Prenatal Care Practice Questions

Q: All of the following can be used to determine a chromosome analysis of the fetus except?

Fetal umbilical Doppler velocimetry. **Explanation:** The core concept here is distinguishing between **invasive diagnostic procedures** (which obtain fetal cells for genetic analysis) and **non-invasive screening/surveillance tools** (which assess fetal well-being and hemodynamics). **Why Option D is correct:** **Fetal umbilical Doppler velocimetry** is a non-invasive ultrasound technique used to assess placental resistance and fetal blood flow. It measures the ratio of systolic to diastolic flow in the umbilical artery. It is used to monitor fetuses with Intrauterine Growth Restriction (IUGR) or Rh isoimmunization, but it **cannot** provide genetic material or cells for chromosomal analysis (karyotyping). **Why the other options are incorrect:** * **A. Amniocentesis:** The gold standard for prenatal diagnosis. It involves aspirating amniotic fluid containing fetal desquamated cells (amniocytes), which are cultured for karyotyping. Usually performed at 15–20 weeks. * **B. Chorionic Villus Sampling (CVS):** Involves taking a biopsy of the placental trophoblastic tissue. It provides fetal cells for rapid chromosomal analysis and can be performed earlier than amniocentesis (10–13 weeks). * **C. Percutaneous Umbilical Blood Sampling (PUBS):** Also known as Cordocentesis. It involves ultrasound-guided aspiration of fetal blood directly from the umbilical vein. It provides the fastest karyotype results (within 48–72 hours) via lymphocyte culture. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Diagnostic Test:** CVS (10–13 weeks). * **Most Common Diagnostic Test:** Amniocentesis. * **Fastest Karyotype:** PUBS/Cordocentesis. * **Risk of Limb Reduction Defects:** Associated with CVS if performed before 9–10 weeks. * **Doppler Significance:** "Absent or Reversed End-Diastolic Velocity" (AEDV/REDV) on umbilical Doppler is a critical sign of fetal compromise requiring urgent intervention.

Q: All of the following disorders can be diagnosed antenatally except?

Pernicious anaemia. **Explanation:** The core concept behind this question lies in the distinction between **genetic (inherited) disorders** and **acquired nutritional deficiencies**. **Why Pernicious Anaemia is the correct answer:** Pernicious anaemia is an **autoimmune condition** characterized by the production of antibodies against gastric parietal cells or intrinsic factor, leading to Vitamin B12 deficiency. It is an acquired condition that typically manifests in later adulthood. Since it is not caused by a specific, single-gene mutation detectable in fetal DNA, it cannot be diagnosed antenatally through standard prenatal screening or invasive testing (like CVS or Amniocentesis). **Why the other options are incorrect:** * **Hemophilia (A & B):** These are X-linked recessive bleeding disorders. They can be diagnosed antenatally by identifying the specific mutation in the F8 or F9 gene via Chorionic Villus Sampling (CVS). * **Thalassemia:** This is an autosomal recessive hemoglobinopathy. It is routinely diagnosed antenatally using DNA analysis of fetal tissue to look for alpha or beta-globin gene mutations. * **Sickle Cell Anemia:** Similar to Thalassemia, this is a point mutation in the HBB gene. It is easily detectable through molecular genetic testing of fetal cells. **NEET-PG High-Yield Pearls:** * **Prenatal Diagnostic Tools:** Genetic disorders (Options A, B, C) are diagnosed using **CVS (10–13 weeks)** or **Amniocentesis (15–20 weeks)**. * **Most Common Indication:** The most common indication for invasive prenatal diagnosis worldwide is advanced maternal age, but in India, it is frequently performed for **Thalassemia major** screening. * **Karyotyping vs. DNA Analysis:** Karyotyping is used for chromosomal anomalies (e.g., Down Syndrome), while DNA analysis (PCR) is used for Mendelian disorders like Hemophilia and Thalassemia.

Q: What is the ideal time for screening of blood sugar for diabetes in a pregnant female?

