Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine Indian Medical PG Practice Questions and MCQs

Question 1351: All of the following statements are true regarding non-invasive prenatal screening (NIPT) test except:

A. High negative predictive value
B. Positive test needs further confirmation
C. Used in screening for aneuploidies
D. Evaluates fetal blood taken by cordocentesis for fetal abnormalities (Correct Answer)

Explanation: ***Evaluates fetal blood taken by cordocentesis for fetal abnormalities*** - NIPT evaluates **cell-free fetal DNA** from a maternal blood sample, not fetal blood obtained via cordocentesis. - **Cordocentesis** is an invasive diagnostic procedure used to obtain fetal blood, typically for rapid karyotyping or hematologic studies, and is not part of NIPT. *Positive test needs further confirmation* - NIPT is a **screening test**, and a positive result indicates an increased risk, not a definitive diagnosis. - Any positive NIPT result requires **confirmatory diagnostic testing**, such as amniocentesis or chorionic villus sampling (CVS), due to the possibility of false positives. *High negative predictive value* - NIPT has a **very high negative predictive value (NPV)**, meaning that a negative result reliably indicates a very low likelihood of the screened aneuploidies being present. - This high NPV makes NIPT an effective tool for **reassuring patients** with negative results and reducing the need for invasive diagnostic procedures. *Used in screening for aneuploidies* - NIPT is primarily used to screen for common **fetal aneuploidies**, such as **Trisomy 21 (Down syndrome)**, Trisomy 18 (Edwards syndrome), and Trisomy 13 (Patau syndrome). - It analyzes fragments of fetal DNA circulating in the maternal bloodstream to detect chromosomal dosage imbalances.

Question 1352: Placenta previa risk increases with the following except:

A. Maternal age >35 yrs
B. Multiparity
C. Contraceptive use (Correct Answer)
D. Previous cesarean section

Explanation: ***Contraceptive use*** - There is currently **no scientific evidence** to suggest that contraceptive use increases the risk of **placenta previa**. - Contraceptive use is not associated with placental implantation abnormalities in subsequent pregnancies. *Maternal age >35 yrs* - **Advanced maternal age** is a well-established risk factor for placenta previa, as the uterine lining may be less favorable for normal implantation in older women. - The risk of placental abnormalities, including **placenta previa**, increases with each decade of maternal age beyond 35 years. *Multiparity* - **Multiparity**, or having had multiple previous pregnancies, increases the risk of placenta previa. - This is thought to be due to **scarring or changes in the uterine lining** from previous pregnancies and deliveries, leading to preferential implantation in the lower uterine segment. *Previous cesarean section* - **Prior cesarean delivery** is one of the **most significant risk factors** for placenta previa. - Uterine scarring from cesarean section damages the endometrium, leading to abnormal placental implantation. - The risk increases with the **number of previous cesarean sections** and may lead to placenta previa with accreta spectrum disorders.

Question 1353: All of the following are the most commonly used ultrasonographic fetal growth parameters for estimating gestational age of the fetus, except:

A. Biparietal diameter
B. Head circumference
C. Transcerebellar diameter (Correct Answer)
D. Femur length

Explanation: ***Transcerebellar diameter*** - While it can be used for gestational age estimation, especially in cases of **intrauterine growth restriction (IUGR)** or during the third trimester, it is **not one of the most commonly used** or primary parameters for routine gestational age assessment in early pregnancy. - The transcerebellar diameter is less affected by **growth disturbances** compared to other parameters but is not part of the standard set of measurements. *Biparietal diameter* - This is a **primary and highly reliable parameter** for estimating gestational age, particularly in the **second trimester**. - It measures the distance between the two parietal bones of the fetal skull. *Head circumference* - **Head circumference** is another **standard and essential parameter** for estimating gestational age and assessing fetal growth. - It provides a comprehensive measurement of the fetal head. *Femur length* - **Femur length** is a **routinely used parameter** for estimating gestational age, especially from the end of the first trimester through the third trimester. - It measures the longest bone in the fetal body, the femur.

