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: 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: What is the cut-off value of cervical length at 24 weeks of gestation for the prediction of preterm delivery?

2.5 cm. **Explanation:** The measurement of cervical length via **Transvaginal Ultrasound (TVS)** is a gold-standard screening tool for predicting spontaneous preterm birth (PTB). In clinical practice and according to standard guidelines (ACOG/RCOG), a cervical length of **<25 mm (2.5 cm)** before 24 weeks of gestation is the universally accepted threshold for identifying women at high risk for preterm delivery. **Why 2.5 cm is correct:** At 20–24 weeks, the average cervical length is approximately 35–40 mm. The 2.5 cm cut-off represents the **10th percentile** for the population. A cervix shorter than this indicates "cervical insufficiency" or premature ripening, significantly increasing the risk of delivery before 34 weeks. **Analysis of Incorrect Options:** * **0.5 cm (A):** This represents an extremely short or "effaced" cervix, indicating an imminent risk of delivery rather than a screening threshold. * **1.5 cm (B):** While this is the **5th percentile** and indicates a much higher risk, it is not the standard screening cut-off used to initiate primary interventions like progesterone. * **3.5 cm (D):** This is considered a normal, healthy cervical length at 24 weeks and carries a very high negative predictive value for preterm birth. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** TVS is superior to transabdominal ultrasound or digital examination for measuring cervical length. * **Management:** If cervical length is <2.5 cm in a singleton pregnancy, the treatment of choice is **Vaginal Progesterone**. * **Funneling:** The presence of "funneling" (opening of the internal os) often precedes cervical shortening and is a significant warning sign. * **Cervical Cerclage:** Indicated in patients with a history of prior spontaneous PTB and a current short cervix (<2.5 cm) before 24 weeks.

Q: Which intrauterine infections are most commonly associated with neural tube defects?

Toxoplasma gondii and Rubella virus. **Explanation:** The development of the neural tube occurs very early in embryogenesis (completed by the 28th day after conception). While most neural tube defects (NTDs) are multifactorial or linked to folic acid deficiency, certain intrauterine infections—specifically **Toxoplasma gondii** and **Rubella virus**—are recognized as significant infectious risk factors. **1. Why the Correct Answer is Right:** * **Toxoplasma gondii:** This parasite can interfere with early neuroepithelial proliferation. While it is classically known for the triad of chorioretinitis, hydrocephalus, and intracranial calcifications, early first-trimester infection is strongly associated with severe CNS dysgenesis, including anencephaly and myelomeningocele. * **Rubella virus:** The Congenital Rubella Syndrome (CRS) is highly teratogenic during the period of organogenesis. It causes mitotic arrest and angiopathy, which can disrupt the closure of the neural tube, leading to defects alongside its classic presentation of cataracts, PDA, and sensorineural deafness. **2. Why Other Options are Incorrect:** * **Cytomegalovirus (CMV):** While CMV is the most common congenital infection, it typically causes destructive lesions (microcephaly, periventricular calcifications) rather than primary induction defects like NTDs. * **Herpes Simplex Virus (HSV):** Congenital HSV is rare; most neonatal HSV is acquired during delivery. It typically presents with skin-eye-mouth (SEM) lesions or encephalitis rather than structural NTDs. **Clinical Pearls for NEET-PG:** * **Highest Risk Period:** The risk of structural malformations (like NTDs) is highest when the infection occurs in the **first trimester**. * **Prevention:** Periconceptional **Folic Acid (400 mcg/day)** is the most effective way to reduce NTD incidence by 70%. * **Screening:** Maternal **alpha-fetoprotein (MSAFP)** is elevated in open NTDs (Anencephaly/Spina bifida cystica).

Q: Which of the following is not associated with chorioamnionitis?

Placenta accreta. **Explanation:** **Chorioamnionitis** (Triple I: Intrauterine Inflammation or Infection) is an acute inflammation of the fetal membranes and amniotic fluid, typically caused by ascending polymicrobial infection. **Why Placenta Accreta is the correct answer:** Placenta accreta is a **structural/anatomical abnormality** where the chorionic villi adhere directly to the myometrium due to a defect in the decidua basalis (Nitabuch’s layer). It is primarily associated with previous uterine surgery (C-sections, D&C) and placenta previa. It is **not** an infectious or inflammatory process and therefore has no causal link with chorioamnionitis. **Analysis of incorrect options:** * **Preterm Labour (A):** Infection is a leading cause of preterm labor. Bacteria release phospholipase A2, which triggers prostaglandin synthesis, leading to cervical ripening and uterine contractions. * **Endometritis (B):** Chorioamnionitis is a significant risk factor for postpartum endometritis. The bacteria present in the amniotic cavity during labor persist and invade the uterine lining after delivery. * **Abruptio Placentae (C):** Inflammation of the decidua and membranes can lead to vascular fragility and retroplacental hemorrhage. There is a well-documented bidirectional relationship where infection can trigger abruption, and chronic abruption can predispose to infection. **NEET-PG High-Yield Pearls:** * **Gold Standard Diagnosis:** Histopathological examination of the placenta/membranes. * **Clinical Diagnosis (Gibbs Criteria):** Maternal fever (>38°C) plus two of: Maternal tachycardia, fetal tachycardia, uterine tenderness, or foul-smelling liquor. * **Management:** Prompt initiation of IV antibiotics (Ampicillin + Gentamicin) and **delivery** (not necessarily C-section; vaginal delivery is preferred unless contraindicated). * **Most common organism:** *Ureaplasma urealyticum* and *Mycoplasma hominis*.

Q: A 25-week pregnant patient presents with severe left calf pain and swelling. The affected area is slightly edematous, with no erythema. A positive Homan sign is noted, raising concern for deep vein thrombosis. Which diagnostic modality should be ordered?

