Maternal-Fetal Medicine Practice Questions

Q: What is the best test to quantify feto-maternal hemorrhage in Rh isoimmunization?

Kleinhauser test. ### Explanation **Correct Answer: C. Kleinhauser test (Kleihauer-Betke Test)** The **Kleihauer-Betke (KB) test** is the gold standard for **quantifying** the volume of feto-maternal 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 and stained, adult cells appear as "ghost cells" (pale), while fetal red cells remain dark and intact. By counting the percentage of fetal cells, the volume of FMH is calculated to determine the required dose of Anti-D immunoglobulin. **Analysis of Incorrect Options:** * **A. Leukocyte Poor Platelet (LPT):** This is a blood product used to prevent febrile non-hemolytic transfusion reactions; it has no role in diagnosing or quantifying FMH. * **B. Direct Coombs Test (DCT):** This test detects antibodies already bound to the surface of red blood cells. In Rh isoimmunization, a positive DCT on **fetal/neonatal cord blood** confirms that maternal antibodies have crossed the placenta and coated fetal RBCs. It does not quantify the hemorrhage. * **D. Indirect Coombs Test (ICT):** This is a **screening** test used to detect unbound Rh antibodies in the **maternal serum**. While it confirms sensitization, it cannot quantify the volume of the bleed. **High-Yield Clinical Pearls for NEET-PG:** * **Screening vs. Quantification:** The **Rosette Test** is the initial qualitative screening test for FMH. If positive, the **KB test** is performed to quantify the bleed. * **Calculation Formula:** Volume of FMH (mL) = (% of fetal cells × 50). * **Anti-D Dosing:** 300 mcg of Anti-D neutralizes 30 mL of fetal whole blood (or 15 mL of fetal packed RBCs). * **Timing:** Anti-D should ideally be given within **72 hours** of the sensitizing event.

Q: In which of the following conditions, the medical treatment of ectopic pregnancy is contraindicated?

Presence of fetal heart activity. **Explanation:** Medical management of ectopic pregnancy, primarily using **Methotrexate (MTX)**, is reserved for hemodynamically stable patients who meet specific criteria. The presence of **fetal heart activity (Option C)** is a major contraindication because it indicates a high trophoblastic load and a more advanced pregnancy, which significantly increases the risk of treatment failure and tubal rupture. **Analysis of Options:** * **Presence of fetal heart activity (Correct):** This is an absolute contraindication for medical management. MTX is less effective when there is active cardiac motion, necessitating surgical intervention. * **Sac size is 3 cm (Incorrect):** Medical management is generally indicated if the gestational sac diameter is **< 3.5 cm or 4 cm**. A 3 cm sac falls within the acceptable range for MTX. * **Blood in pelvis is 70 mL (Incorrect):** While significant hemoperitoneum (suggesting rupture) is a contraindication, a small amount of free fluid (usually **< 100 mL**) in the pouch of Douglas is common and does not preclude medical treatment. * **Previous ectopic pregnancy (Incorrect):** A history of ectopic pregnancy is not a contraindication. In fact, medical management is often preferred in these cases to avoid further surgical scarring of the fallopian tubes. **NEET-PG High-Yield Pearls:** * **Ideal Candidate for MTX:** Hemodynamically stable, Serum β-hCG < 5000 mIU/mL, Sac size < 3.5 cm, and No fetal cardiac activity. * **Absolute Contraindications:** Ruptured ectopic pregnancy, hemodynamic instability, breastfeeding, immunodeficiency, and significant renal/hepatic/pulmonary disease. * **Dosing:** Most common is the single-dose regimen (50 mg/m² IM). * **Monitoring:** β-hCG levels are measured on Day 4 and Day 7. A drop of **≥ 15%** between Day 4 and 7 indicates successful treatment.

Q: What is the most common type of twins following assisted reproductive technology?

Dizygotic twins. **Explanation:** The correct answer is **Dizygotic twins (C)**. **Why Dizygotic twins is correct:** Assisted Reproductive Technology (ART), specifically ovulation induction and In-Vitro Fertilization (IVF), significantly increases the rate of multiple gestations. The primary mechanism is the **transfer of multiple embryos** into the uterus during IVF or the **stimulation of multiple follicles** during ovulation induction (using drugs like Clomiphene citrate or Gonadotropins). Since these twins arise from two separate ova fertilized by two separate sperm, they are dizygotic (fraternal). While ART also slightly increases the risk of monozygotic twinning compared to natural conception, dizygotic twins remain overwhelmingly more common in this population. **Why the other options are incorrect:** * **Monozygotic twins (A):** These occur from the splitting of a single fertilized ovum. While the incidence is higher in IVF (approx. 2–5%) compared to natural conception (0.4%), they are still far less frequent than dizygotic twins in ART. * **Acardiac twin (B):** This is a rare, severe complication of Monochorionic Diamniotic (MCDA) twins known as Twin Reversed Arterial Perfusion (TRAP) sequence. It is a specific pathology, not a "type" of twinning common to ART. * **Conjoined twins (D):** These are a rare complication of monozygotic twinning where the embryo divides very late (after day 13). They are extremely rare and not the standard outcome of ART. **High-Yield Clinical Pearls for NEET-PG:** * **Natural Twinning Rate:** Approximately 1 in 80 pregnancies (Hellin’s Law). * **Most common type of Monozygotic twins:** Monochorionic Diamniotic (MCDA) — division occurs at 4–8 days (Blastocyst stage). * **Vanishing Twin Syndrome:** Frequent in ART, where one twin is resorbed in the first trimester. * **Risk Factor:** The single most important risk factor for dizygotic twinning is the use of ovulation-inducing drugs.