Question 1354: Fetal lung maturity assessed by all except -

A. Phosphatidyl choline concentration in amniotic fluid
B. Lecithin: sphingomyelin ratio
C. Measurement of alpha-fetoprotein (Correct Answer)
D. Lamellar body count

Explanation: ***Measurement of alpha-fetoprotein*** - **Alpha-fetoprotein (AFP)** is a marker for **neural tube defects** and **chromosomal abnormalities**, not fetal lung maturity. - While AFP is found in amniotic fluid, its levels do not correlate with the production of **surfactant** or the development of mature lung function. *Lecithin: sphingomyelin ratio* - The **lecithin: sphingomyelin (L:S) ratio** is a classic and reliable indicator of fetal lung maturity. - A ratio of **2:1 or higher** generally suggests sufficient **pulmonary surfactant** production, reducing the risk of **respiratory distress syndrome (RDS)**. *Phosphatidyl choline concentration in amniotic fluid* - **Phosphatidylcholine**, also known as **lecithin**, is a primary component of **surfactant**, which prevents alveolar collapse. - Measuring its concentration, specifically the **disaturated phosphatidylcholine (DSPC)**, directly assesses the lung's ability to produce adequate surfactant. *Lamellar body count* - **Lamellar bodies** are surfactant storage organelles secreted by type II pneumocytes into the amniotic fluid. - A count of **≥50,000/μL** indicates fetal lung maturity, and this test correlates well with the L:S ratio while being faster and more cost-effective.

Question 1355: A female of 36 weeks' gestation presents with severe hypertension, blurring of vision, and headache. Her blood pressure readings are 180/120 mmHg and 174/110 mmHg after 20 minutes. What is the most appropriate management for this patient?

A. Admit the patient, start antihypertensives, administer MgSO4, and plan for delivery. (Correct Answer)
B. Admit the patient and monitor her condition.
C. Discharge the patient with oral antihypertensives and schedule a follow-up.
D. Admit the patient, initiate antihypertensive therapy, and continue the pregnancy until term.

Explanation: ***Admit the patient, start antihypertensives, administer MgSO4, and plan for delivery.*** - The patient's symptoms (**severe hypertension**, **blurring of vision**, **headache**) at **36 weeks' gestation** indicate severe preeclampsia, necessitating immediate admission and management to prevent complications. - **Antihypertensives** are crucial to control severe hypertension, **magnesium sulfate (MgSO4)** prevents eclamptic seizures, and **delivery** is the definitive treatment for severe preeclampsia, especially near term. *Admit the patient and monitor her condition.* - While admission is correct, merely monitoring is insufficient given the patient's severe symptoms and high blood pressure readings, which indicate an urgent need for active management. - Delaying treatment could lead to serious maternal or fetal complications such as **eclampsia** or **placental abruption**. *Discharge the patient with oral antihypertensives and schedule a follow-up.* - Discharging a patient with severe preeclampsia is highly inappropriate and dangerous, as it puts both the mother and fetus at significant risk. - Oral antihypertensives alone are insufficient to manage severe preeclampsia acutely, and close monitoring and definitive treatment are required. *Admit the patient, initiate antihypertensive therapy, and continue the pregnancy until term.* - Although admitting the patient and starting antihypertensives are correct initial steps, continuing the pregnancy until term is generally not advisable with **severe preeclampsia** at **36 weeks' gestation**. - The risks associated with continuing the pregnancy often outweigh the benefits, and delivery is usually indicated to resolve the condition and prevent further progression.

Question 1356: What is the MOST common cause of elevated maternal serum alpha-fetoprotein in routine prenatal screening?

