Maternal-Fetal Medicine Practice Questions

Q: What is the pathognomonic feature of abdominal pregnancy?

Fetus appears lateral to the lumbar spine on X-ray. **Explanation:** Abdominal pregnancy is a rare but serious form of ectopic pregnancy where the fetus develops within the peritoneal cavity. **Why Option A is correct:** The pathognomonic radiological sign of an abdominal pregnancy is the **fetus appearing lateral to or overlapping the maternal lumbar spine** on a lateral X-ray (the **"Spalding’s Sign"** is different; this is specifically about fetal position relative to the spine). In a normal intrauterine pregnancy, the thick muscular wall of the uterus keeps the fetus centered and anterior to the spine. In an abdominal pregnancy, the lack of a uterine wall allows the fetus to fall posteriorly or laterally, often overlapping the maternal vertebrae on a lateral view. **Analysis of Incorrect Options:** * **B. Small uterus:** While the uterus is indeed smaller than the period of gestation (as it is empty), this is a common finding in all ectopic pregnancies and is not pathognomonic. * **C. Fetus easily palpable:** While "fetal parts felt easily" is a classic clinical sign due to the absence of the uterine wall, it is subjective and can be confused with a very thin uterine wall or a ruptured uterus. * **D. Positive pregnancy test:** This only confirms pregnancy, not the location. **NEET-PG High-Yield Pearls:** * **Clinical Sign:** Failure of the uterus to contract after oxytocin administration (since the fetus is extrauterine). * **Diagnosis:** Ultrasound is the primary modality, but **MRI** is the gold standard for assessing placental attachment to abdominal organs. * **Management:** The placenta is usually left in situ (if attached to vital organs) to avoid massive hemorrhage; methotrexate may be used postoperatively to accelerate its involution.

Q: Which component of the trophoblast does not invade spiral arterioles?

Interstitial trophoblast. **Explanation:** The process of placentation involves the remodeling of maternal spiral arterioles to ensure a high-flow, low-resistance blood supply to the fetus. This is mediated by specific subsets of trophoblasts. **Why Option D is Correct:** The **Interstitial trophoblast** is a subtype of extravillous trophoblast that invades the **decidua and the inner third of the myometrium**. Its primary role is to anchor the placenta and prepare the uterine environment; however, it moves through the stroma and **does not enter or invade the lumen of the spiral arterioles**. **Why the other options are incorrect:** * **Extravillous trophoblast (A):** This is a broad category that includes both interstitial and endovascular trophoblasts. Since one of its subtypes (endovascular) specifically invades the arterioles, this option is less precise than D. * **Endovascular trophoblast (B):** This is the specific subset that **invades the spiral arterioles**. It replaces the maternal endothelial lining and destroys the muscular/elastic tissue of the vessel wall, converting them into large-diameter conduits. * **Tertiary villus (C):** This is a structural unit of the placenta containing fetal capillaries. While it is involved in exchange, the question specifically asks about the cellular component responsible for arteriolar invasion. **High-Yield NEET-PG Pearls:** * **Trophoblast Differentiation:** Cytotrophoblasts (inner layer) differentiate into Syncytiotrophoblasts (outer layer, produces hCG) and Extravillous trophoblasts (invasive). * **Spiral Arteriolar Remodeling:** Failure of endovascular trophoblast invasion is the primary pathophysiology behind **Pre-eclampsia** and **Fetal Growth Restriction (FGR)**. * **Waves of Invasion:** The first wave (decidua) occurs at 6–10 weeks; the second wave (myometrium) occurs at 16–20 weeks. Failure of the second wave is linked to hypertensive disorders of pregnancy.

Q: Non-immune hydrops fetalis is seen in which of the following conditions?