Q: A large placenta is seen in which of the following conditions?

Twins. **Explanation:** The size and weight of the placenta are critical indicators of fetal well-being. A **large placenta (placentomegaly)** is generally defined as a placental thickness >4 cm or a weight exceeding the 90th percentile for gestational age. **1. Why "Twins" is correct:** In multiple pregnancies, the placenta must support more than one fetus. Whether it is a single large monochorionic placenta or two fused/separate dichorionic placentas, the total placental mass and surface area are significantly increased to meet the combined metabolic and nutritional demands of the fetuses. **2. Why the other options are incorrect:** * **Oligohydramnios:** This is often associated with placental insufficiency or renal anomalies. Reduced placental perfusion leads to a smaller, rather than larger, placenta. * **Intrauterine Growth Restriction (IUGR):** Most cases of "true" IUGR are caused by placental insufficiency (maternal vascular malperfusion). This results in a small, fibrotic, or infarcted placenta. * **Pre-eclamptic Toxemia (PET):** PET is characterized by failed trophoblastic invasion of spiral arteries, leading to chronic ischemia. This typically results in a small, thin placenta with multiple infarcts. **High-Yield Clinical Pearls for NEET-PG:** * **Causes of Large Placenta (Mnemonic: "D-H-I-T"):** * **D**iabetes Mellitus (Maternal) * **H**ydrops Fetalis (Immune and Non-immune) * **I**nfections (Syphilis, CMV, Toxoplasmosis) * **T**wins/Multiple Gestation * **Normal Placental Weight:** Approximately 1/6th of the baby's weight at term (approx. 500g). * **Syphilis:** Classically produces the largest placenta relative to fetal weight (often pale and greasy). * **Placentomegaly on Ultrasound:** Defined as a thickness >40 mm before 40 weeks.

Q: All the conditions mentioned below are associated with decreased fetal heart rate except?

Fetal movement. **Explanation:** The fetal heart rate (FHR) is a dynamic indicator of fetal well-being, regulated by the autonomic nervous system. To answer this question, one must distinguish between factors that cause **accelerations** versus those that cause **decelerations** or bradycardia. **1. Why Fetal Movement is the Correct Answer:** Fetal movement is associated with a **transient increase** in fetal heart rate, known as an **acceleration**. An acceleration is defined as a rise in FHR of at least 15 beats per minute (bpm) above the baseline, lasting for at least 15 seconds. This is a reassuring sign indicating a functional fetal sympathetic nervous system and the absence of acidemia. Therefore, it does not decrease the heart rate. **2. Analysis of Incorrect Options:** * **Chronic Hypoxia (B):** Prolonged oxygen deprivation leads to myocardial depression and increased vagal tone, resulting in a decrease in baseline FHR or late decelerations. * **Cord Compression (C):** This causes umbilical vein/artery occlusion, triggering a baroreceptor-mediated reflex that results in **variable decelerations** (abrupt decreases in FHR). * **Head Compression (D):** During labor, pressure on the fetal head increases intracranial pressure, stimulating the vagus nerve. This results in **early decelerations**, which are symmetrical decreases in FHR mirroring uterine contractions. **NEET-PG High-Yield Pearls:** * **Reactive Non-Stress Test (NST):** Defined by $\geq$ 2 accelerations in 20 minutes. * **Early Decelerations:** "Mirror images" of contractions; caused by head compression (vagal reflex); clinically benign. * **Late Decelerations:** Occur after the peak of contraction; caused by **uteroplacental insufficiency**; always pathological. * **Variable Decelerations:** Most common type; caused by **cord compression**; managed by changing maternal position.

Q: Macrosomia is defined as a fetal weight greater than which of the following?

4.5 kg. **Explanation:** **Fetal Macrosomia** is defined by the American College of Obstetricians and Gynecologists (ACOG) as a birth weight of **more than 4,500 grams (4.5 kg)**, regardless of gestational age. This threshold is chosen because the risks of maternal and neonatal morbidity (such as shoulder dystocia and birth trauma) increase significantly above this weight. * **Option D (4.5 kg) is Correct:** While some older texts used 4 kg as a cutoff, current clinical guidelines (ACOG) strictly define macrosomia as >4.5 kg. In clinical practice, a weight >4 kg is often termed "Large for Gestational Age" (LGA), but "Macrosomia" is the specific diagnosis for the 4.5 kg threshold. * **Options A & B (3 kg and 3.5 kg):** These represent normal average birth weights. The average birth weight for a term neonate is approximately 3.2 kg to 3.5 kg. * **Option C (4 kg):** This is the threshold for LGA (weight >90th percentile for gestational age). While often used interchangeably in casual clinical settings, it is not the formal definition of macrosomia for boards. **High-Yield Clinical Pearls for NEET-PG:** * **Most Common Cause:** Maternal Diabetes Mellitus (Gestational or Pre-gestational). * **Complications:** Shoulder dystocia (most feared), Erb’s palsy, postpartum hemorrhage (due to uterine atony), and perineal tears. * **Management:** Elective Cesarean Section is recommended if the estimated fetal weight is **>5 kg** in non-diabetic women or **>4.5 kg** in diabetic women. * **Ponderal Index:** Used to differentiate between symmetrical and asymmetrical growth; macrosomic infants of diabetic mothers often show asymmetrical growth (increased fat deposition on shoulders/abdomen).

