks gestation presents with a 3-day history of increasing shortness of breath. Her past medical history includes well-controlled bronchial asthma. On examination, she is tachypneic and uncomfortable, with a pulse of 110 bpm, respirations of 32/min, and blood pressure of 160/90 mm Hg. Cardiac exam reveals a regular heart rhythm without gallop and a grade 2/6 systolic murmur in the pulmonic area. Lung auscultation is clear. Abdominal examination confirms a 26-week gravid uterus. Laboratory data includes Hb 12 g/dL, Hct 36%, WBC 7.0/uL, BUN 23 mg/dL, creatinine 0.9 mg/dL, sodium 136 mEq/L, and potassium 4.2 mEq/L. Arterial blood gases on room air show pH 7.34, PCO2 34 mm Hg, and PO2 68 mm Hg. Peak expiratory flow rate (PEFR) is 450 L/min. Chest x-rays are available. What is the most likely diagnosis?

Pulmonary embolism. ### Explanation The correct diagnosis is **Pulmonary Embolism (PE)**. Pregnancy is a hypercoagulable state, increasing the risk of venous thromboembolism (VTE) five-fold. **Why Pulmonary Embolism is correct:** The patient presents with sudden-onset tachypnea, tachycardia, and significant hypoxemia ($PO_2$ of 68 mm Hg). A crucial finding here is the **Arterial Blood Gas (ABG)**. In pregnancy, the normal physiological state is a mild respiratory alkalosis (due to progesterone-driven hyperventilation), with a typical $PCO_2$ of 27–32 mm Hg and a pH of 7.40–7.45. A $PCO_2$ of 34 mm Hg and pH of 7.34 in this patient indicates **respiratory acidosis**, signaling respiratory failure and an inability to compensate, which is highly suggestive of a major PE. **Why incorrect options are wrong:** * **Acute Anxiety:** While it causes tachypnea, it would result in respiratory alkalosis (low $PCO_2$, high pH) and would not cause significant hypoxemia ($PO_2$ 68). * **Acute Exacerbation of Bronchial Asthma:** The **Peak Expiratory Flow Rate (PEFR)** of 450 L/min is normal, and lung auscultation is clear (no wheezing), effectively ruling out an asthma attack. * **High-output Heart Failure:** While common in pregnancy, the clear lung fields and absence of a gallop rhythm make this unlikely. The systolic murmur (grade 2/6) is a common physiological finding in pregnancy due to increased blood volume. **High-Yield Clinical Pearls for NEET-PG:** * **ABG in Pregnancy:** Normal $pH$ 7.44, $PCO_2$ ~30 mmHg, $PO_2$ >100 mmHg. A "normal" non-pregnant $PCO_2$ (40 mmHg) in a pregnant woman signifies impending respiratory failure. * **Diagnosis:** The gold standard for PE in pregnancy is **CT Pulmonary Angiography (CTPA)** or V/Q scan. * **Treatment:** Low Molecular Weight Heparin (LMWH) is the drug of choice; Warfarin is contraindicated due to teratogenicity.

Q: A 20-year-old woman, gravida 2, para 0, aboa 1, presents for a prenatal visit at 30 weeks gestation. Her previous ultrasound at 18 weeks confirmed a single fetus appropriate for dates. She reports good fetal movement and has gained 9 kg. Today, her fundal height measures 25 cm, and fetal heart sounds are heard in the right upper quadrant. An obstetric ultrasound reveals an amniotic fluid index (AFI) of 4 cm. Which of the following conditions is most likely associated with this scenario?

