Maternal-Fetal Medicine Practice Questions

Q: Which of the following sites are the rarest and most common for ectopic pregnancy, respectively?

Cervix and ampulla of fallopian tube. **Explanation:** Ectopic pregnancy occurs when a fertilized ovum implants outside the normal uterine cavity. Understanding the distribution of these sites is a high-yield topic for NEET-PG. **1. Why Option C is Correct:** * **Most Common Site:** The **Fallopian tube** accounts for approximately 95–97% of all ectopic pregnancies. Within the tube, the **Ampulla** is the most frequent site (approx. 70%) due to its wide lumen and mucosal folds where fertilization typically occurs. * **Rarest Site:** The **Cervix** is considered the rarest site of implantation, occurring in <1% of cases. It is clinically significant due to the high risk of massive hemorrhage during management. **2. Analysis of Incorrect Options:** * **Option A:** While the Ampulla is the most common, the Ovary (approx. 3%) is more common than the cervix. * **Option B:** The Isthmus is the second most common tubal site (approx. 12%), but not the most common overall. The Broad ligament (intraligamentary) is rare but usually occurs secondary to tubal rupture. * **Option D:** Abdominal pregnancies (approx. 1%) are rare but still occur more frequently than cervical pregnancies in most epidemiological studies. **3. NEET-PG Clinical Pearls:** * **Order of Frequency in Fallopian Tube:** Ampulla (70%) > Isthmus (12%) > Fimbria (11%) > Interstitial/Cornual (2–3%). * **Highest Risk of Rupture:** The **Isthmus** tends to rupture early (6–8 weeks) because it is narrow and non-distensible. * **Most Dangerous Site:** **Interstitial/Cornual** pregnancies are the most dangerous because they rupture late (12–14 weeks) and cause massive, life-threatening hemorrhage due to the proximity of the uterine artery. * **Classic Triad:** Amenorrhea, abdominal pain, and vaginal bleeding (present in only 50% of cases).

Q: Amniotic fluid volume in polyhydramnios is more than:

2000ml. **Explanation:** **Polyhydramnios** is defined as a pathological increase in amniotic fluid volume during pregnancy. By standard clinical definition, polyhydramnios occurs when the total volume of amniotic fluid exceeds **2000 ml** at any point during gestation. 1. **Why 2000 ml is correct:** Amniotic fluid volume increases progressively until 34–36 weeks, peaking at approximately 800–1000 ml. A volume exceeding 2000 ml is considered abnormal and is associated with maternal complications (like respiratory distress or preterm labor) and fetal anomalies (like esophageal atresia or neural tube defects). 2. **Why other options are incorrect:** * **500 ml:** This is within the normal range for mid-pregnancy. A volume below 200 ml is termed oligohydramnios. * **1000 ml:** This represents the physiological peak of amniotic fluid at 36 weeks; it is the upper limit of normal, not polyhydramnios. * **1500 ml:** While this is an excessive amount, it does not meet the formal diagnostic threshold of 2000 ml used in obstetric textbooks (e.g., Williams Obstetrics, Dutta). **High-Yield Clinical Pearls for NEET-PG:** * **Sonographic Diagnosis:** Polyhydramnios is diagnosed via ultrasound if the **Amniotic Fluid Index (AFI) is >25 cm** or the **Single Deepest Pocket (SDP) is >8 cm**. * **Most Common Cause:** Idiopathic (50–60%), followed by maternal diabetes and fetal structural anomalies. * **Complications:** Malpresentation, cord prolapse, placental abruption (due to sudden decompression), and Postpartum Hemorrhage (PPH) due to uterine atony. * **Management:** Therapeutic amniocentesis (amniodrainage) or Indomethacin (which decreases fetal urine production) may be used in severe cases.

Q: Which of the following measures the amount of fetal blood entering maternal circulation?