Real-time ultrasonography. **Explanation:** The clinical presentation of unilateral calf pain, swelling, and a positive Homan sign in a pregnant patient is highly suggestive of **Deep Vein Thrombosis (DVT)**. Pregnancy is a hypercoagulable state, increasing the risk of venous thromboembolism (VTE) by 4 to 5-fold. **Why Real-time Ultrasonography is correct:** Compression **Duplex Ultrasonography** (Real-time B-mode imaging combined with color Doppler) is the **first-line diagnostic modality** for suspected DVT in pregnancy. It is non-invasive, lacks ionizing radiation (making it safe for the fetus), and has high sensitivity and specificity (over 95%) for detecting proximal DVT. The primary diagnostic criterion is the **non-compressibility** of the vein under the ultrasound probe. **Why other options are incorrect:** * **MRI (Option A):** While accurate for diagnosing pelvic vein thrombosis, it is expensive, not readily available, and not the initial investigation of choice. * **Computed Tomographic Scanning (Option B):** CT involves significant ionizing radiation exposure to the fetus and requires intravenous contrast, which is generally avoided in pregnancy unless pulmonary embolism is suspected and other tests are inconclusive. * **Venography (Option C):** Once the "gold standard," it is now rarely used because it is invasive, technically difficult, and involves significant fetal radiation exposure. **Clinical Pearls for NEET-PG:** * **Left-sided Predominance:** 80-90% of pregnancy-related DVTs occur in the **left leg** due to "May-Thurner Syndrome" (compression of the left common iliac vein by the right common iliac artery). * **D-dimer:** Its utility is limited in pregnancy because D-dimer levels naturally increase with gestational age, leading to low specificity. * **Treatment:** Low Molecular Weight Heparin (LMWH) is the drug of choice. **Warfarin is contraindicated** due to teratogenicity (except in specific cases like mechanical heart valves).

Q: What is the most important factor affecting the outcome of twin gestation?

Chorionicity. **Explanation:** In twin gestations, **chorionicity** (the number of placentas) is the single most important factor determining both maternal and fetal prognosis. Monochorionic (MC) twins carry significantly higher risks compared to dichorionic (DC) twins due to the presence of vascular anastomoses on the placental surface. These connections can lead to unique, life-threatening complications such as **Twin-to-Twin Transfusion Syndrome (TTTS)**, Twin Anemia-Polycythemia Sequence (TAPS), and Twin Reversed Arterial Perfusion (TRAP) sequence. Additionally, MC twins have higher rates of congenital anomalies, intrauterine growth restriction (IUGR), and fetal demise. **Analysis of Options:** * **Lie of the first/second twin (A & B):** While the presentation (e.g., vertex vs. non-vertex) is crucial for determining the **mode of delivery** (vaginal vs. cesarean), it does not dictate the overall pregnancy outcome or the risk of antenatal complications. * **Placental position (D):** While a low-lying placenta (placenta previa) can cause antepartum hemorrhage, it is a general obstetric complication and not the primary driver of twin-specific morbidity. **High-Yield Clinical Pearls for NEET-PG:** * **Lambda Sign (Twin Peak Sign):** Diagnostic of **Dichorionic** twins on ultrasound (seen at the membrane-placenta junction). * **T-Sign:** Diagnostic of **Monochorionic** twins (thin membrane meeting the placenta at a 90-degree angle). * **Optimal Timing for Chorionicity:** Best determined by ultrasound in the first trimester (**10–14 weeks**). * **Perinatal Mortality:** Is 3–4 times higher in monochorionic twins compared to dichorionic twins.

Question 1

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

Accepted Answer

Hypotension

Answer

Cocaine abuse

Answer

Cigarette smoking

Answer

Pre-eclampsia

Question 2

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 3

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 4

In peripartum cardiomyopathy, cardiac failure can develop anytime during which period?

Accepted Answer

The last month of pregnancy or within 5 months after delivery

Answer

The antenatal period

Answer

The third trimester

Answer

The first 6 weeks postpartum

Question 5

What is the cut-off value of cervical length at 24 weeks of gestation for the prediction of preterm delivery?

Accepted Answer

2.5 cm

Answer

0.5 cm

Answer

1.5 cm

Answer

3.5 cm

Question 6

Which intrauterine infections are most commonly associated with neural tube defects?

Accepted Answer

Toxoplasma gondii and Rubella virus

Answer

Cytomegalovirus (CMV) and Toxoplasma gondii

Answer

Rubella virus and Herpes simplex virus

Answer

Cytomegalovirus (CMV) and Herpes simplex virus

Question 7

Which of the following is not associated with chorioamnionitis?

Accepted Answer

Placenta accreta

Answer

Preterm labour

Answer

Endometritis

Answer

Abruptio placentae

Question 8

A 25-week pregnant patient presents with severe left calf pain and swelling. The affected area is slightly edematous, with no erythema. A positive Homan sign is noted, raising concern for deep vein thrombosis. Which diagnostic modality should be ordered?

Accepted Answer

Real-time ultrasonography

Answer

MRI

Answer

Computed tomographic scanning

Answer

Venography

Question 9

What is the recommended advice for an HIV-positive primigravida near term?

Accepted Answer

Treatment should be initiated before labor.

Answer

Avoid mixing of blood during labor.

Answer

Vaginal delivery is preferred.

Answer

Cesarean section would decrease transmission of HIV to the baby.

Question 10

What is the most important factor affecting the outcome of twin gestation?

Accepted Answer

Chorionicity

Answer

Lie of the first twin

Answer

Lie of the second twin

Answer

Placental position

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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