Renal agenesis. **Explanation:** The clinical presentation highlights a **lag in fundal height** (25 cm at 30 weeks) and an **Amniotic Fluid Index (AFI) of 4 cm**, which signifies **Oligohydramnios** (defined as AFI < 5 cm or single deepest pocket < 2 cm). **1. Why Renal Agenesis is Correct:** Fetal urine production is the primary source of amniotic fluid starting from the second trimester (around 16 weeks). In cases of **bilateral renal agenesis** (Potter sequence) or renal anomalies, the absence of fetal urine leads to severe oligohydramnios. This results in a smaller-than-expected uterus (lagging fundal height) and can cause fetal crowding, leading to malpresentations (e.g., fetal heart sounds in the upper quadrant suggesting breech). **2. Why Incorrect Options are Wrong:** * **A. Duodenal Atresia:** This condition prevents the fetus from swallowing amniotic fluid, leading to **Polyhydramnios** (AFI > 25 cm), not oligohydramnios. * **B. Open Spina Bifida:** While associated with various anomalies, it does not typically cause oligohydramnios unless there is associated renal dysfunction or premature rupture of membranes. * **C. Tracheoesophageal Fistula:** Similar to duodenal atresia, this impairs the fetal ability to swallow and process amniotic fluid, typically resulting in **Polyhydramnios**. **Clinical Pearls for NEET-PG:** * **Oligohydramnios Causes (DRIPPC):** **D**eath (fetal), **R**enal anomalies, **I**UGR, **P**rom (Premature Rupture of Membranes), **P**ost-term pregnancy, **C**hromosomal anomalies. * **Potter Sequence:** Bilateral renal agenesis → Oligohydramnios → Pulmonary hypoplasia, limb deformities, and flattened facies. * **Fundal Height:** A discrepancy of >3 cm between gestational age and symphysis-fundal height (SFH) warrants an ultrasound to rule out growth restriction or fluid abnormalities.

Q: What is the earliest sign of magnesium toxicity?

Falling oxygen saturation on pulse oximetry. **Explanation:** Magnesium sulfate ($MgSO_4$) is the drug of choice for seizure prophylaxis in pre-eclampsia and control in eclampsia. However, it has a narrow therapeutic index (4–7 mEq/L). **Why Option A is Correct:** Traditionally, the loss of deep tendon reflexes (patellar reflex) was taught as the first clinical sign of toxicity. However, recent clinical evidence and updated protocols highlight that **falling oxygen saturation ($SpO_2 < 95\%$)** on pulse oximetry is the **earliest objective indicator** of magnesium toxicity. This occurs due to the weakening of respiratory muscles and minor changes in alveolar ventilation that precede a visible drop in respiratory rate. **Analysis of Incorrect Options:** * **B. Respiratory Depression:** This occurs at higher serum levels (12–15 mEq/L). While it is a classic sign, it follows the loss of reflexes and the initial drop in $SpO_2$. * **C. Cardiac Arrest:** This is a late and terminal sign of toxicity, typically occurring when serum levels exceed 25 mEq/L. * **D. Anuria:** Magnesium is excreted solely by the kidneys. While oliguria/anuria is a **predisposing factor** that leads to toxicity (due to accumulation), it is not a sign of the toxicity itself. **High-Yield Clinical Pearls for NEET-PG:** * **Order of Toxicity:** $SpO_2$ drop → Loss of Patellar Reflex (8–10 mEq/L) → Respiratory Depression (12–15 mEq/L) → Cardiac Arrest (>25 mEq/L). * **Monitoring:** Always check urine output (>30 ml/hr), respiratory rate (>12/min), and presence of knee jerk before every dose. * **Antidote:** 10 ml of 10% **Calcium Gluconate** administered IV over 10 minutes.

Q: Which of the following statements regarding cholestasis of pregnancy is FALSE?

