Prenatal Care — MCQs

Prenatal Care Indian Medical PG Practice Questions and MCQs

Question 251: What is the first step in managing a patient presenting with a post-dated pregnancy?

A. Perform Ultrasound (USG)
B. Conduct Non-stress Test (NST)
C. Review menstrual history for accuracy (Correct Answer)
D. Obtain X-ray of the abdomen

Explanation: The management of post-dated pregnancy (pregnancy exceeding 40 weeks) begins with confirming the diagnosis. The most common cause of an apparent post-dated pregnancy is **incorrect dating** due to irregular cycles or inaccurate recall of the Last Menstrual Period (LMP). ### Why "Review menstrual history" is correct: Before initiating any intervention or fetal surveillance, the clinician must verify the **Estimated Date of Confinement (EDC)**. This involves reviewing the menstrual history (regularity of cycles, use of oral contraceptives) and comparing it with early clinical findings (first-trimester ultrasound or date of quickening). If the dates are inaccurate, the pregnancy may not actually be post-dated, thereby preventing unnecessary inductions and their associated risks (e.g., failed induction, increased C-section rates). ### Why other options are incorrect: * **Perform Ultrasound (USG):** While USG is used for dating, its accuracy decreases significantly in the third trimester (error margin of ±3 weeks). It is used to assess liquor volume (AFI) *after* the dates are confirmed. * **Conduct Non-stress Test (NST):** This is a part of fetal surveillance (Biophysical Profile). It is performed once the diagnosis of post-term pregnancy is established to ensure fetal well-being, but it is not the *first* step. * **Obtain X-ray of the abdomen:** This is obsolete in modern obstetrics due to radiation risks and the availability of superior modalities like USG. ### High-Yield Clinical Pearls for NEET-PG: * **Definition:** Post-term pregnancy is $\geq$ 42 weeks (294 days); Post-dated is $> 40$ weeks. * **Gold Standard for Dating:** Crown-Rump Length (CRL) measured via USG between 7–11 weeks is the most accurate predictor of gestational age. * **Management Rule:** If dates are confirmed, fetal surveillance (NST + AFI) usually begins at 40 weeks + 3 days or 41 weeks, with induction recommended by 41 weeks + 6 days to prevent **Dysmaturity Syndrome** and stillbirth.

Question 252: Manual appreciation of fetal "quickening" by examination is earliest possible at which week of gestation?

A. 20 (Correct Answer)
B. 24
C. 26
D. 28

Explanation: **Explanation:** The correct answer is **20 weeks (Option A)**. **Understanding the Concept:** "Quickening" refers to the first perception of fetal movements. While the mother feels these movements internally, they can be appreciated externally by a clinician through abdominal palpation (manual appreciation). * **Maternal perception:** In primigravida, it occurs at **18–20 weeks**; in multigravida, it occurs earlier at **16–18 weeks**. * **Clinical appreciation:** A clinician can typically palpate fetal movements through the maternal abdominal wall starting around the **20th week** of gestation. This coincides with the fundal height reaching the level of the umbilicus, making the uterus more accessible for manual examination. **Analysis of Incorrect Options:** * **Option B (24 weeks):** By this stage, fetal movements are very distinct and can be easily seen (visible movements), but the *earliest* point of manual detection has already passed. * **Options C & D (26 and 28 weeks):** These represent later stages of the second and third trimesters. While movements are stronger and more frequent, they do not represent the "earliest" possible detection. **High-Yield Clinical Pearls for NEET-PG:** * **Fundal Height Rule:** At 20 weeks, the fundus is usually at the lower border of the umbilicus (or 2 fingerbreadths below). * **Quickening Significance:** It is a subjective sign of pregnancy and helps in cross-checking the Expected Date of Delivery (EDD), especially in women with irregular periods. * **Fetal Heart Sounds (FHS):** Can be heard by a stethoscope at **18–20 weeks** and by Doppler as early as **10–12 weeks**. * **Ultrasound:** Fetal cardiac activity can be seen on Transvaginal Sonography (TVS) as early as **6 weeks**.

Question 253: Which of the following statements regarding cell-free DNA is FALSE?