24-28 weeks. **Explanation:** The correct answer is **C. 24-28 weeks.** **Why 24-28 weeks is the ideal time:** Pregnancy is a state of progressive insulin resistance. This is primarily due to the secretion of **diabetogenic hormones** by the placenta, most notably **Human Placental Lactogen (hPL)**, along with cortisol, prolactin, and progesterone. These hormones peak during the late second and early third trimesters. Screening at 24-28 weeks captures the period when insulin resistance becomes significant enough to manifest as Gestational Diabetes Mellitus (GDM) in susceptible women. **Analysis of Incorrect Options:** * **A, B, & D (12-24 weeks):** While screening can be done earlier, it is generally reserved for high-risk patients (e.g., history of GDM, obesity, or PCOS). In a low-risk or routine screening scenario, testing before 24 weeks may yield a false negative because the physiological insulin resistance has not yet reached its peak. **High-Yield Clinical Pearls for NEET-PG:** * **DIPSI Guidelines (India):** A single-step 75g Oral Glucose Tolerance Test (OGTT) is recommended. A 2-hour plasma glucose value **≥140 mg/dL** is diagnostic of GDM, regardless of the last meal. * **Early Screening:** If a woman has high-risk factors, screen at the **first prenatal visit**. If negative, repeat the test at 24-28 weeks. * **Postpartum Follow-up:** Women with GDM should be screened for Type 2 Diabetes **6-12 weeks postpartum** using a 75g OGTT. * **Most common fetal complication:** Fetal macrosomia (due to fetal hyperinsulinemia). * **Most common fetal malformation in Pre-gestational Diabetes:** Caudal Regression Syndrome (though Ventricular Septal Defect is the most common cardiac defect).

Q: What is the most specific marker for neural tube defects?

Acetylcholinesterase. **Explanation:** The diagnosis of Neural Tube Defects (NTDs) involves a sequential screening and diagnostic process. **Why Acetylcholinesterase (AChE) is the correct answer:** While Alpha-fetoprotein (AFP) is the primary screening tool, **Acetylcholinesterase (AChE)** is the most specific biochemical marker. AChE is an enzyme found in high concentrations within neural tissue. In cases of open NTDs (like anencephaly or open spina bifida), the fetal cerebrospinal fluid—which contains this enzyme—leaks directly into the amniotic fluid. Detecting AChE via amniocentesis (using gel electrophoresis) confirms the presence of exposed neural tissue, effectively ruling out false positives caused by other conditions. **Analysis of Incorrect Options:** * **Alpha-fetoprotein (AFP):** This is a highly **sensitive** screening marker but lacks specificity. Elevated levels can occur in multiple gestations, omphalocele, gastroschisis, pilonidal cysts, or even due to incorrect gestational dating. * **Pseudocholinesterase:** This enzyme is found in the liver and serum but is not specific to neural tissue. It does not serve as a diagnostic marker for NTDs. * **Inhibin:** Inhibin-A is a component of the "Quadruple Screen" used primarily to screen for **Down Syndrome** (where it is elevated) and Trisomy 18, not NTDs. **NEET-PG High-Yield Pearls:** * **Best Screening Test:** Maternal Serum Alpha-fetoprotein (MSAFP) at 15–20 weeks. * **Best Diagnostic Investigation:** Targeted Level II Ultrasound (the "Gold Standard" in modern practice). * **Lemon Sign & Banana Sign:** Classic ultrasound findings associated with Spina Bifida. * **Prevention:** 400 mcg of Folic Acid daily (pre-conceptionally) reduces NTD risk by 70%; 4 mg is required for women with a previous affected pregnancy.

Q: At what period of gestation is a detailed survey for fetal anomalies typically performed?

18-20 weeks. **Explanation:** The **Anomaly Scan** (also known as the Level II ultrasound or Mid-trimester morphology scan) is ideally performed between **18 and 20 weeks** of gestation. **Why 18-20 weeks is the correct answer:** At this gestational age, fetal organogenesis is complete, and the fetus has reached a size where the internal anatomy (especially the four-chamber heart, kidneys, and spine) can be visualized with high resolution. Additionally, the volume of amniotic fluid is relatively large compared to the fetus, providing an excellent acoustic window for detailed imaging. **Analysis of Incorrect Options:** * **12-14 weeks:** This is the window for the **NT (Nuchal Translucency) scan**. While major defects like anencephaly can be seen, the organs are too small for a "detailed" survey. * **14-16 weeks:** The heart and brain structures are still developing and are often too small for a definitive structural evaluation. * **16-18 weeks:** While some anomalies are visible, visualization of the cardiac outflow tracts and certain neural tube defects is less reliable than at 18-20 weeks. **High-Yield Clinical Pearls for NEET-PG:** * **Soft Markers:** The scan looks for markers like choroid plexus cysts, echogenic intracardiac focus (EIF), and single umbilical artery, which may indicate underlying chromosomal issues. * **TIFFA:** This scan is often referred to as **TIFFA** (Targeted Imaging for Fetal Anomalies). * **Legal Limit:** In India, under the MTP Act (Amendment 2021), the upper limit for termination of pregnancy for substantial fetal abnormalities is not restricted by a 24-week ceiling if approved by a Medical Board, making the 18-20 week window crucial for timely decision-making.