Serum bilirubin is elevated above 5 mg/dL. **Intrahepatic Cholestasis of Pregnancy (ICP)** is a reversible form of hormonal cholestasis occurring in the late second or third trimester, characterized by intense pruritus and elevated serum bile acids. ### **Explanation of Options:** * **Option A (Correct Answer):** In ICP, while serum bilirubin may be elevated, it is **rarely above 2–5 mg/dL**. A bilirubin level exceeding 5 mg/dL is highly unusual and should prompt an investigation for other causes like viral hepatitis, biliary obstruction, or hemolysis. * **Option B:** Transaminases (ALT/AST) are typically elevated in ICP but remain relatively low compared to viral hepatitis. They are usually **less than 250 IU/L**, though they can occasionally reach up to 500 IU/L. * **Option C:** Pruritus (typically involving palms and soles) is the hallmark symptom and often **precedes the elevation of biochemical markers** (bile acids and LFTs) by several weeks. * **Option D:** ICP is associated with **dyslipidemia**, specifically an increase in total cholesterol, LDL, and triglycerides, likely due to the metabolic impact of cholestasis on lipid processing. ### **Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Elevated **Serum Bile Acids (>10 μmol/L)** is the most sensitive and specific marker. * **Drug of Choice:** **Ursodeoxycholic Acid (UDCA)** – it improves pruritus and lowers bile acid levels. * **Fetal Risks:** ICP is associated with an increased risk of **meconium-stained amniotic fluid, preterm labor, and sudden intrauterine fetal death (IUFD)**, especially when bile acids exceed 40–100 μmol/L. * **Postpartum:** Symptoms and lab values typically resolve within 2–4 weeks after delivery. If they persist, consider primary biliary cholangitis.

Q: What is the primary cause of knots in the umbilical cord?

Fetal movement. ### Explanation **Primary Concept:** True knots of the umbilical cord (*cordis nodus*) occur in approximately 1% of deliveries. The primary etiology is **active fetal movement**, particularly during the second trimester when the volume of amniotic fluid is relatively high compared to the fetus, allowing the fetus to pass through a loop of the cord. **Why Option A is Correct:** Fetal activity is the driving force. Factors that facilitate this include a **long umbilical cord**, polyhydramnios, and small fetal size (allowing more room for maneuvers). While most knots remain loose and asymptomatic, they can tighten during descent in labor. **Analysis of Incorrect Options:** * **Option B:** While a *tight* knot can lead to venous congestion or arterial occlusion, the presence of a knot itself is not a "high risk" for stillbirth in most cases. The perinatal mortality rate is increased (approx. 4-fold), but the majority of cases result in live births. * **Option C:** This is a distractor. Knots are most dangerous in **monoamniotic** twins (not diamniotic) due to cord entanglement between the two fetuses sharing a single sac. * **Option D:** A true knot is **not** an absolute indication for a Cesarean section. Many are diagnosed incidentally postpartum. Management involves close fetal monitoring (CTG); surgery is only indicated if there are signs of fetal distress (e.g., variable decelerations). **High-Yield NEET-PG Pearls:** * **False Knots:** These are simply redundant folds of umbilical vessels or focal accumulations of Wharton’s jelly; they have no clinical significance. * **Risk Factors:** Multiparity, long cords, and monoamniotic twins. * **Diagnosis:** On Color Doppler, a true knot may show the **"hanging man sign."** * **Clinical Sign:** Look for **variable decelerations** on the CTG during labor if the knot tightens.

Question 1

A young married female presents to the emergency department with lower abdominal pain, severe dizziness, and two episodes of syncope in the last 12 hours. On arrival, her blood pressure was 89/40 mm Hg, and standing blood pressure could not be recorded due to near syncope upon sitting. What is the most likely diagnosis to rule out in this patient?

Accepted Answer

Ruptured ectopic pregnancy

Answer

Acute appendicitis

Answer

Torsion of ovary

Answer

Acute pancreatitis

Question 2

A 20-year-old woman complains of sudden onset of right-sided lower abdominal pain and bleeding per vagina. Her last normal menstrual period was 35 days ago. Her blood pressure is 90/70 mmHg and the pulse rate is 100 bpm. There is tenderness and guarding in the right iliac fossa. She denies any sexual intercourse. What is the most appropriate next step in the management?

