Maternal-Fetal Medicine Practice Questions

Q: Singer's alkali denaturation test is performed for?

Vasa previa. **Explanation:** The **Singer’s alkali denaturation test** (also known as the Apt test) is used to differentiate between **fetal hemoglobin (HbF)** and **adult hemoglobin (HbA)**. The test relies on the principle that fetal hemoglobin is resistant to denaturation by strong alkalis (like Potassium Hydroxide), whereas adult hemoglobin is not. 1. **Why Vasa Previa is Correct:** In vasa previa, the bleeding originates from the fetal vessels crossing the internal os. When vaginal bleeding occurs, it is critical to determine if the blood is maternal or fetal. In the Singer test, the blood is mixed with 1% KOH; if the solution remains **pink**, it indicates the presence of HbF (fetal blood), confirming the diagnosis of vasa previa. If it turns yellow-brown, it is maternal blood. 2. **Why Incorrect Options are Wrong:** * **Rh Incompatibility:** This is managed by Kleihauer-Betke (KB) test (to quantify feto-maternal hemorrhage) or Indirect Coombs Test, not Singer’s test. * **Abruptio Placenta:** The bleeding here is primarily maternal in origin (retroplacental hemorrhage). * **Preterm Labor:** This is a clinical diagnosis based on uterine contractions and cervical changes; biochemical tests like Fetal Fibronectin (fFN) are used, not hemoglobin denaturation tests. **High-Yield Clinical Pearls for NEET-PG:** * **Apt Test vs. Kleihauer-Betke (KB) Test:** Apt test is a qualitative bedside test for vaginal blood; KB test is a quantitative acid-elution test used on maternal peripheral blood to calculate the dose of Anti-D. * **Vasa Previa Triad:** Rupture of membranes + Painless vaginal bleeding + Fetal bradycardia/distress. * **HbF Resistance:** HbF is resistant to both **alkali** (Singer/Apt test) and **acid** (KB test).

Q: The above shown device is used for:

Non-stress test. ***Non-stress test*** - The **cardiotocograph (CTG)** monitors **fetal heart rate** and **uterine contractions** simultaneously to assess fetal well-being without inducing stress. - **Non-stress test (NST)** evaluates fetal heart rate **accelerations** in response to fetal movements, indicating adequate fetal oxygenation and neurological function. *Gestational age assessment* - Gestational age is determined using **ultrasound biometry** measuring **biparietal diameter**, **head circumference**, and **femur length**. - **CTG** does not provide anatomical measurements required for gestational age calculation. *Fetal arterial Doppler* - **Doppler ultrasound** is used to assess **umbilical artery**, **middle cerebral artery**, and **uterine artery** blood flow patterns. - **CTG** monitors heart rate patterns but does not evaluate **vascular resistance** or blood flow velocities. *Detecting progression of labor* - Labor progression is assessed through **cervical dilation** and **fetal station** via **vaginal examination** and **partograph**. - While **CTG** monitors contractions, it does not measure **cervical changes** or **fetal descent** necessary for labor progression assessment.

Q: After 20 weeks of gestation, what is the main contribution to amniotic fluid?

Fetal urine. **Explanation:** The volume and composition of amniotic fluid change dynamically throughout pregnancy. After **20 weeks of gestation**, the primary source of amniotic fluid is **fetal urine**. **1. Why Fetal Urine is Correct:** By the second trimester (starting around 12 weeks and becoming dominant by 20 weeks), the fetal kidneys are functional. The fetus swallows amniotic fluid, which is absorbed by the gastrointestinal tract and then excreted as urine back into the amniotic sac. At term, a fetus produces approximately 700–1000 mL of urine per day. This recycling process is crucial for maintaining fluid volume and lung development. **2. Why Other Options are Incorrect:** * **Maternal serum (B):** While maternal serum contributes to fluid volume in the *first* trimester via the amnion, its role becomes negligible in the second half of pregnancy. * **Transudate through fetal skin (C):** This is the main source *before* 20 weeks. However, after 20 weeks, the fetal skin undergoes **keratinization**, making it impermeable to water and solutes. * **Transudate across the umbilical cord (D):** This (along with the chorionic plate) provides a minor contribution via the intramembranous pathway but is never the "main" source. **High-Yield Clinical Pearls for NEET-PG:** * **Renal Agenesis (Potter’s Syndrome):** Absence of kidneys leads to severe **oligohydramnios** because urine production is the main fluid source. * **Esophageal Atresia:** Inability of the fetus to swallow fluid leads to **polyhydramnios**. * **Peak Volume:** Amniotic fluid volume peaks at approximately **800 mL at 34 weeks** of gestation before gradually decreasing. * **Amniotic Fluid Index (AFI):** Normal range is 5–24 cm; 24 cm is polyhydramnios.

