Maternal-Fetal Medicine Practice Questions

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

Kleihauer Betke test. **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.

Q: A 25-year-old G2P1 female has a history of previous preterm birth at 32 weeks. What is the percentage chance of preterm birth in this pregnancy?

15%. **Explanation:** The single most significant risk factor for preterm birth (PTB) is a **prior history of spontaneous preterm birth**. The risk of recurrence increases significantly based on the number and timing of previous episodes. **1. Why 15% is correct:** Statistically, a woman with one previous preterm birth has a **15–17% risk** of recurrence in her subsequent pregnancy. This represents a nearly three-fold increase compared to the baseline risk in the general population (which is approximately 5–10%). If a woman has two prior preterm births, the risk escalates further to approximately 30–35%. **2. Analysis of Incorrect Options:** * **A (5%):** This represents the lower end of the baseline risk for a primigravida or a woman with a previous full-term delivery. * **B (10%):** This is the average global incidence of preterm birth but does not account for the significantly increased risk conferred by a prior history. * **D (25%):** This risk level is typically associated with women who have had **two** previous preterm births, rather than one. **High-Yield Clinical Pearls for NEET-PG:** * **Prophylaxis:** For patients with a history of spontaneous PTB, the standard of care is **17-alpha-hydroxyprogesterone caproate** (starting at 16–24 weeks) or vaginal progesterone. * **Cervical Screening:** Serial transvaginal ultrasound (TVUS) to measure **cervical length** is indicated. A length **<25 mm** before 24 weeks is a strong predictor of PTB. * **Golden Rule:** The earlier the gestational age of the previous preterm birth, the higher the risk of recurrence in the current pregnancy.

Q: What is the key difference between ectopic pregnancy and threatened abortion?

Uterine size corresponds to gestational age. In the context of early pregnancy complications, differentiating between ectopic pregnancy and threatened abortion is a high-yield clinical skill for NEET-PG. **Explanation of the Correct Answer:** In a **threatened abortion**, the pregnancy is intrauterine. Therefore, the **uterine size corresponds to the period of amenorrhea (gestational age)**. In contrast, in an **ectopic pregnancy**, the uterus is typically **smaller** than the period of amenorrhea because the gestational sac is located extra-uterinely (most commonly in the fallopian tube), and the uterus only undergoes minor decidual changes. **Analysis of Incorrect Options:** * **A. Presence of minimal vaginal bleeding:** Both conditions present with spotting or minimal bleeding. In ectopic pregnancy, bleeding is usually dark brown and scanty; in threatened abortion, it is fresh and bright red. * **B. Pain typically follows bleeding:** This is a classic feature of **threatened abortion** (Bleeding → Pain). In **ectopic pregnancy**, the sequence is reversed: **Pain precedes bleeding** (Pain → Bleeding). * **D. Manifests at an early gestational age:** Both conditions typically manifest in the first trimester (6–10 weeks), making this a poor differentiating factor. **NEET-PG High-Yield Pearls:** * **The Classic Triad of Ectopic Pregnancy:** Amenorrhea, abdominal pain, and vaginal bleeding. * **Arias-Stella Reaction:** Hypersecretory endometrium seen on histology in ectopic pregnancy (not pathognomonic, but highly suggestive). * **Discriminatory Zone:** If Serum β-hCG is >1500–2000 mIU/mL and the gestational sac is not visible on Transvaginal Ultrasound (TVS), suspect ectopic pregnancy. * **Cervical Os:** In both threatened abortion and ectopic pregnancy, the internal os remains **closed**.

Q: Which of the following methods of treating eclampsia has the least effect on neonates?