Accepted Answer

Perform a transvaginal ultrasound scan

Answer

Estimate serum beta hCG levels

Answer

Obtain a surgical opinion to exclude acute appendicitis

Answer

Perform a laparoscopic examination

Question 3

A patient with a history of previous unexplained intrauterine fetal death at term now presents at 9 months of gestation with itching, a bilirubin level of 3 mg/dL, and mildly elevated AST. A diagnosis of intrahepatic cholestasis of pregnancy (IHCP) was made. What is the appropriate management?

Accepted Answer

Ursodeoxycholic acid with induction of labor at 38 weeks and strict intrapartum fetal monitoring

Answer

Elective Cesarean section at 36 weeks

Answer

Symptomatic management and delivery at 40+ weeks

Answer

Fresh frozen plasma transfusion

Question 4

A 28-year-old pregnant woman at 26 weeks gestation presents with a 3-day history of increasing shortness of breath. Her past medical history includes well-controlled bronchial asthma. On examination, she is tachypneic and uncomfortable, with a pulse of 110 bpm, respirations of 32/min, and blood pressure of 160/90 mm Hg. Cardiac exam reveals a regular heart rhythm without gallop and a grade 2/6 systolic murmur in the pulmonic area. Lung auscultation is clear. Abdominal examination confirms a 26-week gravid uterus. Laboratory data includes Hb 12 g/dL, Hct 36%, WBC 7.0/uL, BUN 23 mg/dL, creatinine 0.9 mg/dL, sodium 136 mEq/L, and potassium 4.2 mEq/L. Arterial blood gases on room air show pH 7.34, PCO2 34 mm Hg, and PO2 68 mm Hg. Peak expiratory flow rate (PEFR) is 450 L/min. Chest x-rays are available. What is the most likely diagnosis?

Accepted Answer

Pulmonary embolism

Answer

Acute anxiety

Answer

Acute exacerbation of bronchial asthma

Answer

High-output heart failure

Question 5

A 20-year-old woman, gravida 2, para 0, aboa 1, presents for a prenatal visit at 30 weeks gestation. Her previous ultrasound at 18 weeks confirmed a single fetus appropriate for dates. She reports good fetal movement and has gained 9 kg. Today, her fundal height measures 25 cm, and fetal heart sounds are heard in the right upper quadrant. An obstetric ultrasound reveals an amniotic fluid index (AFI) of 4 cm. Which of the following conditions is most likely associated with this scenario?

Accepted Answer

Renal agenesis

Answer

Duodenal atresia

Answer

Open spina bifida

Answer

Tracheoesophageal fistula

Question 6

A pregnant woman at 12 weeks gestation is exposed to chickenpox and has no prior history of the disease. What is the best management if she is found to be seronegative for varicella-zoster virus antibodies?

Accepted Answer

Administer varicella-zoster immunoglobulin as soon as possible after exposure.

Answer

Administer varicella-zoster vaccine as soon as possible after exposure.

Answer

Termination of pregnancy.

Answer

Treatment with oral acyclovir if infection occurs.

Question 7

What is the earliest sign of magnesium toxicity?

Accepted Answer

Falling oxygen saturation on pulse oximetry

Answer

Respiratory depression

Answer

Cardiac arrest

Answer

Anuria

Question 8

Which of the following statements regarding cholestasis of pregnancy is FALSE?

Accepted Answer

Serum bilirubin is elevated above 5 mg/dL

Answer

Alanine aminotransferase (ALT) is less than 250 IU/L

Answer

Pruritus precedes abnormal laboratory values by weeks

Answer

Dyslipidemia is associated

Question 9

The 'double set up examination' is concerned with which of the following conditions?

Accepted Answer

Placenta previa

Answer

Manual removal of placenta

Answer

Twin pregnancy

Answer

Bicornuate uterus

Question 10

What is the primary cause of knots in the umbilical cord?

Accepted Answer

Fetal movement

Answer

High risk of stillbirth

Answer

Dangerous in diamniotic twins

Answer

Always an indication for Cesarean section

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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