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 a blighted ovum?

Avascular villi. ### Explanation A **blighted ovum**, also known as an **anembryonic pregnancy**, occurs when a fertilized egg attaches to the uterine wall, but the embryo fails to develop or resorbs after development has started. **1. Why "Avascular Villi" is Correct:** In a blighted ovum, the gestational sac and trophoblastic tissue continue to grow for a period, but because there is no functioning embryo, there is no established fetal circulation. Histologically, this manifests as **avascular villi** (chorionic villi lacking fetal blood vessels). These villi often undergo hydropic degeneration (swelling), though not to the extent seen in a molar pregnancy. The absence of fetal vessels is the hallmark pathological finding. **2. Analysis of Incorrect Options:** * **Option A (Synaptic knobs):** This is a distractor. Synaptic knobs are anatomical structures found at the ends of axons in the nervous system, unrelated to placental pathology. * **Option C (Intervillous hemorrhage):** While hemorrhage can occur during any miscarriage (spontaneous abortion), it is a non-specific finding. It refers to bleeding between the villi and is not the defining histological characteristic of a blighted ovum. **3. NEET-PG High-Yield Pearls:** * **Diagnosis:** On ultrasound, a blighted ovum is diagnosed when the **Mean Sac Diameter (MSD) is ≥25 mm** without a visible embryo (transvaginal scan). * **Commonest Cause:** Chromosomal abnormalities, most frequently **Autosomal Trisomies** (Trisomy 16 being the most common). * **Clinical Presentation:** The patient may have symptoms of early pregnancy (positive HCG), followed by minor spotting or a routine ultrasound showing an empty sac. * **Management:** Options include expectant management, medical evacuation (Misoprostol), or surgical evacuation (MVA/D&C).

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.

Q: Recurrent abortion in the first trimester is most often due to what cause?

Chromosomal abnormalities. **Explanation:** **1. Why Chromosomal Abnormalities are the Correct Answer:** Chromosomal abnormalities are the single most common cause of spontaneous pregnancy loss, especially in the **first trimester** (up to 12 weeks). In cases of recurrent pregnancy loss (RPL), parental chromosomal rearrangements (like balanced translocations) or sporadic embryonic aneuploidy account for the majority of early losses. Among these, **Autosomal Trisomy** is the most frequent specific chromosomal anomaly found in abortuses, followed by Monosomy X (Turner syndrome) and Polyploidy. **2. Analysis of Incorrect Options:** * **B. Uterine Anomaly:** Structural issues (e.g., septate uterus, cervical incompetence, or fibroids) are significant causes of recurrent abortion but are more characteristically associated with **second-trimester** losses rather than early first-trimester ones. * **C. Hormonal Disturbance:** Conditions like Luteal Phase Defect (LPD), uncontrolled Diabetes Mellitus, and Thyroid disorders can cause miscarriage. However, statistically, they occur less frequently than genetic factors in the first trimester. * **D. Infection:** While certain infections (TORCH, Mycoplasma) can cause sporadic pregnancy loss, they are **rarely** a cause of recurrent abortion, as the mother usually develops immunity after the initial exposure. **3. Clinical Pearls for NEET-PG:** * **Most common Trisomy in abortus:** Trisomy 16. * **Most common single chromosomal anomaly:** Monosomy X (45,X). * **Investigation of choice for RPL:** Karyotyping of both parents to rule out balanced translocations. * **Timing:** If the question specifies "Second Trimester," the most common cause shifts toward **Anatomical/Uterine factors** (specifically Cervical Incompetence).

Question 1

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 2

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 3

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 4

What is a blighted ovum?

Accepted Answer

Avascular villi

Answer

Synaptic knobs

Answer

Intervillous hemorrhage

Answer

None of the above

Question 5

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 6

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 7

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 8

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

Question 9

A patient at 22 weeks gestation is diagnosed with IUD which occurred at 17 weeks but did not have a miscarriage. This patient is at increased risk for which of the following?

Accepted Answer

Consumptive coagulopathy with hypofibrinogenemia

Answer

Septic abortion

Answer

Recurrent abortion

Answer

Future infertility

Question 10

Recurrent abortion in the first trimester is most often due to what cause?

Accepted Answer

Chromosomal abnormalities

Answer

Uterine anomaly

Answer

Hormonal disturbance

Answer

Infection

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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