A. It is detected in maternal blood.
B. Prenatal diagnosis of Down's syndrome can be made using it.
C. It is used for liquid biopsy.
D. It is an invasive technique for prenatal diagnosis of certain genetic diseases. (Correct Answer)

Explanation: **Explanation:** The correct answer is **D** because cell-free DNA (cfDNA) screening is a **non-invasive** prenatal testing (NIPT) method. It involves a simple maternal blood draw (venipuncture), which poses no risk of miscarriage, unlike invasive procedures such as Amniocentesis or Chorionic Villus Sampling (CVS). **Analysis of Options:** * **Option A:** cfDNA consists of short fragments of DNA found circulating in the **maternal blood**. In pregnancy, these fragments originate primarily from the apoptotic trophoblast cells of the placenta (often called cell-free fetal DNA). * **Option B:** cfDNA is highly sensitive and specific for screening aneuploidies. It is currently the most effective screening tool for **Down’s Syndrome (Trisomy 21)**, with a detection rate >99%. However, it remains a screening test; positive results require confirmation via invasive testing. * **Option C:** In oncology, cfDNA is the basis for **"liquid biopsy,"** allowing clinicians to detect tumor-derived DNA (ctDNA) in a patient's blood to monitor cancer mutations and treatment response without a tissue biopsy. **Clinical Pearls for NEET-PG:** * **Fetal Fraction:** For a valid NIPT result, the fetal fraction (percentage of cfDNA that is fetal) must typically be **>4%**. It is usually detectable after **10 weeks** of gestation. * **Source:** Remember, "fetal" DNA in maternal blood actually reflects the **genetic makeup of the placenta** (trophoblasts), which can occasionally lead to "confined placental mosaicism." * **Vanishing Twin:** A common cause of false-positive results in cfDNA testing is a co-twin demise.

Question 254: Air travel in pregnancy is generally permitted up to which gestational age?

A. 28 weeks
B. 32 weeks
C. 36 weeks (Correct Answer)
D. 40 weeks

Explanation: **Explanation:** Air travel is generally considered safe for healthy pregnant women. According to guidelines from the **ACOG (American College of Obstetricians and Gynecologists)** and **RCOG**, the most common cutoff for domestic air travel in an uncomplicated singleton pregnancy is **36 weeks**. 1. **Why 36 weeks is correct:** The primary concern with late-term air travel is not the altitude or pressure, but the risk of **spontaneous labor** or rupture of membranes occurring while in flight, away from specialized obstetric care. By 36 weeks, the risk of labor increases significantly. For international flights, some airlines may have stricter cutoffs (often 32–35 weeks). 2. **Why other options are incorrect:** * **28 weeks:** This is often the threshold where airlines require a "Fit to Fly" certificate from a doctor, but it is not the limit for travel. * **32 weeks:** This is the recommended cutoff for **uncomplicated multiple pregnancies** (e.g., twins) due to the higher risk of preterm labor. * **40 weeks:** Traveling at term is contraindicated as labor is imminent, and the environment of a commercial aircraft is unequipped for delivery or neonatal emergencies. **High-Yield Clinical Pearls for NEET-PG:** * **Best time to travel:** The **second trimester** (14–28 weeks) is the safest period because the risks of miscarriage and preterm labor are lowest, and morning sickness has usually subsided. * **DVT Prophylaxis:** Pregnancy is a hypercoagulable state. To prevent Deep Vein Thrombosis (DVT) during long flights, patients should be advised to wear **compression stockings**, stay hydrated, and perform frequent calf exercises or walk every hour. * **Contraindications:** Air travel should be avoided in women with severe anemia, sickle cell disease (risk of crisis due to low partial pressure of oxygen), or obstetric complications like placenta previa or preeclampsia.

Question 255: Appropriate material for antenatal diagnosis of genetic disorders includes all of the following except?

