Maternal-Fetal Medicine — MCQs

A 24-year-old woman at 8 weeks of gestation presents with a history of pulmonary embolism 7 years ago during her first pregnancy. She was treated with intravenous heparin followed by several months of oral warfarin and has had no further evidence of thromboembolic disease for over 6 years. Which of the following statements about her current condition is true?

Q848Medium

Which of the following situations poses the greatest risk of Rh incompatibility?

Q849Easy

Maternal near miss refers to:

Q850Easy

What is the best method for diagnosing the degree of placenta previa?

Maternal-Fetal Medicine Indian Medical PG Practice Questions and MCQs

Question 841: Which measurement correlates with the suboccipitobregmatic diameter of the fetal skull?

A. 9.4 cm
B. 10 cm (Correct Answer)
C. 11.3 cm
D. 12 cm

Explanation: The **Suboccipitobregmatic (SOB) diameter** is the most important diameter of the fetal skull in clinical obstetrics, as it is the presenting diameter in a well-flexed vertex presentation. ### 1. Why the Correct Answer is Right The **Suboccipitobregmatic diameter** extends from the undersurface of the occiput (at the junction of the neck) to the center of the anterior fontanelle (bregma). Its measurement is **9.5 cm**. In the context of NEET-PG and standard textbooks like Williams Obstetrics or Dutta’s Textbook of Obstetrics, while the precise measurement is 9.5 cm, **10 cm** is the closest clinical approximation provided in the options. It represents the smallest possible diameter, allowing for the easiest passage through the birth canal. ### 2. Analysis of Incorrect Options * **A. 9.4 cm:** While very close to 9.5 cm, standard medical entrance exams traditionally pair the SOB diameter with the 9.5–10 cm range. * **C. 11.3 cm:** This correlates with the **Suboccipitofrontal (SOF)** diameter (10 cm) or the **Occipitofrontal (OF)** diameter (11.5 cm), which is the presenting diameter in a deflexed vertex (military) position. * **D. 12 cm:** This correlates with the **Submentobregmatic (SMB)** diameter (9.5 cm) or the **Mentovertical (MV)** diameter, which is the largest diameter (13.5 cm) seen in brow presentations. ### 3. High-Yield Clinical Pearls for NEET-PG * **Smallest Diameter:** Suboccipitobregmatic (9.5 cm) – seen in complete flexion. * **Largest Diameter:** Mentovertical (13.5 cm) – seen in brow presentation; usually necessitates a C-section. * **Mento-Vertical (MV):** 13.5 cm (Brow presentation). * **Submentobregmatic (SMB):** 9.5 cm (Face presentation). * **Occipitofrontal (OF):** 11.5 cm (Deflexed head/Military position). * **Biparietal Diameter (BPD):** 9.5 cm (Transverse diameter).

Question 842: The antiretroviral regime administration in the peripartum period decreases the risk of vertical transmission by:

A. 30%
B. 50% (Correct Answer)
C. 65%
D. 75%

Explanation: The risk of vertical transmission of HIV from mother to child occurs at three stages: intrauterine (in utero), intrapartum (during labor and delivery), and postpartum (through breastfeeding). **Explanation of the Correct Answer:** Without any intervention, the overall risk of mother-to-child transmission (MTCT) is approximately 25–30%. The **intrapartum period** is the most critical window, accounting for nearly **50-60%** of all transmissions due to fetal exposure to infected maternal blood and cervicovaginal secretions during labor. Administering an effective antiretroviral (ARV) regimen specifically during the peripartum period (labor and delivery) targets this high-risk window, effectively reducing the transmission risk by approximately **50%**. **Analysis of Incorrect Options:** * **A (30%):** This understates the impact of peripartum prophylaxis. While any ARV use helps, the specific reduction attributed to intrapartum intervention is more robust. * **C & D (65% & 75%):** These figures are more representative of the *cumulative* reduction seen when combining antenatal ARVs with intrapartum and neonatal prophylaxis. A full HAART (Highly Active Antiretroviral Therapy) regimen started early in pregnancy can reduce the risk to less than 1-2%. **NEET-PG High-Yield Pearls:** * **Most common route of MTCT:** Intrapartum (during labor). * **Drug of Choice (WHO/NACO):** TLE Regimen (Tenofovir + Lamivudine + Efavirenz) lifelong for the mother, regardless of CD4 count. * **Infant Prophylaxis:** Syrup Nevirapine for 6 weeks (extend to 12 weeks if maternal ART duration was <24 weeks). * **Mode of Delivery:** Elective Cesarean Section (at 38 weeks) is indicated only if the viral load is >1000 copies/mL or unknown. If the viral load is <50 copies/mL, vaginal delivery is preferred.