Q: Hydramnios is complicated by which of the following conditions, EXCEPT?

Post-dated pregnancy. **Explanation:** Hydramnios (Polyhydramnios) is defined as an amniotic fluid index (AFI) > 25 cm or a single deepest pocket (SDP) > 8 cm. It is associated with several maternal and fetal complications due to uterine overdistension. **Why Post-dated pregnancy is the correct answer:** Post-dated pregnancy (prolonged pregnancy) is typically associated with **Oligohydramnios**, not hydramnios. As the pregnancy progresses beyond 40 weeks, placental function declines (placental insufficiency), leading to decreased fetal renal perfusion and reduced fetal urine output, which is the primary source of amniotic fluid in late pregnancy. **Analysis of incorrect options:** * **Placenta Abruptio:** Sudden decompression of the overdistended uterus (e.g., during rupture of membranes) can lead to a shearing effect on the placenta, causing premature separation. * **Pre-eclampsia:** There is a known clinical association between hydramnios and pre-eclampsia (seen in ~25% of cases), likely due to increased uterine tension and placental factors. * **Atonic Hemorrhage:** Overdistension of the uterine muscle fibers by excessive fluid leads to poor uterine contractility (inertia) after delivery, making atonic Postpartum Hemorrhage (PPH) a major risk. **Clinical Pearls for NEET-PG:** * **Most common cause:** Idiopathic (approx. 50-60%). * **Most common fetal anomaly:** Anencephaly (due to lack of swallowing reflex and transudation from exposed meninges). * **Maternal association:** Diabetes mellitus is the most common maternal cause. * **Management:** Therapeutic amniocentesis is indicated if the mother is symptomatic (dyspnea/distress); Indomethacin can be used (before 32 weeks) to decrease fetal urine output.

Q: Abruptio placentae occurs in all except?

Alcoholics. **Explanation:** Abruptio placentae refers to the premature separation of a normally situated placenta from the uterine wall before the birth of the fetus. The etiology is primarily related to vascular compromise or direct trauma. **Why Alcoholics is the correct answer:** While chronic alcohol consumption is associated with Fetal Alcohol Syndrome and intrauterine growth restriction (IUGR), it is **not** a recognized independent risk factor for placental abruption. In contrast, substances like cocaine (a potent vasoconstrictor) are strongly linked to abruption. **Analysis of incorrect options:** * **Smokers:** Smoking causes decidual necrosis and placental hypoperfusion due to the vasoconstrictive effects of nicotine and increased carbon monoxide levels. This doubles the risk of abruption. * **Pregnancy-induced hypertension (PIH):** This is the **most common predisposing factor** for abruption. Chronic hypertension or preeclampsia leads to degenerative changes in the spiral arteries, causing retroplacental hemorrhage. * **Folic acid deficiency:** Deficiency leads to hyperhomocysteinemia, which causes endothelial damage and vascular thrombosis in the placental bed, predisposing the patient to premature separation. **Clinical Pearls for NEET-PG:** * **Most common cause:** Maternal hypertension (PIH/Chronic). * **Most common cause of DIC in pregnancy:** Abruptio placentae. * **Classic presentation:** Painful vaginal bleeding (revealed), uterine tenderness, and increased uterine tone (woody hard uterus). * **Couvelaire Uterus:** A complication where blood extravasates into the myometrium, seen during C-section as a purplish/bluish discoloration. * **Other risk factors:** Sudden uterine decompression (e.g., rupture of membranes in polyhydramnios), trauma, and short umbilical cord.

Q: Magnesium sulphate toxicity includes all of the following EXCEPT?