Q: What is the appearance of the RBCs on the peripheral smear in physiological anemia of pregnancy?

Normocytic and Normochromic. ### Explanation **Correct Answer: C. Normocytic and Normochromic** **Why it is correct:** Physiological anemia of pregnancy is a **dilutional anemia**. During pregnancy, the plasma volume increases significantly (approx. 40–50%), while the red cell mass increases to a lesser extent (approx. 20–30%). This disproportionate rise leads to hemodilution, resulting in a lower hemoglobin concentration and hematocrit. However, the morphology of the individual red blood cells remains unaffected. Because the RBCs themselves are healthy and contain a normal amount of hemoglobin, they appear **Normocytic** (normal size/MCV) and **Normochromic** (normal color/MCHC) on a peripheral smear. **Why the other options are incorrect:** * **A & D (Microcytic):** Microcytic cells (low MCV) are characteristic of **Iron Deficiency Anemia (IDA)**, which is the most common *pathological* anemia in pregnancy. In IDA, cells are typically hypochromic as well. * **B (Macrocytic):** Macrocytic cells (high MCV) are seen in **Megaloblastic Anemia**, usually due to Folic Acid or Vitamin B12 deficiency. While common in pregnancy, this is a pathological state, not physiological. **High-Yield Clinical Pearls for NEET-PG:** * **Peak Hemodilution:** Occurs between **28–32 weeks** of gestation. * **WHO Definition:** Anemia in pregnancy is defined as **Hb < 11 g/dL**. * **ICMR/National Guidelines (India):** Anemia is defined as **Hb < 11 g/dL**; severe anemia is **< 7 g/dL**. * **Purpose:** Physiological anemia reduces blood viscosity, improving placental perfusion and protecting the mother against blood loss during delivery. * **MCV/MCHC:** These indices remain **stable** in physiological anemia; any deviation suggests a nutritional deficiency.

Question 1

What is the best test to quantify feto-maternal hemorrhage in Rh isoimmunization?

Accepted Answer

Kleinhauser test

Answer

Leukocyte Poor Platelet (LPT)

Answer

Direct Coombs Test (DCT)

Answer

Indirect Coombs Test

Question 2

In which of the following conditions, the medical treatment of ectopic pregnancy is contraindicated?

Accepted Answer

Presence of fetal heart activity

Answer

Sac size is 3 cm

Answer

Blood in pelvis is 70 mL

Answer

Previous ectopic pregnancy

Question 3

At 29 weeks gestational age, it becomes apparent that the fetus has developed hydrops. All of the following are characteristics of fetal hydrops except?

Accepted Answer

Small placenta

Answer

Polyhydramnios

Answer

Pericardial effusion

Answer

Subcutaneous edema

Question 4

What is the most common type of twins following assisted reproductive technology?

Accepted Answer

Dizygotic twins

Answer

Monozygotic twins

Answer

Acardiac twin

Answer

Conjoined twins

Question 5

A large placenta is seen in which of the following conditions?

Accepted Answer

Twins

Answer

Oligohydramnios

Answer

Intrauterine Growth Restriction (IUGR)

Answer

Pre-eclamptic toxemia

Question 6

Fetal growth restriction is defined as estimated fetal weight is below the ______ for their gestational age?

Accepted Answer

10th percentile

Answer

3rd percentile

Answer

5th percentile

Answer

15th percentile

Question 7

All the conditions mentioned below are associated with decreased fetal heart rate except?

Accepted Answer

Fetal movement

Answer

Chronic hypoxia

Answer

Cord compression

Answer

Head compression

Question 8

Macrosomia is defined as a fetal weight greater than which of the following?

Accepted Answer

4.5 kg

Answer

3 kg

Answer

3.5 kg

Answer

4 kg

Question 9

What is the appearance of the RBCs on the peripheral smear in physiological anemia of pregnancy?

Accepted Answer

Normocytic and Normochromic

Answer

Microcytic and Hypochromic

Answer

Macrocytic and Hyperchromic

Answer

Microcytic and Normochromic

Question 10

Which of the following steps are useful in the perinatal prevention of mother-to-child transmission?

Accepted Answer

All of these

Answer

Elective Cesarean section

Answer

Avoidance of breastfeeding

Answer

Antiretroviral therapy prophylaxis

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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