Prenatal Care Practice Questions

Q: Amniocentesis is done for all of the mentioned indications EXCEPT?

Oligohydramnios. **Explanation:** Amniocentesis is a procedure where amniotic fluid is aspirated from the gravid uterus for diagnostic or therapeutic purposes. The correct answer is **Oligohydramnios** because it is a **contraindication** (or a technical limitation) rather than an indication. 1. **Why Oligohydramnios is the Correct Answer:** Amniocentesis requires an adequate pocket of amniotic fluid to safely insert the needle without injuring the fetus or the umbilical cord. In oligohydramnios (decreased fluid volume), the risk of fetal injury and "dry tap" (failure to obtain fluid) is significantly high. In fact, amniocentesis is often used to *treat* polyhydramnios (therapeutic amnioreduction), not oligohydramnios. 2. **Analysis of Other Options:** * **Fetal Lung Maturity:** Historically, the L/S ratio (Lecithin/Sphingomyelin) and Phosphatidylglycerol levels were measured via amniocentesis to assess lung maturity before elective preterm delivery. * **Congenital Infections:** Amniotic fluid PCR is the gold standard for diagnosing intrauterine infections like TORCH (especially CMV and Toxoplasmosis). * **Genetic Defects:** This is the most common indication. Amniotic fluid contains desquamated fetal cells (amniocytes) used for karyotyping, FISH, and chromosomal microarray to detect Down syndrome and other aneuploidies. **NEET-PG High-Yield Pearls:** * **Timing:** Ideally performed between **15–20 weeks** of gestation. * **Early Amniocentesis:** Done between 12–14 weeks; however, it is associated with a higher risk of clubfoot (talipes equinovarus) and procedure loss. * **Risk of Fetal Loss:** Approximately 0.5% (1 in 200). * **Rh-Negative Mothers:** Always administer Anti-D immunoglobulin after the procedure to prevent isoimmunization.

Q: Fetal length is affected if the mother has undernutrition during which period of gestation?

Any time during the pregnancy. **Explanation:** The correct answer is **D. Any time during the pregnancy.** **Medical Concept:** Fetal growth is a continuous process characterized by three distinct cellular phases: **Hyperplasia** (increase in cell number), **Hypertrophy** (increase in cell size), and a combined phase. 1. **First Trimester:** Growth is primarily via cellular hyperplasia. Undernutrition here leads to a decrease in the total number of cells, resulting in overall growth restriction. 2. **Second Trimester:** Growth involves both hyperplasia and hypertrophy. 3. **Third Trimester:** Growth is predominantly via cellular hypertrophy and fat deposition. Since fetal length (linear growth) and weight are cumulative results of these processes, severe maternal undernutrition at **any stage** of gestation can impair the specific cellular activity occurring at that time, ultimately affecting the final fetal length. **Analysis of Incorrect Options:** * **A, B, and C:** While the *rate* of growth varies (weight gain is maximal in the third trimester, while linear growth is rapid in the second), nutritional insults are not restricted to a specific window. Restricting the answer to a single trimester ignores the fact that the skeletal template is formed early and elongated continuously. **High-Yield Clinical Pearls for NEET-PG:** * **Symmetric IUGR:** Caused by factors acting early in pregnancy (e.g., chromosomal anomalies, early infections, or severe early undernutrition). Both head and body are proportionately small. * **Asymmetric IUGR:** Usually caused by placental insufficiency in the **third trimester**. The head is spared (Brain Sparing Effect), but the abdominal circumference is reduced. * **Ponderal Index:** Used to differentiate between symmetric and asymmetric IUGR. * **Most sensitive parameter** for detecting IUGR on ultrasound is the **Abdominal Circumference (AC)**.

Q: A high level of hCG is seen in all of the following conditions EXCEPT:

Neural tube defect. **Explanation:** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone produced by the syncytiotrophoblast. Understanding its variations is crucial for prenatal screening and oncology. **Why Neural Tube Defects (NTDs) is the correct answer:** In cases of **Neural Tube Defects** (like anencephaly or spina bifida), the primary biochemical marker that increases is **Alpha-Fetoprotein (AFP)**, due to leakage from the exposed fetal tissues. hCG levels typically remain **normal** in isolated NTDs. Therefore, it is the "except" in this list. **Analysis of Incorrect Options:** * **Down Syndrome (Trisomy 21):** In the second-trimester quadruple screen, Down syndrome is characterized by **elevated hCG** and Inhibin-A, while AFP and unconjugated Estriol (uE3) are decreased (Mnemonic: **HI**gh for **H**CG and **I**nhibin). * **Gestational Trophoblastic Disease (GTD):** Conditions like Hydatidiform mole involve massive proliferation of trophoblastic tissue, leading to **extremely high levels of hCG** (often >100,000 mIU/mL). * **Germ Cell Tumors:** Certain ovarian or testicular germ cell tumors, specifically **Choriocarcinomas** and some Dysgerminomas/Embryonal carcinomas, secrete hCG as a tumor marker. **High-Yield NEET-PG Pearls:** * **Low hCG levels** are associated with: Ectopic pregnancy (lower than expected for gestational age), threatened abortion, and Edwards syndrome (Trisomy 18). * **High hCG levels** are also seen in: Multiple pregnancies and Rh isoimmunization (due to placental hydrops). * **AFP** is the marker of choice for NTDs; it is **decreased** in Down syndrome.

