Maternal-Fetal Medicine Practice Questions

Q: All of the following are associated with placental abruption, EXCEPT?

Hypotension. **Explanation:** Placental abruption (Abruptio Placentae) is the premature separation of a normally situated placenta from the uterine wall. The primary pathophysiology involves **vascular disruption** and **hypertension**, not hypotension. **Why Hypotension is the Correct Answer:** **Hypertension** (both chronic and pregnancy-induced) is the most significant risk factor for abruption. High blood pressure causes degenerative changes in the spiral arteries, leading to hemorrhage into the decidua basalis. **Hypotension** is a *consequence* of the resulting blood loss (hypovolemic shock) rather than a predisposing cause. **Analysis of Incorrect Options:** * **Cocaine abuse:** Cocaine is a potent vasoconstrictor that causes acute, severe maternal hypertension and uterine artery vasospasm, leading to placental shearing. * **Cigarette smoking:** Nicotine and carbon monoxide cause decidual hypoxemia and vascular necrosis. Smokers have a 2-fold increased risk of abruption. * **Pre-eclampsia:** This is the most common pathological condition associated with abruption. The underlying widespread endothelial dysfunction and vasospasm directly predispose the placenta to separation. **NEET-PG High-Yield Pearls:** * **Most common risk factor:** Previous history of abruption (recurrence risk is 5–15%). * **Most common "preventable" risk factor:** Maternal Hypertension. * **Clinical Triad:** Painful vaginal bleeding, uterine tenderness/rigidity (woody hard uterus), and fetal distress. * **Couvelaire Uterus:** A complication where retroplacental blood infiltrates the myometrium, appearing as a bluish-purple discoloration. * **Associated Complication:** Abruption is the most common cause of **DIC** (Disseminated Intravascular Coagulation) in pregnancy due to the release of thromboplastin into the maternal circulation.

Q: A 18-week pregnant multigravida, Rh-negative, with a previous child born with a chromosomal abnormality, underwent cordocentesis. Which test is used to differentiate between maternal and fetal blood in a given sample?

Apt test. **Explanation:** The correct answer is the **Apt test** (Alkali Denaturation Test). This test is specifically designed to differentiate between fetal and maternal blood based on the biochemical properties of hemoglobin. **1. Why the Apt test is correct:** Fetal hemoglobin (**HbF**) is resistant to denaturation by strong bases, whereas adult hemoglobin (**HbA**) is not. In this test, the blood sample is mixed with 1% sodium hydroxide (NaOH). If the blood is maternal (HbA), it denatures and turns **yellow-brown**. If the blood is fetal (HbF), it remains stable and stays **pink**. This is crucial during cordocentesis to ensure the sample obtained is truly fetal blood and not contaminated by maternal blood. **2. Why the other options are incorrect:** * **Kleihauer-Betke test:** This is used to **quantify** the amount of fetal-maternal hemorrhage (FMH) in the maternal circulation (e.g., to calculate the dose of Anti-D). It is an acid-elution test performed on a maternal blood smear, not a direct test to identify the source of a sample. * **Osmotic fragility test:** Used primarily to diagnose **Hereditary Spherocytosis** by measuring the resistance of RBCs to hemolysis in hypotonic solutions. * **Bubble stability test:** A bedside test used to assess **fetal lung maturity** by checking for the presence of surfactants in amniotic fluid. **Clinical Pearls for NEET-PG:** * **Apt Test Uses:** Differentiating fetal from maternal blood in cases of **Vasa Previa** (vaginal bleeding) or during **Cordocentesis**. * **Cordocentesis (PUBS):** Usually performed after 18 weeks; the most common site is the umbilical vein at the placental insertion. * **Kleihauer-Betke Formula:** Fetal cells counted / Total cells × 5000 = Volume of FMH (mL). This is a high-yield calculation for Rh-isoimmunization questions.

Q: In a patient receiving magnesium sulfate therapy, at what serum magnesium level does the patellar (knee) reflex typically disappear?

10-12 mEq/L. ### Explanation Magnesium sulfate ($MgSO_4$) is the drug of choice for seizure prophylaxis in pre-eclampsia and control in eclampsia. It acts as a CNS depressant and neuromuscular blocker. Because it is excreted almost entirely by the kidneys, toxicity is a significant risk, especially in patients with renal impairment. Monitoring clinical signs is vital because they disappear in a predictable, sequential order as serum levels rise. **1. Why Option B is Correct:** The **patellar reflex (knee jerk)** is the first clinical sign of magnesium toxicity. It typically disappears when serum magnesium levels reach **10–12 mEq/L** (or 8–10 mg/dL). This occurs because magnesium inhibits the release of acetylcholine at the neuromuscular junction, blocking the deep tendon reflex arc. **2. Analysis of Incorrect Options:** * **Option A (6–8 mEq/L):** This is the **therapeutic range** required for seizure prophylaxis. At this level, reflexes are present, and the patient is hemodynamically stable. * **Option C (12–14 mEq/L):** At these levels, **respiratory depression** and narcosis occur. This is a critical emergency requiring immediate intervention. * **Option D (>15 mEq/L):** Levels exceeding 15–20 mEq/L lead to **cardiac arrest** due to the direct effect of magnesium on the cardiac conduction system (heart block). **3. Clinical Pearls for NEET-PG:** * **Antidote:** 10 ml of 10% **Calcium Gluconate** IV (administered over 10 minutes). * **Monitoring Parameters:** Before every dose, check for: 1. Presence of patellar reflex (earliest sign of toxicity). 2. Respiratory rate >12–14/min. 3. Urine output >30 ml/hr (as magnesium is renally excreted). * **Therapeutic Level Conversion:** 4–7 mEq/L is approximately 4.8–8.4 mg/dL. Always check the units provided in the question.