A. Fetal blood
B. Amniotic fluid
C. Chorionic villi
D. Maternal urine (Correct Answer)

Explanation: **Explanation:** The goal of prenatal genetic diagnosis is to obtain fetal genetic material (DNA or chromosomes) to identify abnormalities. **Maternal urine (Option D)** is the correct answer because it does not contain fetal cells or cell-free fetal DNA in sufficient quantity or quality to be used for diagnostic genetic testing. While maternal blood can be used for screening (NIPT), urine remains clinically irrelevant for genetic diagnosis. **Analysis of other options:** * **Fetal Blood (Option A):** Obtained via **Cordocentesis** (Percutaneous Umbilical Blood Sampling). It provides rapid fetal karyotyping and is the gold standard for diagnosing fetal hematological disorders or infections. It is usually performed after 18 weeks. * **Amniotic Fluid (Option B):** Obtained via **Amniocentesis** (typically between 15–20 weeks). It contains desquamated fetal cells (amniocytes) which are cultured for karyotyping, biochemical analysis, and DNA studies. * **Chorionic Villi (Option C):** Obtained via **Chorionic Villus Sampling (CVS)**. This is the preferred method for early diagnosis (10–13 weeks) as it samples the trophoblastic tissue, which shares the fetal genetic makeup. **High-Yield NEET-PG Pearls:** 1. **Earliest Diagnostic Test:** CVS (10–13 weeks). 2. **Most Common Diagnostic Test:** Amniocentesis (15–20 weeks). 3. **NIPT (Non-Invasive Prenatal Testing):** Uses **maternal blood** to analyze cell-free fetal DNA (cffDNA). It is a *screening* test, not a *diagnostic* test. 4. **Risk of Procedure-related Loss:** CVS (~0.5–1%) carries a slightly higher risk of miscarriage compared to mid-trimester amniocentesis (~0.1–0.5%). 5. **Limb Reduction Defects:** A known complication if CVS is performed before 9-10 weeks of gestation.

Question 256: Raised beta-hCG levels are seen in which of the following conditions?

A. Diabetes Mellitus
B. Preeclampsia
C. Ectopic pregnancy
D. Rh incompatibility (Correct Answer)

Explanation: **Explanation:** The correct answer is **Rh incompatibility**. **1. Why Rh Incompatibility is Correct:** In Rh-isoimmunization, maternal antibodies cross the placenta and cause fetal hemolysis. To compensate for the resulting fetal anemia, the placenta undergoes **hypertrophic changes (placentomegaly)**. The increased mass of the cytotrophoblasts and syncytiotrophoblasts leads to an overproduction of human chorionic gonadotropin (hCG). Therefore, raised maternal serum beta-hCG levels are a characteristic finding in severe Rh-isoimmunization and hydrops fetalis. **2. Analysis of Incorrect Options:** * **Diabetes Mellitus:** While DM is associated with large placentas, beta-hCG levels are typically **normal** or only slightly altered; they are not a diagnostic or characteristic marker for the condition. * **Preeclampsia:** This condition is associated with placental ischemia and "placental aging." While some studies show elevated hCG in severe cases due to trophoblastic hyperproliferation, it is **not** the classic association compared to Rh incompatibility in standard textbooks. * **Ectopic Pregnancy:** This is a high-yield distractor. In ectopic pregnancy, beta-hCG levels are **lower than expected** for the period of gestation and fail to show the normal doubling (at least 66% increase) every 48 hours. **3. NEET-PG High-Yield Pearls:** * **Conditions with Raised beta-hCG:** Molar pregnancy (highest levels), Multiple pregnancy, Rh-isoimmunization, Down Syndrome (Triple/Quadruple screen), and Choriocarcinoma. * **Conditions with Low beta-hCG:** Ectopic pregnancy, Threatened/Spontaneous abortion, and Edwards Syndrome (Trisomy 18). * **Doubling Time:** In a healthy intrauterine pregnancy, beta-hCG doubles every 48–72 hours until it peaks at 8–11 weeks.

Question 257: A 32-year-old mother, who has previously had a child with Down syndrome, is now 9 weeks pregnant and wishes to avoid having another child with Down syndrome. As her physician, what would you advise?

A. Ultrasound at this stage can confirm the presence or absence of Down syndrome.
B. Chorionic villous sampling at this stage can confirm the presence or absence of Down syndrome. (Correct Answer)
C. The triple test or maternal AFP screening at this stage can confirm the presence or absence of Down syndrome.
D. No intervention is necessary as the risk is minimal because her age is less than 35 years.