Alpha thalassemia major. **Explanation:** **Hydrops Fetalis** is defined as the abnormal accumulation of fluid in two or more fetal compartments (e.g., ascites, pleural effusion, pericardial effusion, or skin edema). It is categorized into **Immune** (due to maternal antibodies) and **Non-Immune (NIHF)**, which now accounts for ~90% of cases. **Why Alpha Thalassemia Major is correct:** Alpha thalassemia major (Hb Bart’s; genotype --/--) is the most common cause of NIHF in Southeast Asian populations. In this condition, the absence of alpha-globin chains leads to the formation of gamma-tetramers (Hb Bart’s). These have an extremely high affinity for oxygen, failing to release it to fetal tissues. This causes **severe tissue hypoxia**, high-output cardiac failure, and subsequent hydrops. **Analysis of Incorrect Options:** * **B. Rh Incompatibility:** This is the classic cause of **Immune Hydrops Fetalis**. It occurs when a sensitized Rh-negative mother carries an Rh-positive fetus, leading to erythroblastosis fetalis. * **C. Bilateral Renal Agenesis:** This condition leads to **Oligohydramnios** (Potter sequence) due to lack of fetal urine production. It does not typically cause fluid accumulation or hydrops. * **D. Maternal Rubella:** While TORCH infections (like CMV, Syphilis, and Parvovirus B19) are major causes of NIHF, Rubella is more commonly associated with **Congenital Rubella Syndrome** (cataracts, PDA, deafness) rather than hydrops. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of NIHF worldwide:** Cardiovascular anomalies. * **Most common infectious cause of NIHF:** Parvovirus B19 (targets erythrocyte precursors leading to aplastic anemia). * **Chromosomal association:** Turner Syndrome (45, XO) is the most common chromosomal cause of NIHF (often presenting with cystic hygroma). * **Diagnosis:** Ultrasound is the gold standard; look for "Mirror Syndrome" (maternal edema mimicking fetal hydrops).

Q: What is the most common type of monozygotic twin pregnancy based on the timing of cell division between the 4th and 8th day?

Monochorionic diamniotic twins. **Explanation:** The classification of monozygotic (identical) twins depends entirely on the **timing of the division** of the fertilized ovum. 1. **Monochorionic Diamniotic (MCDA) Twins (Correct Answer):** This occurs when division happens between **days 4 and 8** post-fertilization (at the blastocyst stage). By this time, the outer layer (trophoblast) has already differentiated, but the inner cell mass has not. This results in twins sharing one placenta (monochorionic) but having separate amniotic sacs (diamniotic). This is the **most common type of monozygotic pregnancy**, accounting for approximately 70–75% of cases. 2. **Dichorionic Diamniotic (DCDA) Twins (Option D):** Division occurs early, between **days 1 and 3** (at the morula stage). Since division happens before any differentiation, each twin develops its own placenta and amniotic sac. 3. **Monochorionic Monoamniotic (MCMA) Twins (Option B):** Division occurs late, between **days 8 and 13**. By this stage, the amniotic sac has already formed, so the twins share both the placenta and the sac. 4. **Conjoined (Siamese) Twins (Option A):** Division occurs very late, **after day 13** (at the embryonic disc stage), resulting in incomplete separation. **High-Yield NEET-PG Pearls:** * **Rule of 4s:** Remember the timeline in multiples of 4: 0–4 days (DCDA), 4–8 days (MCDA), 8–12 days (MCMA), >13 days (Conjoined). * **T-sign vs. Lambda sign:** On ultrasound, MCDA twins show a **"T-sign"** (thin membrane), while DCDA twins show a **"Lambda (λ) or Twin-peak sign"** (thick membrane). * **Risk:** MCDA twins are at unique risk for **Twin-to-Twin Transfusion Syndrome (TTTS)** due to vascular anastomoses in the shared placenta.

Q: Which among the following drugs is used in the management of ectopic pregnancy?

Methotrexate. **Explanation:** The primary goal in the medical management of ectopic pregnancy is to arrest the growth of the trophoblastic tissue. **1. Why Methotrexate is correct:** **Methotrexate (MTX)** is a folic acid antagonist that inhibits the enzyme **dihydrofolate reductase**. This action prevents the synthesis of purines and pyrimidines, thereby inhibiting DNA synthesis and cell replication. Since trophoblastic cells in an ectopic pregnancy are rapidly dividing, they are highly sensitive to MTX. It is the drug of choice for hemodynamically stable patients with unruptured ectopic pregnancies who meet specific criteria (e.g., low baseline hCG levels, absence of fetal heart activity). **2. Why other options are incorrect:** * **Mifepristone:** A progesterone receptor antagonist used primarily for medical abortion of intrauterine pregnancies. While it can be used as an adjunct, it is not the primary treatment for ectopic pregnancy. * **Misoprostol:** A PGE1 analogue used to induce uterine contractions for cervical ripening or evacuation of the uterus in miscarriages. It has no effect on extrauterine trophoblastic tissue. * **Oxytocin:** A hormone used to induce labor or control postpartum hemorrhage by causing uterine contractions. It is ineffective in treating ectopic pregnancies. **High-Yield Clinical Pearls for NEET-PG:** * **Ideal Candidate for MTX:** Hemodynamically stable, hCG < 5000 mIU/mL, ectopic mass < 3.5–4 cm, and no visible fetal cardiac activity. * **Dose:** Most common regimen is a single intramuscular dose of **50 mg/m²**. * **Contraindications:** Ruptured ectopic pregnancy (most important), breastfeeding, immunodeficiency, or significant hepatic/renal dysfunction. * **Monitoring:** Success is defined by a **≥15% decline** in hCG levels between Day 4 and Day 7 after administration.