Magnesium sulfate regimen. **Explanation:** The management of eclampsia focuses on controlling seizures while minimizing maternal and neonatal morbidity. **Magnesium sulfate ($MgSO_4$)** is the gold standard (drug of choice) because it is highly effective at preventing recurrent seizures without causing significant central nervous system (CNS) depression in the neonate. 1. **Why Magnesium Sulfate is Correct:** Unlike sedatives, $MgSO_4$ acts primarily at the neuromuscular junction and as an NMDA receptor antagonist. While it does cross the placenta, at therapeutic maternal levels, it does not cause significant respiratory depression or sedation in the newborn. In fact, it provides a **neuroprotective effect** for preterm neonates, reducing the risk of cerebral palsy. 2. **Why Other Options are Incorrect:** * **Diazepam:** This benzodiazepine crosses the placenta rapidly and has a long half-life. It causes "Floppy Infant Syndrome," characterized by neonatal respiratory depression, hypotonia, and impaired thermoregulation. * **Phenobarbitone:** This barbiturate causes prolonged neonatal CNS depression, leading to poor sucking reflexes and respiratory distress. * **Lytic Cocktail:** This combination (usually Chlorpromazine, Promethazine, and Pethidine) causes profound maternal and neonatal sedation and is now considered obsolete in modern obstetric practice. **Clinical Pearls for NEET-PG:** * **Pritchard Regimen:** The standard IM regimen for $MgSO_4$ (4g IV + 10g IM loading; 5g IM every 4 hours). * **Therapeutic Range:** 4–7 mEq/L. * **Toxicity Signs:** Loss of patellar reflex (earliest sign at 7–10 mEq/L), followed by respiratory depression (>12 mEq/L). * **Antidote:** 10 ml of 10% Calcium Gluconate IV (administered slowly).

Q: A patient with twin pregnancy presents for ultrasound at 26 weeks gestation. The ultrasound reveals a single placenta. The first twin has an amniotic fluid index (AFI) of 5 cm, a fetal weight of 700 grams, and an non-visible bladder. The second twin has an AFI of 16 cm and a fetal weight of 1200 grams. What is the most likely diagnosis?

Twin-to-twin transfusion syndrome. **Explanation:** The correct diagnosis is **Twin-to-Twin Transfusion Syndrome (TTTS)**. This condition occurs in **monochorionic** (single placenta) twin pregnancies due to unbalanced vascular anastomoses in the placenta, leading to a shunting of blood from one twin (donor) to the other (recipient). **Why Option D is correct:** The clinical presentation perfectly matches the **Quintero Staging** criteria for TTTS: * **Donor Twin (Twin 1):** Exhibits "stuck twin" features—oligohydramnios (AFI ≤ 5 cm), growth restriction (700g), and a non-visible bladder (indicative of Stage II TTTS due to decreased renal perfusion). * **Recipient Twin (Twin 2):** Exhibits polyhydramnios (AFI ≥ 8-10 cm or MVP > 8 cm) and macrosomia (1200g) due to volume overload and polyuria. **Why incorrect options are wrong:** * **Option A:** While the first twin does have growth restriction, the presence of a single placenta and the specific combination of **polyhydramnios-oligohydramnios sequence (TOPS)** makes TTTS the definitive diagnosis rather than isolated IUGR. * **Options B & C:** Twin Reversed Arterial Perfusion (TRAP) syndrome, also known as **Acardiac Twin**, involves a normal "pump" twin and a severely malformed twin without a functioning heart. In this case, both twins are structurally intact, though one is smaller and has an empty bladder. **High-Yield Clinical Pearls for NEET-PG:** * **Prerequisite:** TTTS only occurs in **Monochorionic** pregnancies. * **Diagnosis:** Based on ultrasound (Single placenta, same sex, and the Poly-Oli sequence). * **Quintero Staging:** Stage I (Poly/Oli), Stage II (Empty bladder in donor), Stage III (Abnormal Dopplers), Stage IV (Hydrops), Stage V (Death). * **Treatment of Choice:** Fetoscopic Laser Photocoagulation of placental anastomoses.

Q: All of the following adverse outcomes are associated with post-term pregnancy except?

