Prenatal Care Practice Questions

Q: A couple with a child diagnosed with spina bifida presents for preconception counseling. What is the recurrence risk of spina bifida for this couple?

3-5%. Neural Tube Defects (NTDs), such as spina bifida and anencephaly, follow a **multifactorial inheritance** pattern. This means they result from a complex interaction between multiple genes and environmental factors (most notably folic acid deficiency). ### **Explanation of Options** * **Correct Option (A) 3-5%:** In multifactorial inheritance, the recurrence risk for a couple with one previously affected child is significantly higher than the general population risk (which is approximately 0.1-0.2%). For NTDs, the established recurrence risk after one affected sibling is **3% to 5%**. If two previous children are affected, the risk rises sharply to approximately **10%**. * **Incorrect Options (B, C, D):** These percentages (5-10% or >10%) overestimate the risk after only one affected child. A 10% risk is generally reserved for cases where there are two affected first-degree relatives. ### **High-Yield Clinical Pearls for NEET-PG** * **Folic Acid Prophylaxis:** * **Low Risk (General Population):** 0.4 mg (400 mcg) daily, starting 1 month before conception through the first trimester. * **High Risk (Previous child with NTD):** **4 mg (4000 mcg)** daily, starting at least 1–3 months before conception. This reduces the recurrence risk by approximately 70%. * **Screening:** Maternal Serum Alpha-Fetoprotein (MSAFP) is elevated in open NTDs. The ideal time for screening is **15–20 weeks** of gestation. * **Diagnosis:** Targeted Level II Ultrasound is the gold standard for diagnosing structural defects like spina bifida (look for the "lemon sign" and "banana sign" on cranial US).

Q: Maternal serum alpha-fetoprotein (MSAFP) is elevated in all of the following conditions EXCEPT:

Chromosomal trisomies. **Explanation:** Maternal Serum Alpha-Fetoprotein (MSAFP) is a glycoprotein produced initially by the yolk sac and later by the fetal liver. It enters the maternal circulation through fetal membranes and kidneys. The concentration of MSAFP is a crucial screening tool used between 15–20 weeks of gestation. **Why Chromosomal Trisomies is the Correct Answer:** In pregnancies affected by **Chromosomal Trisomies (such as Down Syndrome/Trisomy 21 and Edwards Syndrome/Trisomy 18)**, MSAFP levels are characteristically **decreased**, not elevated. In Down Syndrome, the mechanism is thought to involve reduced production by the fetal liver and a smaller-than-normal yolk sac. **Why the other options are incorrect (Conditions with Elevated MSAFP):** * **Neural Tube Defects (NTDs):** Conditions like anencephaly and spina bifida involve "open" defects where AFP leaks directly from the fetal serum/CSF into the amniotic fluid and subsequently into maternal serum. * **Esophageal Obstruction:** Any condition that interferes with fetal swallowing (e.g., esophageal or duodenal atresia) prevents the normal degradation of AFP in the fetal gut, leading to higher concentrations in the amniotic fluid and maternal serum. * **Gastroschisis/Omphalocele:** These are ventral wall defects where the fetal bowel or organs are exposed. Similar to NTDs, AFP leaks directly from the exposed fetal vessels into the amniotic fluid. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of elevated MSAFP:** Incorrect gestational age (underestimation of pregnancy dates). * **Other causes of elevated MSAFP:** Multiple gestations, fetal demise, renal anomalies (Finnish-type nephrosis), and placental abruption. * **Triple Test for Down Syndrome:** Decreased MSAFP, decreased unconjugated estriol (uE3), and **increased** hCG. * **Quadruple Test:** Adds **Inhibin-A**, which is **increased** in Down Syndrome.

Q: Increased alpha-fetoprotein (AFP) level is seen in which of the following conditions?