Q: A 18-week pregnant multigravida, Rh-negative, with a previous child born with a chromosomal abnormality, underwent cordocentesis. Which test is used to differentiate between maternal and fetal blood in a given sample?

Apt test. **Explanation:** The correct answer is the **Apt test** (Alkali Denaturation Test). This test is specifically designed to differentiate between fetal and maternal blood based on the biochemical properties of hemoglobin. **1. Why the Apt test is correct:** Fetal hemoglobin (**HbF**) is resistant to denaturation by strong bases, whereas adult hemoglobin (**HbA**) is not. In this test, the blood sample is mixed with 1% sodium hydroxide (NaOH). If the blood is maternal (HbA), it denatures and turns **yellow-brown**. If the blood is fetal (HbF), it remains stable and stays **pink**. This is crucial during cordocentesis to ensure the sample obtained is truly fetal blood and not contaminated by maternal blood. **2. Why the other options are incorrect:** * **Kleihauer-Betke test:** This is used to **quantify** the amount of fetal-maternal hemorrhage (FMH) in the maternal circulation (e.g., to calculate the dose of Anti-D). It is an acid-elution test performed on a maternal blood smear, not a direct test to identify the source of a sample. * **Osmotic fragility test:** Used primarily to diagnose **Hereditary Spherocytosis** by measuring the resistance of RBCs to hemolysis in hypotonic solutions. * **Bubble stability test:** A bedside test used to assess **fetal lung maturity** by checking for the presence of surfactants in amniotic fluid. **Clinical Pearls for NEET-PG:** * **Apt Test Uses:** Differentiating fetal from maternal blood in cases of **Vasa Previa** (vaginal bleeding) or during **Cordocentesis**. * **Cordocentesis (PUBS):** Usually performed after 18 weeks; the most common site is the umbilical vein at the placental insertion. * **Kleihauer-Betke Formula:** Fetal cells counted / Total cells × 5000 = Volume of FMH (mL). This is a high-yield calculation for Rh-isoimmunization questions.

Question 1

As an isolated finding, which of the following is associated with the highest risk of Down syndrome?

Accepted Answer

Increased nuchal fold thickness

Answer

Shortened femur

Answer

Absence of nasal bone

Answer

Echogenic bowel

Question 2

Myelodysplasia in a fetus can be best diagnosed by which of the following methods?

Accepted Answer

Alpha-fetoprotein (AFP)

Answer

Lumbar puncture

Answer

Human chorionic gonadotropin (HCG)

Answer

Unconjugated estriol

Question 3

Amniocentesis is done for all of the mentioned indications EXCEPT?

Accepted Answer

Oligohydramnios

Answer

Fetal lung maturity

Answer

Congenital infections

Answer

Genetic defects

Question 4

What is the appropriate treatment for a woman experiencing edema during pregnancy?

Accepted Answer

Bed rest

Answer

Salt restriction

Answer

Fluid restriction

Answer

Diuretics

Question 5

A 32-year-old G3P20L2 presents to the obstetrician's office for a routine OB visit at 30 weeks gestation. She has had no complications during the pregnancy and has had regular prenatal care. Her gestational age is confirmed with a first-trimester sonogram. During the routine OB visit, the fundal height measures 35 cm. All of the following can explain the size-date discrepancy except?

Accepted Answer

The 5-cm difference is within the error for fundal height measurements

Answer

Leiomyomas

Answer

Polyhydramnios

Answer

Fetal macrosomia

Question 6

Fetal length is affected if the mother has undernutrition during which period of gestation?

Accepted Answer

Any time during the pregnancy

Answer

First trimester

Answer

Second trimester

Answer

Third trimester

Question 7

What is the recommended daily dose of folic acid for a pregnant woman in the first trimester with a history of neural tube defects (NTD)?

Accepted Answer

4 mg

Answer

100 micrograms

Answer

400 micrograms

Answer

5 mg

Question 8

A high level of hCG is seen in all of the following conditions EXCEPT:

Accepted Answer

Neural tube defect

Answer

Down syndrome

Answer

Germ cell tumor

Answer

Gestational trophoblastic disease

Question 9

A 18-week pregnant multigravida, Rh-negative, with a previous child born with a chromosomal abnormality, underwent cordocentesis. Which test is used to differentiate between maternal and fetal blood in a given sample?

Accepted Answer

Apt test

Answer

Kleihauer-Betke test

Answer

Osmotic fragility test

Answer

Bubble stability test

Question 10

Which of the following is true about chorionic villi biopsy?

Accepted Answer

Rh immunoglobulin prophylaxis is not necessary

Answer

Strongly associated with fetal limb defects

Answer

Done between 10-12 weeks of gestation

Answer

Done to diagnose genetic disorders

Prenatal Care — MCQs

Prenatal Care — MCQs

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