Maternal-Fetal Medicine Practice Questions

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.

Q: All of the following are increased in infants of mothers with heart disease, except:

Neural tube defect. **Explanation:** Maternal heart disease significantly impacts fetal outcomes primarily through two mechanisms: **chronic fetal hypoxia** and **genetic predisposition**. **Why Neural Tube Defects (NTD) is the correct answer:** Neural tube defects are primarily associated with folic acid deficiency, maternal diabetes, or exposure to teratogens (like valproate). There is no direct pathophysiological link between maternal cardiac disease and the failure of neural tube closure. Therefore, the incidence of NTDs remains the same as in the general population. **Analysis of Incorrect Options:** * **Prematurity:** Mothers with significant heart disease (especially those with cyanosis or congestive heart failure) have a higher incidence of preterm labor, often due to chronic hypoxia or iatrogenic delivery necessitated by deteriorating maternal health. * **Intrauterine Growth Restriction (IUGR):** Chronic maternal hypoxia and reduced cardiac output lead to placental insufficiency. This results in a suboptimal supply of oxygen and nutrients to the fetus, leading to symmetrical or asymmetrical growth restriction. * **Increased Incidence of Cardiac Disease:** Congenital heart disease (CHD) has a polygenic inheritance pattern. If a mother has CHD, the risk of the fetus having a cardiac defect increases from the baseline 0.8% to approximately 3–5% (depending on the specific lesion). **NEET-PG High-Yield Pearls:** * **Most common heart disease in pregnancy (India):** Rheumatic Heart Disease (Mitral Stenosis is the most common lesion). * **Most common heart disease in pregnancy (Developed countries):** Congenital Heart Disease. * **Highest risk period:** The immediate postpartum period (first 24–48 hours) due to the sudden "autotransfusion" of blood from the involuting uterus into the systemic circulation. * **Predictor of Fetal Risk:** Maternal cyanosis (Oxygen saturation <85%) is the strongest predictor of poor fetal outcome.

Q: All of the following diseases are transmitted vertically in the 3rd trimester of pregnancy except?

Congenital parvovirus B19. **Explanation:** The core concept tested here is the **timing of vertical transmission** and the resulting fetal pathology. While many infections can occur at any stage, their peak incidence of transmission often varies by trimester. **Why Parvovirus B19 is the correct answer:** Parvovirus B19 specifically targets **erythroid progenitor cells** in the fetal bone marrow and liver. The peak period of fetal vulnerability and vertical transmission is the **second trimester** (specifically 13–24 weeks), as this is the period of maximal hepatic hematopoiesis. Infection during this window leads to severe fetal anemia, high-output cardiac failure, and **Hydrops Fetalis**. While transmission can occur later, it is classically associated with second-trimester complications rather than third-trimester transmission. **Analysis of Incorrect Options:** * **Congenital Syphilis:** Transmission can occur at any stage, but the risk **increases with gestational age**, reaching its peak in the third trimester. * **Congenital Toxoplasmosis:** There is an inverse relationship between severity and transmission. While first-trimester infection is more severe, the **highest rate of transmission (up to 60-80%)** occurs in the third trimester. * **Congenital Hepatitis B:** Vertical transmission (primarily peripartum) is most common if the mother acquires the infection in the **third trimester** (up to 90% risk) compared to the first trimester (only 10%). **NEET-PG High-Yield Pearls:** * **Toxoplasmosis:** Transmission risk is highest in the 3rd trimester; Severity is highest in the 1st trimester. * **Parvovirus B19:** Most common cause of non-immune hydrops fetalis; diagnosed via MCA-PSV doppler (looking for fetal anemia). * **Syphilis:** Langhans layer of the placenta prevents transmission before 16 weeks; hence, treating the mother before 16 weeks prevents congenital syphilis.

Question 1

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 2

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 3

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 4

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 5

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 6

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

Question 7

All of the following are increased in infants of mothers with heart disease, except:

Accepted Answer

Neural tube defect

Answer

Prematurity

Answer

Intrauterine growth restriction (IUGR)

Answer

Increased incidence of cardiac disease

Question 8

All of the following diseases are transmitted vertically in the 3rd trimester of pregnancy except?

Accepted Answer

Congenital parvovirus B19

Answer

Congenital syphilis

Answer

Congenital toxoplasmosis

Answer

Congenital hepatitis B

Question 9

What is the most common cause of epilepsy in pregnancy?

Accepted Answer

Idiopathic

Answer

Tuberculous meningitis

Answer

Cerebral malaria

Answer

Brain tumor

Question 10

Rh incompatibility does not produce serious complications in the first pregnancy. Which of the following explains this phenomenon?

Accepted Answer

Antibodies are not able to cross the placenta.

Answer

Antibody titer is very low during secondary immune response.

Answer

IgG generated is ineffective against fetal red cells.

Answer

Massive hemolysis is compensated by increased erythropoiesis.

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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