Incorrect gestational age dating. **Explanation:** Maternal Serum Alpha-Fetoprotein (MSAFP) is a crucial screening biomarker produced initially by the yolk sac and later by the fetal liver. Understanding its fluctuations is high-yield for NEET-PG. **Why "Incorrect gestational age dating" is correct:** The most common cause of an abnormal MSAFP level (either high or low) is **incorrect estimation of gestational age**. AFP levels in maternal serum rise progressively until 30–32 weeks of gestation. If a pregnancy is further advanced than clinically estimated (e.g., 18 weeks instead of 16 weeks), the AFP level will appear "elevated" relative to the expected median for the documented date. **Analysis of Incorrect Options:** * **Down’s Syndrome (Trisomy 21):** Characterized by **decreased** MSAFP levels. The classic "Triple Test" profile for Down’s is low AFP, low Unconjugated Estriol (uE3), and high hCG. * **Edward’s Syndrome (Trisomy 18):** Typically presents with **decreased** levels of all three markers (AFP, uE3, and hCG). * **Molar Pregnancy:** Associated with **decreased** MSAFP levels because there is no functional fetal liver or yolk sac to produce the protein, while hCG levels are pathologically elevated. **Clinical Pearls for NEET-PG:** * **Causes of Increased MSAFP:** Open Neural Tube Defects (e.g., Anencephaly, Spina Bifida), Abdominal wall defects (Omphalocele, Gastroschisis), Multiple gestations, and Fetal demise. * **Next Step:** When an elevated MSAFP is detected, the immediate next step is an **Ultrasonography** to confirm gestational age, exclude twins, and check for fetal viability. * **Amniotic AFP:** If MSAFP is high and ultrasound is inconclusive, amniocentesis is done to check amniotic fluid AFP and **Acetylcholinesterase (AChE)** levels; elevated AChE is specific for open neural tube defects.

Q: A 22-week pregnant woman has had exposure to rubella. What is the appropriate management?

Continue the pregnancy.. The management of Rubella exposure in pregnancy depends heavily on the **gestational age** at the time of infection. ### **Explanation of the Correct Answer** The risk of **Congenital Rubella Syndrome (CRS)** is highest during the first trimester (up to 80% risk before 12 weeks). As the pregnancy progresses, the risk of fetal malformations decreases significantly. By **20 weeks of gestation**, the risk of CRS becomes negligible. Since this patient is at **22 weeks**, the risk of congenital anomalies is minimal, and there is no indication for termination of pregnancy or aggressive intervention. Therefore, the appropriate management is to **continue the pregnancy** with routine antenatal care. ### **Why Other Options are Incorrect** * **Options A, B, and D:** The MMR vaccine is a **Live Attenuated Vaccine**. Live vaccines are strictly **contraindicated during pregnancy** due to the theoretical risk of the vaccine virus crossing the placenta and infecting the fetus. MMR should only be administered in the postpartum period to non-immune women. ### **NEET-PG High-Yield Pearls** * **Critical Period:** The highest risk for CRS is during the first **12 weeks** (organogenesis). After **16–20 weeks**, the risk of major defects is nearly zero. * **Classic Triad of CRS:** 1. Cataract, 2. Sensorineural hearing loss (most common), 3. Congenital heart disease (PDA/Pulmonary artery stenosis). * **Vaccination Timing:** If a woman receives the MMR vaccine, she should be advised to avoid pregnancy for at least **4 weeks (1 month)**. * **Diagnosis:** If exposure occurs <20 weeks, maternal IgM levels should be checked. If positive, fetal infection is confirmed via amniocentesis (PCR for Rubella RNA).

Q: What is the best method for confirming pregnancy at six weeks gestation?