A. Maternal diabetes mellitus
B. Trisomy 21
C. Maternal hypertension
D. Open neural tube defect (Correct Answer)

Explanation: ***Open neural tube defect*** - **Open neural tube defects (NTDs)**, such as anencephaly or spina bifida, lead to direct leakage of **alpha-fetoprotein (AFP)** from the fetal circulation into the amniotic fluid and then into maternal blood. - Among **pathological fetal causes**, NTDs are the **most significant and commonly screened** condition associated with markedly elevated AFP in prenatal screening. - Note: Incorrect gestational age dating and multiple gestation are actually more common overall causes of elevated AFP, but among the fetal anomalies, **NTDs are the most important**. *Maternal diabetes mellitus* - Poorly controlled **maternal diabetes mellitus** is not a typical cause of elevated AFP. - While diabetes increases risk of fetal anomalies including **neural tube defects**, diabetes itself does not directly elevate AFP levels. *Trisomy 21* - **Trisomy 21 (Down syndrome)** is typically associated with **low maternal serum AFP levels**, not elevated levels. - Elevated AFP would suggest other conditions like NTDs rather than Trisomy 21. *Maternal hypertension* - **Maternal hypertension** is not directly associated with elevated maternal serum AFP. - While it can be linked to placental complications like **intrauterine growth restriction**, it does not typically cause significant AFP elevation.

Question 1357: Fetal immune response to Treponema pallidum becomes detectable at which week of pregnancy?

A. 4th week
B. 8th week
C. 18th week (Correct Answer)
D. 28th week

Explanation: ***Correct: 18th week*** - The **fetal immune system** is sufficiently developed by the **18th week of gestation** to mount a detectable immune response to *Treponema pallidum* - This marks the earliest point during pregnancy when **fetal IgM antibodies** specific to syphilis can be produced - Maternal treatment before 18 weeks can prevent fetal infection because the fetus cannot yet respond immunologically *Incorrect: 4th week* - At the **4th week of gestation**, the fetus is still in the **early embryonic stage**, and its immune system is not yet formed - No detectable **immune response** to any pathogen can be mounted at this very early stage *Incorrect: 8th week* - By the **8th week**, organogenesis is largely complete, but the **immune system is still immature** and not capable of a significant immune response - **Fetal antibody production** is extremely limited, if present at all, at this stage *Incorrect: 28th week* - While the fetal immune system is more robust by the **28th week**, the *Treponema pallidum* immune response is **detectable much earlier** (by 18 weeks) - A response by 28 weeks would indicate a **delayed diagnosis**, as the infection could have been identified sooner if screening occurred around 18 weeks

Question 1358: In a case of suspected Rh incompatibility in a pregnant woman, what is the next step in the investigation?

A. RhoGAM
B. Detection of fetal cells in maternal circulation
C. Direct Coomb's test
D. Indirect Coomb's test (Correct Answer)

Explanation: ***Indirect Coomb's test*** - The **indirect Coomb's test** (also known as the indirect antiglobulin test) identifies **Rh antibodies** in the mother's serum, indicating she has been sensitized to Rh-positive blood. - This test is crucial for determining if the mother is at risk of producing antibodies that could attack a subsequent Rh-positive fetus. *RhoGAM* - **RhoGAM** (Rh immunoglobulin) is a **preventive treatment** given to Rh-negative mothers, not a diagnostic test. - It works by neutralizing fetal Rh-positive red blood cells in the maternal circulation, preventing the mother's immune system from developing antibodies. *Direct Coomb's test* - The **direct Coomb's test** (or direct antiglobulin test) is performed on the **infant's blood** postnatal to detect antibodies already coating the infant's red blood cells. - This indicates that the infant's red blood cells have been attacked by maternal antibodies, suggesting hemolysis. *Detection of fetal cells in maternal circulation* - Detecting **fetal cells in maternal circulation** (e.g., using the Kleihauer-Betke test) is used to quantify the amount of **feto-maternal hemorrhage**. - This quantification helps determine the appropriate dose of RhoGAM needed after a potential exposure, such as trauma or delivery, but it doesn't diagnose the mother's sensitization status.

Question 1359: Nonimmune hydrops fetalis is caused by which of the following?