Polyhydramnios. **Explanation:** Post-term pregnancy is defined as a pregnancy that extends to or beyond **42 weeks (294 days)** of gestation. The correct answer is **Polyhydramnios** because post-term pregnancy is actually associated with **Oligohydramnios** (decreased amniotic fluid) [1]. **1. Why Polyhydramnios is the Correct Answer (The Exception):** In post-term pregnancies, placental function begins to decline (placental insufficiency) [1]. This leads to decreased fetal renal perfusion, resulting in reduced fetal urine output—the primary source of amniotic fluid in late pregnancy. Therefore, **Oligohydramnios** is a hallmark complication, often leading to cord compression and fetal distress [1]. **2. Analysis of Incorrect Options (Associated Risks):** * **Stillbirth:** The risk of perinatal mortality increases significantly after 42 weeks due to uteroplacental insufficiency and "placental aging," which reduces oxygen and nutrient delivery to the fetus [1]. * **Shoulder Dystocia:** Continued fetal growth in utero often leads to **macrosomia** (birth weight >4000-4500g). This increases the risk of obstructed labor and shoulder dystocia during vaginal delivery [1]. * **Meconium Aspiration:** Post-term fetuses have more mature gastrointestinal tracts and are prone to episodes of hypoxia (due to cord compression from oligohydramnios). This triggers the passage of meconium into the amniotic fluid, which the fetus may aspirate [1]. **High-Yield NEET-PG Pearls:** * **Definition:** Post-term (≥42 weeks) vs. Late-term (41 weeks to 41 weeks 6 days). * **Most Common Cause:** Incorrect dating (inaccurate LMP). * **Dysmaturity Syndrome (Post-maturity Syndrome):** Seen in 20% of post-term neonates; characterized by loss of subcutaneous fat, wrinkled skin (parchment-like), and long nails [1]. * **Management:** Induction of labor is generally recommended between 41 and 42 weeks to prevent these complications.

Q: What is the best method for fetal monitoring or screening?

Manning score. **Explanation:** The **Manning score**, also known as the **Biophysical Profile (BPP)**, is considered the gold standard for fetal monitoring because it combines both acute and chronic markers of fetal well-being. By utilizing ultrasound to assess four parameters (fetal breathing movements, gross body movements, fetal tone, and amniotic fluid volume) alongside the Non-Stress Test (NST), it provides a comprehensive evaluation of the fetal central nervous system and placental function. This multi-parameter approach significantly reduces the rate of false-positive results compared to using any single test in isolation. **Analysis of Incorrect Options:** * **Bishop score:** This is used to assess **cervical ripeness** and predict the success of induction of labor; it is not a method for monitoring fetal well-being. * **Non-stress test (NST):** While a common screening tool, it only assesses the acute fetal heart rate response. It has a high false-positive rate and is less comprehensive than the Manning score, of which it is actually a component. * **Cardiff count 10 formula:** This is a method for **Daily Fetal Movement Count (DFMC)** performed by the mother. While useful for screening in low-risk pregnancies, it is subjective and less reliable than clinical biophysical monitoring. **Clinical Pearls for NEET-PG:** * **Manning Score Components:** Each of the 5 parameters is scored as 0 or 2. A score of **8-10 is normal**, while **4 or less indicates fetal distress** requiring urgent intervention. * **Modified BPP:** Consists of only the **NST** (acute marker) and **Amniotic Fluid Index** (chronic marker). It is often used as a faster alternative to the full Manning score. * **First sign to disappear:** In fetal hypoxia, fetal breathing movements are usually the first to be lost, while fetal tone is the last to disappear (indicating severe acidemia).

Q: In which type of placenta do the chorionic vessels separate before reaching the placental margin?