Oliguria. Magnesium sulphate ($MgSO_4$) is the drug of choice for seizure prophylaxis in pre-eclampsia and control in eclampsia [1]. It acts as a CNS depressant and neuromuscular blocker. The key to understanding its toxicity lies in the **sequential disappearance of physiological functions** as serum magnesium levels rise. ### Why Oliguria is the Correct Answer **Oliguria is a contraindication to/risk factor for toxicity, not a sign of toxicity itself.** $MgSO_4$ is excreted almost exclusively by the kidneys. If a patient has oliguria (urine output <30 ml/hr), the drug accumulates rapidly, leading to toxic levels [1]. Therefore, monitoring urine output is mandatory *during* administration to prevent toxicity, but the toxicity itself does not cause decreased urine output. ### Explanation of Incorrect Options (Signs of Toxicity) As serum levels increase (Normal therapeutic range: 4–7 mEq/L), toxicity manifests in this specific order: * **Loss of Patellar Reflex (8–10 mEq/L):** This is the **earliest clinical sign** of toxicity [1]. The knee-jerk reflex disappears due to the blockade of neuromuscular transmission [2]. * **Respiratory Depression (12–15 mEq/L):** Higher levels lead to paralysis of respiratory muscles [1]. * **Cardiac Arrest (>25 mEq/L):** Extreme levels cause direct myocardial depression and cardiac standstill [1]. ### High-Yield Clinical Pearls for NEET-PG * **Monitoring Parameters:** Always check for (1) Presence of patellar reflex, (2) Respiratory rate >12/min, and (3) Urine output >30 ml/hr (or 100 ml/4 hrs) [1]. * **Antidote:** 10 ml of **10% Calcium Gluconate** IV (administered slowly over 10 minutes) [1]. * **Therapeutic Level:** 4–7 mEq/L (or 4.8–8.4 mg/dL). * **Pritchard Regimen:** Total loading dose is 14g (4g IV + 10g IM). Maintenance is 5g IM every 4 hours in alternating buttocks.

Question 1

A 30-year-old G1P1001 patient presents at 37 weeks gestational age with a breech presentation. The cervix is 50% effaced and 1-2 cm dilated. The estimated fetal weight is 7 lbs. The patient is offered all the following management plans EXCEPT:

Accepted Answer

Send the patient to labor and delivery immediately for an emergency Cesarean section.

Answer

Allow the patient to undergo a vaginal breech delivery when she goes into labor.

Answer

Schedule a Cesarean section at or after 39 weeks gestation.

Answer

Schedule an external cephalic version in the next few days.

Question 2

A pregnant woman at 39 weeks gestation with a singleton fetus in cephalic presentation develops chickenpox. She has no other pregnancy complications. What is the best method to prevent neonatal infection?

Accepted Answer

Continue the pregnancy for at least one week.

Answer

Administer varicella zoster immune globulin (VZIG) to the neonate soon after birth.

Answer

Administer varicella zoster vaccine to the neonate soon after birth.

Answer

Induce labor immediately.

Question 3

Singer's alkali denaturation test is performed for?

Accepted Answer

Vasa previa

Answer

Rh incompatibility

Answer

Abruptio placenta

Answer

Preterm labor

Question 4

The above shown device is used for:

Accepted Answer

Non-stress test

Answer

Gestational age assessment

Answer

Fetal arterial Doppler

Answer

Detecting progression of labor

Question 5

After 20 weeks of gestation, what is the main contribution to amniotic fluid?

Accepted Answer

Fetal urine

Answer

Maternal serum filtered through the placenta

Answer

Transudate of fetal plasma through fetal skin

Answer

Transudate across the umbilical cord

Question 6

Hydramnios is complicated by which of the following conditions, EXCEPT?

Accepted Answer

Post-dated pregnancy

Answer

Placenta abruptio

Answer

Pre-eclampsia

Answer

Atonic Hemorrhage

Question 7

Abruptio placentae occurs in all except?

Accepted Answer

Alcoholics

Answer

Smokers

Answer

Pregnancy-induced hypertension

Answer

Folic acid deficiency

Question 8

Magnesium sulphate toxicity includes all of the following EXCEPT?

Accepted Answer

Oliguria

Answer

Loss of patellar reflex

Answer

Respiratory depression

Answer

Cardiac arrest

Question 9

All of the following are true about SLE in pregnancy except?

Accepted Answer

Increased anti-Ro and anti-La antibodies imply a low risk for congenital heart block.

Answer

Corticosteroids can be continued during pregnancy.

Answer

Recurrent abortions can be a manifestation of SLE in pregnancy.

Answer

The disease activity may worsen during pregnancy.

Question 10

Which of the following is NOT a risk factor for preterm delivery?

Accepted Answer

Absence of fetal fibronectin at less than 37 weeks gestation

Answer

Previous history of preterm delivery

Answer

Asymptomatic cervical dilatation

Answer

Chlamydial infection of the genital tract

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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