Kleihauer-Betke test. ### Explanation **1. Why Kleihauer-Betke (KB) Test is Correct:** The **Kleihauer-Betke test** is the gold standard for quantifying the volume of **fetal-maternal hemorrhage (FMH)**. It relies on the principle that **Fetal Hemoglobin (HbF)** is resistant to acid elution, whereas Adult Hemoglobin (HbA) is not. When a maternal blood smear is treated with an acid buffer, HbA is leached out of the adult cells (leaving them as "ghost cells"), while HbF remains intact. The percentage of fetal cells is then used to calculate the required dose of **Anti-D immunoglobulin** to prevent Rh isoimmunization. **2. Analysis of Incorrect Options:** * **B. Singer’s Test:** This is a chemical method (alkali denaturation) used to estimate the percentage of HbF in a blood sample, but it is not used to quantify fetal cells in maternal circulation for FMH. * **C. APT Test:** This is a qualitative test used to differentiate fetal blood from maternal blood in cases of **antepartum hemorrhage** (e.g., vasa previa) or neonatal gastric aspirate (to see if the baby swallowed maternal blood during delivery). It uses NaOH; fetal blood stays pink, while maternal blood turns yellow-brown. * **D. Benedict Test:** This is a classic biochemistry test used to detect **reducing sugars** (like glucose) in the urine. **3. High-Yield Clinical Pearls for NEET-PG:** * **Formula for Anti-D:** Volume of FMH (mL) = % of fetal cells × 50. One 300 mcg vial of Anti-D covers **30 mL** of fetal whole blood (or 15 mL of fetal RBCs). * **Screening vs. Quantification:** The **Rosette Test** is the initial *qualitative* screening test for FMH. If positive, the KB test is performed for *quantification*. * **False Positives:** Conditions with high maternal HbF (e.g., Beta-thalassemia trait, Sickle cell anemia, or Hereditary Persistence of Fetal Hemoglobin) can cause a false-positive KB test.

Q: In diabetic pregnancy, which of the following is least common?

Caudal regression syndrome. In diabetic pregnancies, the risk of congenital malformations is 3–4 times higher than in the general population, primarily due to poor glycemic control during organogenesis. **Explanation of the Correct Answer:** While **Caudal Regression Syndrome** (sacral agenesis) is the **most specific** malformation associated with maternal diabetes (with a relative risk over 200 times higher than the general population), it is actually the **least common** in terms of absolute frequency. In exams, students often confuse "most specific" with "most common." Because the baseline incidence of caudal regression is extremely low, it remains a rare finding compared to other defects. **Analysis of Incorrect Options:** * **Ventricular Septal Defect (VSD):** This is the **most common** congenital malformation seen in infants of diabetic mothers. Cardiovascular anomalies, specifically VSD and Transposition of the Great Arteries (TGA), occur more frequently than any other system defects. * **Anencephaly and Spina Bifida:** Neural Tube Defects (NTDs) are the second most common group of malformations in diabetic pregnancies. The risk of NTDs like anencephaly and spina bifida is increased 10-fold in diabetic mothers compared to the general population. **NEET-PG High-Yield Pearls:** * **Most Specific Malformation:** Caudal Regression Syndrome. * **Most Common Malformation:** Cardiovascular anomalies (specifically VSD). * **Most Common Neonatal Complication:** Hypoglycemia. * **HbA1c Correlation:** The risk of malformations increases significantly if HbA1c is >8.5% during the first trimester. * **Note:** Gestational Diabetes (GDM) usually does not increase the risk of these malformations because hyperglycemia typically develops after the period of organogenesis.

Q: Which of the following is NOT a common cause of placenta accreta?

Previous abruptio placenta. **Explanation:** The core pathophysiology of **Placenta Accreta Spectrum (PAS)** is a defect in the **decidua basalis** (specifically the Nitabuch layer), which allows placental villi to invade the myometrium directly. Any condition that causes scarring or damage to the endometrial-myometrial interface increases this risk. **Why "Previous Abruptio Placenta" is the correct answer:** Abruptio placenta is a clinical event where the placenta prematurely separates from the uterine wall *during* a pregnancy. It is a complication of a current or past pregnancy but does **not** cause permanent structural scarring or thinning of the decidua. Therefore, it is not a recognized risk factor for the abnormal adherence seen in placenta accreta. **Why the other options are incorrect (Risk Factors for Accreta):** * **Previous LSCS (Option A):** This is the **most significant risk factor**. The scar tissue lacks a proper decidual layer. The risk increases exponentially with the number of previous sections (e.g., >60% risk if there is placenta previa and 4+ previous LSCS). * **Previous Curettage (Option B):** Vigorous scraping of the uterine cavity (D&C) can damage the basal endometrium, leading to Asherman syndrome or localized decidual deficiency. * **Previous Myomectomy (Option C):** Any surgery that involves opening the uterine cavity or scarring the myometrium creates a site where the decidua may be absent or defective. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Lower uterine segment (due to poor decidualization). * **Strongest Association:** Previous LSCS + Placenta Previa. * **Nitabuch Layer:** The fibrinoid layer between the decidua basalis and the trophoblast that is **absent** in placenta accreta. * **Management:** The gold standard for confirmed PAS is **Planned Cesarean Hysterectomy**.