Question 843: All of the following are used in inherited thrombophilia testing in pregnancy, except:

A. Antithrombin deficiency
B. Protein C deficiency
C. Lupus anticoagulant (Correct Answer)
D. Factor V Leiden mutation

Explanation: **Explanation:** The core of this question lies in distinguishing between **inherited** and **acquired** thrombophilias. **Why Lupus Anticoagulant is the correct answer:** Lupus anticoagulant (LA) is a component of **Antiphospholipid Antibody Syndrome (APS)**, which is an **acquired** autoimmune thrombophilia. While it is a significant cause of recurrent pregnancy loss and maternal thrombosis, it is not a genetic/inherited condition. Therefore, it does not belong in a panel for *inherited* thrombophilia testing. **Analysis of incorrect options (Inherited Thrombophilias):** * **Antithrombin (AT) deficiency (Option A):** An inherited deficiency. It is the most thrombogenic of all inherited thrombophilias, carrying the highest risk of venous thromboembolism (VTE) during pregnancy. * **Protein C deficiency (Option B):** An inherited autosomal dominant condition. Along with Protein S deficiency, it leads to a failure in neutralizing Factors Va and VIIIa. * **Factor V Leiden mutation (Option C):** The **most common** inherited thrombophilia in Caucasian populations. It involves a point mutation that makes Factor V resistant to inactivation by activated Protein C. **Clinical Pearls for NEET-PG:** * **Most common inherited thrombophilia:** Factor V Leiden mutation. * **Highest risk of VTE in pregnancy:** Antithrombin III deficiency. * **Testing Caution:** Protein S levels naturally decrease during pregnancy; therefore, testing for Protein S deficiency is unreliable during the gestational period and should be done postpartum. * **Screening Indication:** Inherited thrombophilia screening is generally indicated for women with a personal history of VTE or a first-degree relative with high-risk thrombophilia.

Question 844: MgSO4 is contraindicated in eclampsia during treatment EXCEPT when which of the following occurs?

A. Urine output is < 30 ml/hr
B. Respiratory rate is < 16/min (Correct Answer)
C. Diastolic blood pressure is < 90 mmHg
D. Knee jerk is absent

Explanation: **Explanation:** Magnesium sulfate ($MgSO_4$) is the drug of choice for controlling and preventing seizures in eclampsia. However, it has a narrow therapeutic index and is excreted solely by the kidneys. Monitoring for magnesium toxicity is critical to prevent respiratory paralysis and cardiac arrest. **Why Option B is the Correct Answer:** The question asks when $MgSO_4$ is **NOT** contraindicated (i.e., when it can still be administered). According to standard protocols (Pritchard’s regimen), the clinical monitoring parameters for continuing $MgSO_4$ are: 1. **Respiratory Rate (RR) $\geq$ 12–14/min:** A rate of **16/min** is within the normal range and indicates no respiratory depression. Therefore, $MgSO_4$ is **not** contraindicated at this rate. 2. **Presence of Patellar Reflex (Knee Jerk):** Its disappearance is the first sign of toxicity. 3. **Urine Output $\geq$ 30 ml/hr:** To ensure adequate drug clearance. **Analysis of Incorrect Options:** * **Option A (Urine output < 30 ml/hr):** This indicates renal impairment. Since $MgSO_4$ is excreted by kidneys, continuing it would lead to toxic accumulation. * **Option D (Knee jerk is absent):** Loss of deep tendon reflexes (DTRs) occurs at plasma levels of 7–10 mEq/L and is the earliest warning sign of toxicity. Administration must be stopped. * **Option C (Diastolic BP < 90 mmHg):** While not a direct contraindication for $MgSO_4$ toxicity, it is irrelevant to the specific safety monitoring of Magnesium. $MgSO_4$ is an anticonvulsant, not primarily an antihypertensive. **High-Yield Clinical Pearls for NEET-PG:** * **Therapeutic range:** 4–7 mEq/L. * **Sequence of Toxicity:** Loss of Knee Jerk (7–10 mEq/L) $\rightarrow$ Respiratory Depression (11–15 mEq/L) $\rightarrow$ Cardiac Arrest (>15 mEq/L). * **Antidote:** 10 ml of 10% **Calcium Gluconate** IV (administered slowly over 10 minutes).