Ultrasound for cardiac activity. **Explanation:** The gold standard for confirming a viable intrauterine pregnancy at six weeks gestation is the visualization of **fetal cardiac activity via Transvaginal Sonography (TVS)**. At this stage, a gestational sac and yolk sac should be visible, and the presence of a flickering cardiac motion within the fetal pole (embryo) provides definitive proof of life and viability. **Analysis of Options:** * **A. Ultrasound for cardiac activity (Correct):** TVS can detect cardiac activity as early as 5.5 to 6 weeks (when the Crown-Rump Length is approximately 2–5 mm). It is the most reliable method to differentiate a viable pregnancy from a missed abortion or a blighted ovum. * **B. Doppler assessment:** While Doppler can detect fetal heart sounds, it is generally not effective or recommended until **10–12 weeks** of gestation. Using it at 6 weeks is clinically premature and technically difficult. * **C. Estimation of serum beta-hCG:** While beta-hCG confirms "biochemical" pregnancy, it cannot confirm viability, location (intrauterine vs. ectopic), or gestational age as accurately as an ultrasound at 6 weeks. * **D. Bimanual palpation:** Physical signs like Hegar’s sign or uterine enlargement are subjective and typically become reliable only after **8–10 weeks**. It cannot confirm cardiac activity. **High-Yield NEET-PG Pearls:** * **Discriminatory Zone:** The level of beta-hCG at which a gestational sac should be visible on TVS is **1,500–2,000 mIU/mL**. * **First Sign on USG:** The **Gestational Sac** is the first evidence of pregnancy (4.5–5 weeks). * **Most Accurate Dating:** Crown-Rump Length (CRL) measured in the first trimester (7–12 weeks) is the most accurate method for pregnancy dating (error margin ± 3–5 days).

Q: Gestational sac can be seen using ultrasonography at the earliest by which week?

5th week. **Explanation:** The **Gestational Sac (GS)** is the first definitive sonographic sign of pregnancy. In a normal intrauterine pregnancy, it becomes visible on **Transvaginal Sonography (TVS)** at approximately **4.5 to 5 weeks** of gestation (calculated from the Last Menstrual Period). **1. Why 5th Week is Correct:** By the 5th week, the gestational sac typically measures 2–3 mm in diameter. It appears as a small, echo-free fluid collection surrounded by a thick echogenic rim (the decidual reaction), usually located eccentrically within the endometrial cavity. This timing corresponds to a serum **β-hCG "Discriminatory Zone"** of approximately 1,500–2,000 mIU/mL (TVS). **2. Analysis of Incorrect Options:** * **3rd Week:** At this stage, the blastocyst is just implanting. It is microscopically small and cannot be resolved by current ultrasound technology. * **4th Week:** While early decidual thickening may occur, a distinct gestational sac is rarely visible before 4.5 weeks. * **8th Week:** By the 8th week, the pregnancy is much further advanced; one would expect to see a yolk sac, an embryo with definite cardiac activity, and even early limb buds. **3. High-Yield Clinical Pearls for NEET-PG:** * **Order of Appearance (TVS):** Gestational Sac (5 weeks) → Yolk Sac (5.5 weeks) → Embryo/Cardiac activity (6 weeks). * **Double Decidual Sign:** Helps distinguish a true gestational sac from a "pseudogestational sac" (often seen in ectopic pregnancies). * **Mean Sac Diameter (MSD):** If the MSD is **>25 mm** and no embryo is visible, it indicates a failed pregnancy (Blighted Ovum). * **Transabdominal vs. Transvaginal:** TVS is generally 1 week more sensitive than Transabdominal Sonography (TAS), which visualizes the sac at approximately 6 weeks.

Q: Prenatal diagnosis at 16 weeks of pregnancy can be performed using which of the following methods?