Velamentous placenta. **Explanation:** The correct answer is **Velamentous placenta**. In a **Velamentous insertion of the cord**, the umbilical cord inserts into the fetal membranes (amnion and chorion) rather than directly into the placental mass. Consequently, the umbilical/chorionic vessels must travel through the membranes, unprotected by Wharton’s jelly, before reaching the placental margin. This makes the vessels vulnerable to compression or rupture. **Analysis of Options:** * **Battledoor placenta (Marginal insertion):** The cord attaches at the very margin of the placenta rather than the center. However, the vessels do not travel through the membranes; they remain within the placental disc. * **Circumvallate placenta:** This is a morphological variation where the chorionic plate is smaller than the basal plate. It is characterized by a thickened, opaque ring (a double fold of amnion and chorion) at the periphery. The vessels do not separate in the membranes here. * **Placenta marginata:** A milder form of circumvallate placenta where the fetal membranes insert at the edge of the placental disc without the characteristic peripheral fold or shelf. **High-Yield Clinical Pearls for NEET-PG:** * **Vasa Previa:** If velamentous vessels cross the internal os ahead of the presenting part, it is called vasa previa. Rupture of these vessels (often during ROM) leads to painless vaginal bleeding and rapid fetal exsanguination (**Benckiser’s hemorrhage**). * **Diagnosis:** Velamentous insertion is best diagnosed using **Color Doppler Ultrasound**. * **Apt Test:** Used to differentiate fetal blood from maternal blood in cases of antepartum hemorrhage.

Question 1

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

Accepted Answer

Kleihauer Betke test

Answer

Apt test

Answer

Bubbling test

Answer

Liley test

Question 2

A 25-year-old G2P1 female has a history of previous preterm birth at 32 weeks. What is the percentage chance of preterm birth in this pregnancy?

Accepted Answer

15%

Answer

5%

Answer

10%

Answer

25%

Question 3

What is the key difference between ectopic pregnancy and threatened abortion?

Accepted Answer

Uterine size corresponds to gestational age

Answer

Presence of minimal vaginal bleeding

Answer

Pain typically follows bleeding

Answer

Manifests at an early gestational age

Question 4

Which of the following methods of treating eclampsia has the least effect on neonates?

Accepted Answer

Magnesium sulfate regimen

Answer

Lytic cocktail regimen

Answer

Diazepam therapy

Answer

Phenobarbitone therapy

Question 5

A patient with twin pregnancy presents for ultrasound at 26 weeks gestation. The ultrasound reveals a single placenta. The first twin has an amniotic fluid index (AFI) of 5 cm, a fetal weight of 700 grams, and an non-visible bladder. The second twin has an AFI of 16 cm and a fetal weight of 1200 grams. What is the most likely diagnosis?

Accepted Answer

Twin-to-twin transfusion syndrome

Answer

Intrauterine growth restriction (IUGR) of the first twin and normal growth of the second twin

Answer

Twin reverse arterial perfusion syndrome

Answer

Acardiac twin

Question 6

All of the following adverse outcomes are associated with post-term pregnancy except?

Accepted Answer

Polyhydramnios

Answer

Stillbirth

Answer

Shoulder dystocia

Answer

Meconium aspiration

Question 7

Abnormal baseline variability in a fetus is defined as:

Accepted Answer

Beat-to-beat variation less than 5 beats per minute for 90 minutes.

Answer

Beat-to-beat variation less than 5 beats per minute.

Answer

Beat-to-beat variation less than 5 beats per minute for 40 minutes.

Answer

Beat-to-beat variation less than 5 beats per minute for 60 minutes.

Question 8

What is the best method for fetal monitoring or screening?

Accepted Answer

Manning score

Answer

Bishop score

Answer

Non-stress test

Answer

Cardiff count 10 formula

Question 9

In which type of placenta do the chorionic vessels separate before reaching the placental margin?

Accepted Answer

Velamentous placenta

Answer

Battledoor placenta

Answer

Circumvallate placenta

Answer

Placenta marginata

Question 10

Fetal biophysical profile used for the assessment of fetal well-being does not include which of the following?

Accepted Answer

Contraction stress test

Answer

Fetal breathing movements

Answer

Fetal tone

Answer

Amniotic fluid volume

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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