Explanation: ### Explanation **1. Why Option B is Correct:** The patient is currently at **9 weeks of gestation** and has a high-risk history (previous child with Down syndrome). **Chorionic Villous Sampling (CVS)** is the preferred invasive diagnostic test in the first trimester (typically performed between **10–13 weeks**, though some protocols begin at 9 weeks). Unlike screening tests, CVS provides a definitive **fetal karyotype**, allowing for the confirmation or exclusion of chromosomal aneuploidies like Trisomy 21 early in pregnancy. **2. Why Other Options are Incorrect:** * **Option A:** Ultrasound (specifically Nuchal Translucency) is a **screening tool**, not a diagnostic one. It can suggest an increased risk but cannot "confirm" the presence or absence of Down syndrome. Furthermore, NT is ideally measured between 11 and 13+6 weeks. * **Option C:** The Triple Test and Maternal Serum AFP are **second-trimester screening tests** (performed between 15–20 weeks). They are biochemical markers with lower sensitivity than invasive testing and cannot provide a definitive diagnosis. * **Option D:** While maternal age <35 reduces baseline risk, a **previous history of a child with a trisomy** significantly increases the recurrence risk (approx. 1% or the age-related risk, whichever is higher). Therefore, intervention and counseling are mandatory. **3. High-Yield Clinical Pearls for NEET-PG:** * **Definitive Diagnosis:** Only Karyotyping/FISH via CVS or Amniocentesis is diagnostic. * **Timing:** * CVS: 10–13 weeks (Risk: 0.5–1% miscarriage; limb reduction defects if done <9 weeks). * Amniocentesis: 15–20 weeks (Risk: 0.5% miscarriage). * **Screening Gold Standard:** The **Combined Test** (NT + PAPP-A + hCG) is the best first-trimester screen. * **Recurrence Risk:** For a mother with a previous Down syndrome child, the risk of recurrence in subsequent pregnancies is roughly **1%**.

Question 258: What is the best test for estimating human chorionic gonadotropin (hCG)?

A. Radioimmunoassay (Correct Answer)
B. Enzyme-linked immunosorbent assay (ELISA)
C. Radioreceptor assay
D. Bioassay

Explanation: **Explanation:** The estimation of human chorionic gonadotropin (hCG) is fundamental in diagnosing pregnancy, monitoring ectopic pregnancies, and managing gestational trophoblastic diseases. **Why Radioimmunoassay (RIA) is the correct answer:** Radioimmunoassay is considered the "Gold Standard" for the quantitative estimation of hCG. Its superiority lies in its **extreme sensitivity and specificity**. RIA utilizes the **beta-subunit (β-hCG)** principle, which prevents cross-reactivity with Luteinizing Hormone (LH), as both share an identical alpha-subunit. It can detect hCG levels as low as 5 mIU/mL, making it the most reliable test for early pregnancy detection and monitoring biochemical markers in oncology. **Analysis of Incorrect Options:** * **ELISA:** While widely used for routine pregnancy tests (Urine/Serum) due to its speed and lack of radiation, it is generally less sensitive than RIA for precise quantification in a laboratory setting. * **Radioreceptor Assay:** This test measures the biological activity of hCG by its ability to bind to receptors. However, it cannot distinguish between hCG and LH, leading to high false-positive rates. * **Bioassay:** These are historical tests (e.g., Aschheim-Zondek, Friedman test) involving animal models. They are obsolete due to being time-consuming, expensive, and lacking precision. **NEET-PG High-Yield Pearls:** * **Doubling Time:** In a healthy intrauterine pregnancy, serum β-hCG levels double every **48 hours**. * **Discriminatory Zone:** The level of hCG at which a gestational sac should be visible on TVS is **1500–2000 mIU/mL**. * **Peak Levels:** hCG levels reach their peak at **8–10 weeks** of gestation (approx. 100,000 mIU/mL) and then decline. * **Source:** hCG is secreted by the **syncytiotrophoblast** cells of the placenta.

Question 259: Which of the following supplements is recommended for a pregnant patient receiving antiepileptic drugs to decrease the risk of neural tube defects in the offspring?