Question 845: A Rh negative G4P3+0 patient has an antibody level of 15 IU/ml (IAT 1:32) at 27 weeks gestation. What is the most appropriate next step in management?

A. Estimate amniotic fluid bilirubin levels
B. Estimate fetal hemoglobin levels by cordocentesis
C. Estimate middle cerebral artery peak systolic velocity (Correct Answer)
D. Perform intrauterine transfusion

Explanation: In Rh-isoimmunized pregnancies, the management goal is to detect fetal anemia before hydrops develops. **Explanation of the Correct Answer:** The patient is sensitized (Antibody titer ≥ 1:16 or > 4 IU/ml), which puts the fetus at risk for Hemolytic Disease of the Fetus and Newborn (HDFN). **Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV)** is the current gold standard for non-invasive screening of fetal anemia. * **Mechanism:** In fetal anemia, blood viscosity decreases and cardiac output increases to maintain oxygen delivery. This results in a higher velocity of blood flow. * **Threshold:** An MCA-PSV **> 1.5 MoM** (Multiples of Median) indicates severe anemia and is the trigger for invasive intervention. **Why Other Options are Incorrect:** * **A. Amniotic fluid bilirubin (Liley’s Chart):** Historically used to measure ΔOD450, this is now largely obsolete because it is invasive and less accurate than MCA-PSV, especially in the second trimester. * **B. Cordocentesis:** This is an invasive procedure with a 1-2% risk of fetal loss. It is used for definitive diagnosis and to prepare for transfusion, but it is not the *initial* screening step. * **D. Intrauterine Transfusion (IUT):** This is a therapeutic intervention, not a diagnostic step. It is only performed if fetal hemoglobin is confirmed to be < 7 g/dL or > 2 SD below the mean for gestational age. **Clinical Pearls for NEET-PG:** * **Critical Titer:** 1:16 is generally considered the threshold for monitoring; below this, the risk of hydrops is negligible. * **Best Timing:** MCA-PSV is most accurate between 18 and 35 weeks of gestation. * **First Step in Sensitized Pregnancy:** Always determine the paternal Rh status and zygosity first. If the father is heterozygous, fetal RHD genotyping (via cffDNA) is the next step.

Question 846: Monochorionic monoamniotic twin occurs if division occurs:

A. Before 24 hours
B. 1-4 days
C. 4-8 days
D. > 8 days (Correct Answer)

Explanation: The timing of the division of a single fertilized ovum determines the chorionicity and amniocity of monozygotic twins. The later the division occurs, the more structures the twins must share. **Explanation of the Correct Answer:** * **Option D (> 8 days):** If the zygote divides between **8 and 13 days** post-fertilization, the implantation has already occurred, and the amniotic sac has begun to form. Consequently, the twins will share a single placenta (Monochorionic) and a single amniotic sac (Monoamniotic). If division occurs even later (>13 days), it results in conjoined twins. **Analysis of Incorrect Options:** * **Option A & B (0–4 days):** Division at the **morula stage** (within the first 3–4 days) occurs before the differentiation of the trophoblast. This results in **Dichorionic Diamniotic (DCDA)** twins, where each fetus has its own placenta and sac. * **Option C (4–8 days):** Division at the **blastocyst stage** occurs after the trophoblast has differentiated but before the amnion forms. This results in **Monochorionic Diamniotic (MCDA)** twins, which is the most common type of monozygotic twinning (approx. 75%). **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic (Di-Di, Mo-Di, Mo-Mo):** * 0–4 days: **Di**-Di (2 chorions, 2 amnions) * 4–8 days: **Mo**-Di (1 chorion, 2 amnions) * 8–12 days: **Mo**-Mo (1 chorion, 1 amnion) * >13 days: Conjoined twins. * **T-sign vs. Lambda sign:** On ultrasound, the "T-sign" indicates Monochorionic twins, while the "Lambda (λ) or Twin-peak sign" indicates Dichorionic twins. * **Risk:** Mo-Mo twins carry the highest risk of cord entanglement and fetal demise, often requiring elective delivery between 32–34 weeks.

Question 847: A 24-year-old woman at 8 weeks of gestation presents with a history of pulmonary embolism 7 years ago during her first pregnancy. She was treated with intravenous heparin followed by several months of oral warfarin and has had no further evidence of thromboembolic disease for over 6 years. Which of the following statements about her current condition is true?