A. Cytomegalovirus (CMV)
B. Parvovirus B19 (Correct Answer)
C. Herpes Simplex Virus (HSV)
D. Human Immunodeficiency Virus (HIV)

Explanation: ***Parvovirus B19*** - **Parvovirus B19** infection in the fetus can lead to severe **anemia** due to its tropism for erythroid progenitor cells, which then causes **high-output cardiac failure** and subsequent **nonimmune hydrops fetalis**. - The anemia results in impaired oxygen delivery, leading to generalized edema and fluid accumulation in multiple fetal compartments, characteristic of hydrops fetalis. *Cytomegalovirus (CMV)* - While **CMV** is a common congenital infection and can cause significant fetal morbidity and mortality, it typically leads to symptoms like **microcephaly**, periventricular calcifications, and **sensorineural hearing loss**, rather than nonimmune hydrops fetalis as its primary presentation. - Though severe CMV can cause anemia and liver dysfunction, it is less commonly associated with the widespread edema and fluid accumulation seen in nonimmune hydrops compared to Parvovirus B19. *Herpes Simplex Virus (HSV)* - **HSV** infection in neonates is usually acquired during birth and can cause severe **skin lesions**, encephalitis, and disseminated disease, but it does not typically present as **nonimmune hydrops fetalis**. - Congenital HSV is very rare and symptoms when present are usually neurological or dermatological. *Human Immunodeficiency Virus (HIV)* - **HIV** infection in the fetus primarily results in **immunodeficiency** and increased susceptibility to opportunistic infections, often presenting with symptoms such as **failure to thrive**, recurrent infections, and developmental delays. - It is not a direct cause of **nonimmune hydrops fetalis**, which is characterized by widespread fluid accumulation due to circulatory or lymphatic issues.

Question 1360: A 24-year-old primigravida with HIV serology positive is in the antenatal outpatient department. Her CD4 count is 600 cells/μL, and her HIV-1 viral load is 2,680 copies/mL. Which of the following is the best method of reducing maternal-fetal transmission of HIV infection?

A. Elective cesarean section
B. Pooled intravenous immunoglobulin G therapy for the infant
C. Triple antiretroviral therapy for the mother throughout pregnancy (Correct Answer)
D. Nevirapine therapy for the infant after birth

Explanation: ***Triple antiretroviral therapy for the mother throughout pregnancy*** - **Antiretroviral therapy (ART)** during pregnancy is the most effective intervention to reduce **maternal-fetal HIV transmission**, as it significantly lowers the **maternal viral load**. - With a CD4 count of 600 cells/μL and viral load of 2,680 copies/mL, **immediate initiation of ART** is indicated to suppress viral replication. - This regimen ensures consistent suppression of the virus, reducing exposure to the fetus both **in-utero** and during **delivery**. - The goal is to achieve an **undetectable viral load (<50 copies/mL)** before delivery, which reduces transmission risk to **<1-2%**. *Elective cesarean section* - While an elective cesarean section can reduce transmission, it is **not the primary intervention** and is recommended as an adjunct when the **maternal viral load remains >1,000 copies/mL near term** (36-38 weeks) despite ART. - The mode of delivery decision is made based on viral load **near delivery**, not at initial presentation. - With effective ART lowering the viral load to undetectable levels, **vaginal delivery is appropriate** and cesarean section offers no additional benefit. *Pooled intravenous immunoglobulin G therapy for the infant* - **Intravenous immunoglobulin (IVIG)** therapy is not indicated for the prevention of **maternal-fetal HIV transmission** and does not directly target HIV. - IVIG is sometimes used in specific cases for infants with **immune deficiencies** or **severe infections** but not as a primary prophylactic measure for HIV. *Nevirapine therapy for the infant after birth* - While **nevirapine** or other antiretrovirals can be used as **post-exposure prophylaxis** for infants (typically started within 6-12 hours of birth), this is a **secondary prevention strategy**. - The most effective approach is to prevent infection in the first place through **maternal ART** throughout pregnancy, rather than relying solely on infant prophylaxis after potential exposure. - Infant prophylaxis is used as an **adjunct**, not a replacement, for maternal ART.

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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