Q: A 21-year-old woman with 8 weeks of amenorrhea presents in shock. What is the likely diagnosis?

Ruptured ectopic pregnancy. **Explanation:** The clinical presentation of a young woman with **amenorrhea (8 weeks)** and sudden **hypovolemic shock** is a classic "spotter" for a **Ruptured Ectopic Pregnancy**. In this condition, the gestational sac implants outside the uterine cavity (most commonly in the ampulla of the fallopian tube). As the embryo grows, it outstrips the distensibility of the tube, leading to rupture and massive intraperitoneal hemorrhage, which manifests as shock. **Analysis of Options:** * **Ruptured Ectopic Pregnancy (Correct):** This is the most common cause of life-threatening hemoperitoneum in the first trimester. The 8-week mark is a typical time for tubal rupture. * **Incarcerated Uterus:** This usually occurs between 12–16 weeks of gestation when a retroverted gravid uterus becomes trapped in the pelvic cavity. It presents with urinary retention, not sudden shock. * **Torsion of Ovarian Cyst:** While it causes acute pelvic pain, it rarely leads to hemodynamic collapse (shock) unless accompanied by rupture of a large hemorrhagic cyst or infarction leading to secondary sepsis. * **Threatened Abortion:** This presents with vaginal bleeding and mild cramping with a closed cervical os. It does not cause shock unless it progresses to an Incomplete Abortion with massive external hemorrhage. **NEET-PG High-Yield Pearls:** * **Most common site of Ectopic Pregnancy:** Fallopian tube (95%), specifically the **Ampulla**. * **Most common site for rupture:** Isthmus (6–8 weeks) due to its narrow lumen; Ampulla ruptures later (8–12 weeks). * **Gold Standard Diagnosis:** Laparoscopy. * **Classic Triad:** Amenorrhea, abdominal pain, and vaginal bleeding (present in only 50% of cases). * **Management of Shock:** Immediate aggressive fluid resuscitation and **emergency laparotomy** (salpingectomy) to control bleeding.

Question 1

Which of the following is NOT considered a pregnancy morbidity associated with Antiphospholipid Antibody Syndrome (APLAS)?

Accepted Answer

Three or more unexplained spontaneous abortions before the second trimester.

Answer

One or more fetal deaths at or beyond 10 weeks of gestation with a morphologically normal fetus.

Answer

One or more premature births before 34 weeks of gestation of a morphologically normal fetus due to eclampsia or pre-eclampsia.

Answer

Absence of any observed abnormalities.

Question 2

The below abnormality is seen in which type of pregnancy?

Accepted Answer

Monochorionic diamniotic twins

Answer

Dichorionic diamniotic twins

Answer

Monochorionic monoamniotic twins

Answer

Conjoined twins

Question 3

All of the following are associated with placental abruption, EXCEPT?

Accepted Answer

Hypotension

Answer

Cocaine abuse

Answer

Cigarette smoking

Answer

Pre-eclampsia

Question 4

A 30-year-old gravida 3 presents to the Gynaecology OPD with a 6-month history of amenorrhea, vaginal bleeding for 1 day, and significant pallor. Her ultrasound findings indicate a 28-week intrauterine fetal death with placental abruption. What is the best line of management?

Accepted Answer

Artificial rupture of membranes with Syntocinon drip and arrange for blood transfusion

Answer

Immediate cesarean section

Answer

Artificial rupture of membranes with oxytocin drip

Answer

Wait for spontaneous onset of labor

Question 5

Which one of the following regarding antenatal assessment of umbilical arteries by color Doppler study is TRUE?

Accepted Answer

The flow velocities and the S/D ratio are useful to evaluate high-risk pregnancies

Answer

There is decreased S/D ratio in smoker and nicotine abusing pregnant females

Answer

The reduced diastolic flow at term indicates good prognosis

Answer

In otherwise normal pregnancies, the increased S/D ratio is normal in smoking females

Question 6

A 18-week pregnant multigravida, Rh-negative, with a previous child born with a chromosomal abnormality, underwent cordocentesis. Which test is used to differentiate between maternal and fetal blood in a given sample?

Accepted Answer

Apt test

Answer

Kleihauer-Betke test

Answer

Osmotic fragility test

Answer

Bubble stability test

Question 7

Regarding trophoblast invasion of maternal spiral arteries, all are true except?

Accepted Answer

Invasion by trophoblasts involves both decidual spiral arteries and decidual veins.

Answer

First wave occurs before 12 weeks and consists of invasion up to the border between decidua and myometrium.

Answer

Second wave occurs between 12 and 16 weeks with invasion of intramyometrial segments of spiral arteries.

Answer

Narrow lumen, muscular spiral arteries are converted into dilated, low resistance vessels.

Question 8

In a patient receiving magnesium sulfate therapy, at what serum magnesium level does the patellar (knee) reflex typically disappear?

Accepted Answer

10-12 mEq/L

Answer

6-8 mEq/L

Answer

12-14 mEq/L

Answer

Greater than 15 mEq/L

Question 9

Which of the following is true about chorionic villi biopsy?

Accepted Answer

Rh immunoglobulin prophylaxis is not necessary

Answer

Strongly associated with fetal limb defects

Answer

Done between 10-12 weeks of gestation

Answer

Done to diagnose genetic disorders

Question 10

A 21-year-old woman with 8 weeks of amenorrhea presents in shock. What is the likely diagnosis?

Accepted Answer

Ruptured ectopic pregnancy

Answer

Incarcerated amnion

Answer

Torsion of ovarian cyst

Answer

Threatened abortion

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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