A. Folic acid (Correct Answer)
B. Vitamin A
C. Vitamin E
D. Pyridoxine

Explanation: **Explanation:** **1. Why Folic Acid is Correct:** Neural Tube Defects (NTDs) occur due to the failure of the neural tube to close during the first 28 days of gestation. Antiepileptic drugs (AEDs), particularly **Valproate, Carbamazepine, and Phenytoin**, interfere with folate metabolism (antagonism), significantly increasing the risk of NTDs. Supplementation with Folic acid before conception and during the first trimester is the standard of care to mitigate this risk. * **High-Yield Note:** While the standard dose for low-risk pregnancies is 400 mcg (0.4 mg), women on AEDs are considered **high-risk** and require a higher dose of **4 mg (4000 mcg)** daily, starting at least one month prior to conception. **2. Why Other Options are Incorrect:** * **Vitamin A:** Excessive intake (Retinoids) is actually **teratogenic**, leading to craniofacial, cardiac, and CNS defects (Retinoic acid embryopathy). It is not used to prevent NTDs. * **Vitamin E:** This is an antioxidant. While it has been studied for pre-eclampsia prevention, it has no proven role in preventing NTDs or counteracting AED-induced teratogenicity. * **Pyridoxine (Vitamin B6):** Primarily used in pregnancy to treat **Nausea and Vomiting of Pregnancy (NVP)** or to prevent peripheral neuropathy in patients taking Isoniazid. It does not prevent NTDs. **Clinical Pearls for NEET-PG:** * **Best time to start:** Pre-conceptionally (ideally 3 months before). * **Valproate:** Carries the highest risk of NTDs (specifically spina bifida) and cognitive impairment. * **Vitamin K:** Some guidelines recommend Vitamin K supplementation (10 mg/day) in the last month of pregnancy for women on enzyme-inducing AEDs (like Phenobarbital) to prevent neonatal hemorrhagic disease, though Folic acid remains the priority for NTDs.

Question 260: Amniocentesis to detect chromosomal abnormalities can be performed as early as which week of gestation?

A. 14th week of gestation (Correct Answer)
B. 18th week of gestation
C. 22nd week of gestation
D. 26th week of gestation

Explanation: **Explanation:** **Amniocentesis** is an invasive prenatal diagnostic procedure involving the aspiration of amniotic fluid for genetic, chromosomal, or biochemical analysis. **1. Why Option A is Correct:** The standard window for genetic amniocentesis is between **15 and 20 weeks** of gestation. However, it can be performed as early as the **14th week** once the amnion and chorion have fused. Before 14 weeks, there is often a "non-fusion" space between these membranes, making the procedure technically difficult and increasing the risk of fetal injury or procedure failure. Performing it at the 14th week ensures sufficient amniotic fluid volume (approx. 150-200 mL) to safely withdraw the required 20 mL sample. **2. Why Other Options are Incorrect:** * **Options B, C, and D:** While amniocentesis *can* be performed at 18, 22, or 26 weeks (e.g., for Rh isoimmunization or fetal lung maturity), these options do not represent the **earliest** possible timeframe for detecting chromosomal abnormalities. Late amniocentesis is generally avoided for primary screening because it delays the diagnosis beyond the legal or safe limit for elective termination of pregnancy in many regions. **3. NEET-PG High-Yield Pearls:** * **Early Amniocentesis:** Defined as being performed between **11–13 weeks**. It is generally **discouraged** due to a higher risk of pregnancy loss and fetal talipes equinovarus (clubfoot). * **Chorionic Villus Sampling (CVS):** Performed earlier than amniocentesis, typically between **10–13 weeks**. * **Most Common Complication:** Fetal loss (approx. 0.1% to 0.3% in modern practice). * **Anti-D Immunoglobulin:** Must be administered to all **Rh-negative** unsensitized women following the procedure to prevent isoimmunization.

Practice by Chapter

Preconception Counseling

Practice Questions

Pregnancy Diagnosis and Dating

Practice Questions

Routine Antenatal Assessments

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Maternal Physiological Changes

Practice Questions

Nutrition in Pregnancy

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Screening Tests in Pregnancy

Practice Questions

Fetal Growth Assessment

Practice Questions

High-Risk Pregnancy Identification

Practice Questions

Antenatal Complications Management

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Psychosocial Aspects of Pregnancy

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