Q: What is the typical pH of amniotic fluid in later weeks of gestation?

7.2. **Explanation:** The pH of amniotic fluid is a critical clinical marker used to differentiate it from other vaginal fluids. In the later weeks of gestation, amniotic fluid is **slightly alkaline**, typically ranging between **7.0 and 7.5**, with **7.2** being the most representative value. **Why 7.2 is correct:** Amniotic fluid is primarily composed of fetal urine in the third trimester. Since fetal urine and systemic circulation are slightly alkaline, the resulting fluid maintains a pH above neutral. This alkalinity is the physiological basis for the **Nitrazine test** used to diagnose Premature Rupture of Membranes (PROM). **Analysis of Incorrect Options:** * **A (4.5):** This is the typical **acidic pH of a normal vagina** in a reproductive-age woman (maintained by *Lactobacillus* producing lactic acid). * **B (6.5):** While closer to neutral, this is too acidic for healthy amniotic fluid. However, vaginal secretions mixed with amniotic fluid might show a pH in this range. * **C (7.0):** This is neutral pH. While amniotic fluid can occasionally be 7.0, it is characteristically more alkaline (7.2) in a healthy pregnancy. **High-Yield Clinical Pearls for NEET-PG:** * **Nitrazine Test:** When amniotic fluid (pH 7.0–7.5) leaks into the vagina (pH 4.5–5.5), the Nitrazine paper turns **blue** (indicating a pH > 6.0). * **False Positives in Nitrazine Test:** Presence of blood, semen, soap, or antiseptic solutions (like Savlon/Betadine) can cause a false-positive result as they are also alkaline. * **Fern Test:** This is the gold standard for confirming ROM; it relies on the high sodium chloride content of amniotic fluid crystallizing into a "fern" pattern on a slide.

Q: A pseudogestational sac seen on ultrasonography is suspicious of what condition?

Ectopic pregnancy. ### Explanation **Correct Answer: C. Ectopic pregnancy** A **pseudogestational sac** is a common sonographic pitfall in the diagnosis of early pregnancy. It represents an intra-uterine fluid collection (blood or secretions) surrounded by a single layer of decidua, mimicking a true gestational sac. * **Why it indicates Ectopic Pregnancy:** In an ectopic pregnancy, high levels of hCG stimulate the uterine lining, causing a decidual reaction. This can lead to the accumulation of fluid or blood in the endometrial cavity. Unlike a true gestational sac, a pseudogestational sac is **centrally located** (not eccentric), lacks a **yolk sac**, and does not show the **"Double Decidual Sign"** (the two concentric rings representing the decidua capsularis and decidua parietalis). Its presence in a patient with a positive pregnancy test and no visible intrauterine pregnancy should immediately raise suspicion for an ectopic pregnancy. **Analysis of Incorrect Options:** * **A, B, & D (Missed, Incomplete, and Complete Abortion):** These are forms of intrauterine pregnancies (IUP). While they may show an irregular sac or retained products of conception, they are preceded by a true gestational sac. A pseudogestational sac is specifically a "false" sac associated with an extrauterine (ectopic) pregnancy. **High-Yield Clinical Pearls for NEET-PG:** * **Double Decidual Sign:** The most reliable sign of a true early IUP (usually seen at 5.5–6 weeks). * **Yolk Sac:** Its presence definitively confirms an IUP and rules out a pseudogestational sac. * **Location:** A true gestational sac is typically **eccentric** (embedded in the endometrium), whereas a pseudogestational sac is **central** (within the uterine cavity). * **Discriminatory Zone:** If the serum β-hCG is >1,500–2,000 mIU/mL and no IUP is seen on TVS, ectopic pregnancy must be excluded.