Q: What is the best method for localizing the placenta?

Ultrasonogram. **Explanation:** The localization of the placenta is a critical step in prenatal care, primarily to rule out **Placenta Previa**. **Why Ultrasonogram (USG) is the best method:** Ultrasonography is the **gold standard** and the investigation of choice for placental localization. It is non-invasive, safe (no ionizing radiation), easily available, and highly accurate (95–98% sensitivity). Transvaginal Sonography (TVS) is considered superior to Transabdominal Sonography (TAS) as it provides better visualization of the internal os and the lower uterine segment, even in cases of a posterior placenta. **Why other options are incorrect:** * **Vaginal Examination:** This is **strictly contraindicated** in cases of suspected placenta previa (unless performed as a "Double Setup" in an OT) because it can provoke massive, life-threatening hemorrhage by disturbing the placental attachment. * **Amniography:** This involves injecting radiopaque dye into the amniotic sac. It is an obsolete, invasive technique that carries risks of infection, fetal injury, and radiation exposure. * **Uteroscopy:** This is not a standard tool for placental localization. It is invasive and carries a high risk of rupturing membranes or causing hemorrhage. **High-Yield Clinical Pearls for NEET-PG:** * **Investigation of Choice:** Transvaginal Ultrasound (TVS) is safer and more accurate than TAS for measuring the distance between the placental edge and the internal os. * **Placental Migration:** The placenta may appear "low-lying" in the second trimester but "move" away from the os as the lower uterine segment develops (Trohotropism). * **MRI:** Reserved for suspected **Placenta Accreta Spectrum** when USG results are inconclusive. * **Warning:** Never perform a per-vaginal (PV) exam in a pregnant woman with bleeding (APH) until placenta previa is ruled out by USG.

Q: What is the best serological marker for Down syndrome in the first trimester?

beta-hCG. **Explanation:** In the first trimester (11–13.6 weeks), the standard screening for Down syndrome (Trisomy 21) is the **Combined Test**, which includes maternal age, fetal nuchal translucency (NT), and two biochemical markers: **Pregnancy-associated plasma protein A (PAPP-A)** and **free beta-hCG**. **Why beta-hCG is correct:** Among the biochemical markers, **free beta-hCG is significantly elevated** in pregnancies affected by Down syndrome. Conversely, PAPP-A levels are characteristically decreased. While both are used, beta-hCG is the primary serological marker associated with an increased risk of Trisomy 21 in the first trimester. **Analysis of Incorrect Options:** * **A. Nuchal translucency (NT):** While NT is the most sensitive *ultrasound* marker for Down syndrome, the question specifically asks for a **serological** (blood) marker. * **B. Skeletal abnormalities:** These (such as a short femur or humerus) are "soft markers" typically identified during the second-trimester anomaly scan (18–20 weeks), not the first trimester. * **D. Serum estriol (uE3):** Unconjugated estriol is a component of the **Triple or Quadruple marker test**, which is performed in the **second trimester** (15–20 weeks). In Down syndrome, estriol levels are decreased. **High-Yield Clinical Pearls for NEET-PG:** * **First Trimester (Combined Test):** ↑ beta-hCG, ↓ PAPP-A, ↑ NT. * **Second Trimester (Quad Test):** ↑ beta-hCG, ↑ Inhibin A, ↓ AFP, ↓ uE3 (Mnemonic: **HI** is **High**—**H**CG and **I**nhibin are elevated). * **Confirmatory Test:** Chorionic Villus Sampling (10–13 weeks) or Amniocentesis (15–20 weeks). * **NIPT (Cell-free DNA):** The most sensitive screening tool overall (detection rate >99%), but it is not categorized as a traditional "serological marker" in this context.

Q: Which of the following hematological parameters remains unchanged during pregnancy?