A. Having no evidence of disease for over 5 years means that the risk of thromboembolism is not greater than normal.
B. Impedance plethysmography is not a useful study to evaluate for deep venous thrombosis in pregnancy.
C. Doppler ultrasonography is not a useful technique to evaluate for deep venous thrombosis in pregnancy.
D. The patient should be placed on low-dose heparin therapy throughout pregnancy and puerperium. (Correct Answer)

Explanation: ### Explanation **1. Why Option D is Correct:** Pregnancy is a hypercoagulable state due to increased clotting factors and venous stasis. A history of pregnancy-associated venous thromboembolism (VTE) significantly increases the risk of recurrence in subsequent pregnancies (up to 10–15%). Current guidelines recommend **thromboprophylaxis** (typically with Low Molecular Weight Heparin or Unfractionated Heparin) for patients with a history of VTE related to a transient risk factor like pregnancy or OCP use. Prophylaxis should be maintained throughout the **antenatal period and for 6 weeks postpartum (puerperium)**, as the risk is highest during the first few weeks after delivery. **2. Why Other Options are Incorrect:** * **Option A:** The risk of VTE never returns to "normal" baseline once a patient has had a prior event. Even if the patient has been asymptomatic for years, the physiological changes of pregnancy act as a "second hit," necessitating prophylaxis. * **Option B & C:** Both **Impedance Plethysmography** and **Doppler Ultrasonography** are useful, non-invasive diagnostic tools for DVT in pregnancy. Compression Duplex Ultrasonography is currently the gold standard/initial investigation of choice for suspected DVT in pregnant women. **3. Clinical Pearls for NEET-PG:** * **Heparin vs. Warfarin:** Heparin (LMWH/UFH) is the drug of choice in pregnancy because it does not cross the placenta. Warfarin is generally contraindicated (except in mechanical heart valves) due to **Warfarin Embryopathy** (nasal hypoplasia, stippled epiphyses) and fetal hemorrhage. * **High-Yield Risk:** The most common site for DVT in pregnancy is the **left leg** (80% of cases) due to the compression of the left common iliac vein by the right common iliac artery (May-Thurner physiology). * **Postpartum Risk:** The risk of pulmonary embolism is higher in the postpartum period than during the pregnancy itself.

Question 848: Which of the following situations poses the greatest risk of Rh incompatibility?

A. Rh+ve mother with a second Rh-ve child
B. Rh-ve mother with a second Rh+ve child (Correct Answer)
C. Rh+ve mother with a first Rh-ve child
D. Rh-ve mother with a first Rh+ve child

Explanation: ### Explanation **Underlying Medical Concept:** Rh incompatibility occurs when an **Rh-negative mother** is exposed to **Rh-positive fetal red blood cells**, leading to the production of maternal anti-D antibodies (isoimmunization). This typically happens during the delivery of the first Rh-positive child. While the first child is usually unaffected because the primary immune response (IgM) is slow and cannot cross the placenta, subsequent Rh-positive pregnancies trigger a secondary immune response. This produces **IgG antibodies**, which cross the placenta and cause **Hemolytic Disease of the Fetus and Newborn (HDFN)**. **Analysis of Options:** * **Option B (Correct):** In a second Rh-positive pregnancy, the mother is already sensitized. Her immune system rapidly produces IgG antibodies that attack the fetal RBCs, posing the highest risk of clinical complications like hydrops fetalis. * **Option D (Incorrect):** While this is the "sensitizing" event, the first Rh-positive child is rarely affected because antibodies are not yet present in high titers during the pregnancy. * **Options A & C (Incorrect):** If the mother is **Rh-positive**, she already possesses the D-antigen. Her immune system recognizes Rh-positive cells as "self," so no antibodies are formed against the fetus, regardless of the child's Rh status. **High-Yield Clinical Pearls for NEET-PG:** * **Critical Titer:** An Indirect Coombs Test (ICT) titer of **1:16** is generally considered the critical threshold requiring fetal surveillance (e.g., MCA-PSV Doppler). * **Prophylaxis:** Administer **Anti-D Gamma Globulin (300 mcg)** at 28 weeks of gestation and within 72 hours of delivery if the neonate is Rh-positive. * **Kleihauer-Betke Test:** Used to quantify the volume of feto-maternal hemorrhage to calculate the required dose of Anti-D. * **First Sign on Ultrasound:** An increase in the **Middle Cerebral Artery Peak Systolic Velocity (MCA-PSV)** is the most sensitive non-invasive indicator of fetal anemia.