Q: What is the primary method for the antenatal diagnosis of hydrocephalus?

Ultrasound (USG). **Explanation:** **1. Why Ultrasound (USG) is the Correct Answer:** Ultrasound is the **gold standard and primary modality** for screening and diagnosing fetal structural anomalies, including hydrocephalus. It is non-invasive, cost-effective, and lacks ionizing radiation. The diagnosis is typically made by measuring the **atrial width of the lateral ventricles**. A measurement **>10 mm** at any gestational age is considered ventriculomegaly, which may progress to hydrocephalus. USG can also identify the underlying cause, such as Aqueductal Stenosis or Dandy-Walker malformation. **2. Why the Incorrect Options are Wrong:** * **Alpha-fetoprotein (AFP) estimation:** Elevated AFP levels in maternal serum or amniotic fluid are markers for **Neural Tube Defects (NTDs)** like Anencephaly or Spina Bifida, but they do not directly diagnose hydrocephalus. * **Foetoscopy:** This is an invasive endoscopic procedure used for fetal surgery or direct visualization. It is not a screening or primary diagnostic tool for hydrocephalus due to high procedural risks. * **Amniocentesis:** While used to detect chromosomal abnormalities or infections (which may be associated with hydrocephalus), it cannot visualize the ventricular system to provide a structural diagnosis. **3. High-Yield Clinical Pearls for NEET-PG:** * **Normal Atrial Width:** 15 mm. * **Dangling Choroid Sign:** A classic USG finding in fetal hydrocephalus where the choroid plexus falls dependently within the enlarged lateral ventricle. * **Fetal MRI:** Used as an adjunct to USG for better characterization of posterior fossa anomalies or cortical development issues, but it is not the *primary* method.

Question 1

Which of the following sites are the rarest and most common for ectopic pregnancy, respectively?

Accepted Answer

Cervix and ampulla of fallopian tube

Answer

Ovary and ampulla of fallopian tube

Answer

Broad ligament and isthmus of fallopian tube

Answer

Abdomen and isthmus of fallopian tube

Question 2

Amniotic fluid volume in polyhydramnios is more than:

Accepted Answer

2000ml

Answer

500ml

Answer

1000ml

Answer

1500ml

Question 3

Which of the following measures the amount of fetal blood entering maternal circulation?

Accepted Answer

Kleihauer-Betke test

Answer

Singers test

Answer

APT test

Answer

Benedict test

Question 4

Which of the following is NOT considered a high-risk factor for gestational hypertension?

Accepted Answer

Polyhydramnios

Answer

Blood pressure of 150/100 mm Hg

Answer

Gestation age less than 30 weeks

Answer

Intrauterine growth restriction (IUGR)

Question 5

In diabetic pregnancy, which of the following is least common?

Accepted Answer

Caudal regression syndrome

Answer

Anencephaly

Answer

Ventricular septal defect (VSD)

Answer

Spina bifida

Question 6

Which of the following is NOT a common cause of placenta accreta?

Accepted Answer

Previous abruptio placenta

Answer

Previous lower segment caesarean section (LSCS)

Answer

Previous curettage

Answer

Previous myomectomy

Question 7

What is the typical pH of amniotic fluid in later weeks of gestation?

Accepted Answer

7.2

Answer

4.5

Answer

6.5

Answer

7.0

Question 8

A pseudogestational sac seen on ultrasonography is suspicious of what condition?

Accepted Answer

Ectopic pregnancy

Answer

Missed abortion

Answer

Incomplete abortion

Answer

Complete abortion

Question 9

In a pregnant female with BP 150/100 mm Hg, a protein/creatinine ratio of what value suggests the development of pre-eclampsia?

Accepted Answer

>0.30

Answer

>0.20

Answer

<0.20

Answer

<0.30

Question 10

What is the primary method for the antenatal diagnosis of hydrocephalus?

Accepted Answer

Ultrasound (USG)

Answer

Alpha-fetoprotein (AFP) estimation

Answer

Foetoscopy

Answer

Amniocentesis

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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