Amniocentesis for amniotic fluid. ### Explanation The correct answer is **A. Amniocentesis for amniotic fluid**. **1. Why Amniocentesis is Correct:** Amniocentesis is the gold-standard invasive prenatal diagnostic procedure performed between **15 and 20 weeks** of gestation (ideally at 16 weeks). At this stage, there is sufficient amniotic fluid (approx. 150-200 mL) to safely withdraw 15-20 mL for fetal karyotyping, biochemical analysis, and DNA studies. The procedure involves ultrasound-guided needle aspiration of fluid containing desquamated fetal cells (amniocytes). **2. Why the Other Options are Incorrect:** * **B. Maternal blood for AFP levels:** This is a **screening test**, not a diagnostic test. While Maternal Serum Alpha-Fetoprotein (MSAFP) is measured between 15-20 weeks to screen for Neural Tube Defects (NTDs), a definitive diagnosis requires imaging or invasive testing. * **C. Chorionic Villus Sampling (CVS):** This is typically performed in the **first trimester**, between **10 and 13 weeks**. Performing it at 16 weeks is technically difficult and carries a higher risk of complications compared to amniocentesis. * **D. Fetal blood sampling (Cordocentesis):** Also known as Percutaneous Umbilical Blood Sampling (PUBS), this is usually performed **after 18 weeks** of gestation when the umbilical vein is large enough to be punctured safely. **3. High-Yield Clinical Pearls for NEET-PG:** * **Early Amniocentesis:** Performed before 15 weeks; it is generally avoided due to a higher risk of clubfoot (talipes equinovarus) and pregnancy loss. * **CVS vs. Amniocentesis:** CVS cannot diagnose Neural Tube Defects (as it doesn't measure AFP); Amniocentesis can. * **Most common complication:** For both procedures, the most common risk is fetal loss (approx. 0.5% for amniocentesis; 1% for CVS). * **Rh-Negative Mothers:** Always administer Anti-D immunoglobulin after any invasive prenatal procedure to prevent isoimmunization.

Question 1

A couple with a child diagnosed with spina bifida presents for preconception counseling. What is the recurrence risk of spina bifida for this couple?

Accepted Answer

3-5%

Answer

5-10%

Answer

10%

Answer

>10%

Question 2

Maternal serum alpha-fetoprotein (MSAFP) is elevated in all of the following conditions EXCEPT:

Accepted Answer

Chromosomal trisomies

Answer

Neural tube defects

Answer

Esophageal obstruction

Answer

Gastroschisis

Question 3

Increased alpha-fetoprotein (AFP) level is seen in which of the following conditions?

Accepted Answer

Incorrect gestational age dating

Answer

Down's syndrome

Answer

Molar pregnancy

Answer

Edward's syndrome

Question 4

What is a known hazard of chorionic villus sampling (CVS)?

Accepted Answer

Abortion

Answer

Limb abnormality

Answer

Spina bifida

Answer

Down's syndrome

Question 5

A 22-week pregnant woman has had exposure to rubella. What is the appropriate management?

Accepted Answer

Continue the pregnancy.

Answer

MMR vaccine should be given immediately.

Answer

MMR vaccine should be given in the 3rd trimester.

Answer

MMR vaccine should be given during labor.

Question 6

What is the best method for confirming pregnancy at six weeks gestation?

Accepted Answer

Ultrasound for cardiac activity

Answer

Doppler assessment

Answer

Estimation of serum beta-hCG

Answer

Bimanual palpation

Question 7

Gestational sac can be seen using ultrasonography at the earliest by which week?

Accepted Answer

5th week

Answer

3rd week

Answer

4th week

Answer

8th week

Question 8

A 31-year-old G3P2L2 presents at 34 weeks gestation with baseline blood pressures of 100-110/60-70 mmHg. She has bilateral pedal edema. Her urine dipstick shows trace protein, and her current blood pressure is 115/75 mmHg. On physical examination, there is pitting edema of both legs without any calf tenderness. What is the best management now?

Accepted Answer

This is a normal finding of pregnancy, and no treatment is needed.

Answer

Administer furosemide to reduce the swelling.

Answer

Perform urgent venous Doppler studies to rule out deep vein thrombosis.

Answer

Admit the patient and rule out preeclampsia.

Question 9

Prenatal diagnosis at 16 weeks of pregnancy can be performed using which of the following methods?

Accepted Answer

Amniocentesis for amniotic fluid

Answer

Maternal blood for AFP levels

Answer

Chorionic villus sampling

Answer

Fetal blood sampling

Question 10

While evaluating the heart of a 29-year old primigravida at term, you notice that there is an S2 and S3 which are easily audible and a systolic ejection murmur greater during inspiration. What do you recognize?

Accepted Answer

All findings recorded are normal changes in pregnancy.

Answer

The presence of S3 is abnormal.

Answer

The systolic ejection murmur is unusual in a pregnant woman at term.

Answer

Wide pulse pressure is rare in pregnant women.

Prenatal Care — MCQs

Prenatal Care — MCQs

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