Question 849: Maternal near miss refers to:

A. Teenager becoming pregnant
B. Contraceptive failure in a teenager
C. A woman presenting with a life-threatening condition but has survived (Correct Answer)
D. A woman presenting with a life-threatening condition who has died

Explanation: ### Explanation **Maternal Near Miss (MNM)** is a critical concept in maternal health surveillance. According to the **WHO**, it is defined as "a woman who nearly died but survived a complication that occurred during pregnancy, childbirth, or within 42 days of termination of pregnancy." **1. Why Option C is Correct:** The core of the "Near Miss" concept is the **survival** of a life-threatening event. These cases share many pathological and logistical characteristics with maternal deaths. By studying survivors, clinicians can identify gaps in emergency obstetric care without the emotional and legal complexities often associated with mortality audits. **2. Analysis of Incorrect Options:** * **Option A & B:** These refer to adolescent pregnancy and contraceptive failure. While these are significant public health issues, they do not define a life-threatening clinical event or a "near-death" experience. * **Option D:** This describes a **Maternal Death**. A maternal death is the death of a woman while pregnant or within 42 days of termination, irrespective of the duration and site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management. **3. NEET-PG High-Yield Pearls:** * **Maternal Near Miss Ratio (MNMR):** The number of near-miss cases per 1,000 live births. * **Mortality Index:** Calculated as [Deaths / (Near Miss + Deaths)] × 100. A low index indicates high-quality emergency obstetric care. * **Identification Criteria:** WHO uses three criteria to identify MNM: **Clinical** (e.g., eclampsia), **Laboratory** (e.g., severe thrombocytopenia), and **Management-based** (e.g., use of mechanical ventilation or transfusion of >4 units of blood). * **The "Near Miss" to Death Ratio:** In well-functioning systems, there are usually many more near misses than actual deaths.

Question 850: What is the best method for diagnosing the degree of placenta previa?

A. Transvaginal sonography (Correct Answer)
B. Double set-up examination
C. Observation during Cesarean section
D. Examination of the placenta after delivery

Explanation: **Explanation:** **1. Why Transvaginal Sonography (TVS) is the Correct Answer:** Transvaginal sonography is currently the **gold standard** for diagnosing the degree and location of placenta previa. Unlike transabdominal scans (TAS), which can be obscured by maternal obesity, a full bladder (causing a false-positive diagnosis due to cervical compression), or the fetal head, TVS provides high-resolution images of the internal os and the placental edge. It is **safe, accurate, and superior** to TAS, with a sensitivity and specificity of nearly 100%. Contrary to old myths, TVS does not increase the risk of bleeding because the probe is not inserted into the cervical canal. **2. Why Other Options are Incorrect:** * **Double set-up examination:** Historically used to diagnose previa by palpating the cervix in an OR prepared for immediate CS. It is now **obsolete** and contraindicated due to the high risk of provoking massive hemorrhage. * **Observation during Cesarean section:** While this confirms the diagnosis, it is not a "diagnostic method" used for planning management; diagnosis must be established pre-operatively to determine the mode of delivery. * **Examination of the placenta after delivery:** This can show the distance from the tear to the placental edge, but it is a retrospective finding and has no clinical utility in active management. **Clinical Pearls for NEET-PG:** * **The "Gold Standard":** TVS is the investigation of choice. * **Safe Distance:** If the placental edge is **>2 cm** from the internal os, a vaginal delivery is usually successful. If it is **<2 cm or overlapping**, a Cesarean section is indicated. * **Warning:** Never perform a digital vaginal examination (PV) in a case of suspected placenta previa until the diagnosis is ruled out by ultrasound (the "Stallworthy’s sign" concept).

Practice by Chapter

Fetal Assessment Techniques

Practice Questions

Hypertensive Disorders in Pregnancy

Practice Questions

Intrauterine Growth Restriction

Practice Questions

Multiple Gestation

Practice Questions

Rh Isoimmunization and Other Blood Group Incompatibilities

Practice Questions

Intrauterine Fetal Therapy

Practice Questions

Prenatal Diagnosis and Genetic Counseling

Practice Questions

Placental Abnormalities

Practice Questions

Preterm Labor and Delivery

Practice Questions

Management of Medical Disorders in Pregnancy

Practice Questions

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