Mean Corpuscular Hemoglobin Concentration (MCHC). In pregnancy, the maternal body undergoes significant physiological adaptations to support the growing fetus. Understanding the distinction between absolute changes and red cell indices is crucial for NEET-PG. ### **Why MCHC is the Correct Answer** **Mean Corpuscular Hemoglobin Concentration (MCHC)** represents the concentration of hemoglobin in a given volume of packed red blood cells. While both the total hemoglobin and the Mean Corpuscular Volume (MCV) may fluctuate slightly, the **MCHC remains constant** in a healthy pregnancy. This is because the individual red blood cells maintain their hemoglobin saturation levels despite the overall expansion of blood volume. ### **Analysis of Incorrect Options** * **A. Blood Volume:** This **increases** significantly (by 40–50%). Plasma volume increases more than red cell mass, leading to "physiological anemia of pregnancy." * **B. Total Iron-Binding Capacity (TIBC):** This **increases**. As iron stores are utilized and serum iron levels fall, the liver produces more transferrin, leading to a rise in TIBC. * **D. Serum Ferritin:** This **decreases**. Ferritin is the primary storage form of iron. Due to the high demand for iron by the fetus and the expansion of maternal red cell mass, storage levels typically drop, especially in the second and third trimesters. ### **High-Yield Clinical Pearls for NEET-PG** * **MCV (Mean Corpuscular Volume):** Usually remains unchanged or may show a very slight increase. * **ESR (Erythrocyte Sedimentation Rate):** Increases significantly due to increased fibrinogen levels (making it an unreliable marker for infection in pregnancy). * **Clotting Factors:** Pregnancy is a **hypercoagulable state**. Factors VII, VIII, IX, X, and Fibrinogen increase, while Protein S levels decrease. * **Leukocytosis:** The total WBC count increases during pregnancy (up to 12,000/mm³) and can peak up to 25,000/mm³ during labor.

Question 1

A 36-year-old woman with a long history of epilepsy is contemplating pregnancy and is concerned about the potential adverse effects of her anticonvulsant medications on her fetus. Which of the following statements regarding epilepsy and pregnancy is FALSE?

Accepted Answer

Phenytoin (Dilantin) is associated with a 1 to 2% risk of spina bifida.

Answer

The risk of structural anomalies in babies born to mothers with epilepsy is increased, even without anticonvulsant medication use.

Answer

Neurologists should attempt to wean epileptic women off their anticonvulsant medications prior to conception.

Answer

Folic acid supplementation can reduce the risk of congenital anomalies in fetuses of epileptic women taking anticonvulsants.

Question 2

All of the following can be used to determine a chromosome analysis of the fetus except?

Accepted Answer

Fetal umbilical Doppler velocimetry

Answer

Amniocentesis

Answer

Chorionic villus sampling

Answer

Percutaneous umbilical blood sampling (PUBS)

Question 3

All of the following disorders can be diagnosed antenatally except?

Accepted Answer

Pernicious anaemia

Answer

Hemophilia

Answer

Thalassemia

Answer

Sickle cell anemia

Question 4

What is the ideal time for screening of blood sugar for diabetes in a pregnant female?

Accepted Answer

24-28 weeks

Answer

16-20 weeks

Answer

20-24 weeks

Answer

12-16 weeks

Question 5

What is the most specific marker for neural tube defects?

Accepted Answer

Acetylcholinesterase

Answer

Alpha fetoprotein

Answer

Pseudocholinesterase

Answer

Inhibin

Question 6

All of the following are normal physiological changes in pregnancy except?

Accepted Answer

ALP

Answer

ALT and AST

Answer

Prothrombin time

Answer

GGT

Question 7

At what period of gestation is a detailed survey for fetal anomalies typically performed?

Accepted Answer

18-20 weeks

Answer

12-14 weeks

Answer

14-16 weeks

Answer

16-18 weeks

Question 8

What is the best method for localizing the placenta?

Accepted Answer

Ultrasonogram

Answer

Vaginal examination

Answer

Amniography

Answer

Uteroscopy

Question 9

What is the best serological marker for Down syndrome in the first trimester?

Accepted Answer

beta-hCG

Answer

Nuchal translucency

Answer

Skeletal abnormalities

Answer

Serum estriol

Question 10

Which of the following hematological parameters remains unchanged during pregnancy?

Accepted Answer

Mean Corpuscular Hemoglobin Concentration (MCHC)

Answer

Blood Volume

Answer

Total Iron-Binding Capacity (TIBC)

Answer

Serum Ferritin

Prenatal Care — MCQs

Prenatal Care — MCQs

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