Q: What is the recommended dose of betamethasone for prenatal administration to prevent respiratory distress syndrome?

12 mg every 24 hours. **Explanation:** The administration of Antenatal Corticosteroids (ACS) is a cornerstone in the management of preterm labor (24 to 34 weeks) to accelerate fetal lung maturity and reduce the incidence of Respiratory Distress Syndrome (RDS), Intraventricular Hemorrhage (IVH), and Necrotizing Enterocolitis (NEC). **Why Option B is Correct:** The standard, evidence-based regimen for **Betamethasone** is **12 mg intramuscularly (IM) given in two doses, 24 hours apart** (Total dose: 24 mg). This schedule ensures optimal induction of surfactant production by Type II pneumocytes in the fetal lungs. **Analysis of Incorrect Options:** * **Option A & D:** 6 mg and 4 mg are sub-therapeutic doses for fetal lung maturity. * **Option C:** 6 mg every 12 hours for 4 doses (Total 24 mg) is the standard regimen for **Dexamethasone**, not Betamethasone. While the total dose is the same, the dosing interval and individual dose amount differ between the two drugs. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Betamethasone is often preferred over Dexamethasone because it is associated with a lower risk of periventricular leukomalacia. * **Window of Efficacy:** The maximum benefit is seen if delivery occurs between **24 hours and 7 days** after the first dose. * **Mechanism:** Corticosteroids induce the maturation of Type II pneumocytes and stimulate the synthesis and release of **surfactant** into the alveolar spaces. * **Rescue Dose:** A single "rescue course" can be considered if the initial course was given >7 days ago and the patient is still <34 weeks pregnant with an imminent risk of delivery.

Q: Which virus is responsible for non-immune hydrops fetalis?

Parvovirus. **Explanation:** **Parvovirus B19** is the most common viral cause of non-immune hydrops fetalis (NIHF). The virus specifically targets and destroys **erythroid progenitor cells** in the fetal bone marrow by binding to the P-antigen. This leads to severe fetal anemia, which triggers high-output cardiac failure, hepatic congestion, and a decrease in oncotic pressure, ultimately resulting in generalized fetal edema (hydrops). **Analysis of Options:** * **Option D (Parvovirus):** Correct. It causes transient aplastic crisis in the fetus. On ultrasound, this may present with increased Peak Systolic Velocity (PSV) in the Middle Cerebral Artery (MCA), indicating anemia. * **Option A (Cytomegalovirus):** While CMV is the most common congenital infection, it typically presents with intracranial calcifications (periventricular), microcephaly, and IUGR rather than hydrops. * **Option B (Herpes Simplex Virus):** Neonatal HSV is usually acquired during delivery (vertical transmission). Congenital HSV is rare and typically presents with skin vesicles, eye defects, and chorioretinitis. * **Option C (Hepatitis B Virus):** HBV does not cause structural malformations or hydrops; the primary concern is the high risk of chronic carrier status in the neonate if not treated with immunoprophylaxis at birth. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnosis:** Maternal infection is confirmed by IgM antibodies; fetal infection is confirmed by PCR of amniotic fluid. * **Management:** If hydrops is detected and fetal anemia is confirmed (via MCA-PSV), the treatment of choice is **Intrauterine Blood Transfusion (IUT)**. * **Spontaneous Resolution:** Many cases of Parvovirus-induced hydrops can resolve spontaneously if the anemia is not critical. * **Mirror Syndrome:** A rare complication where the mother "mirrors" the fetal hydrops, developing edema and preeclampsia-like symptoms.

Q: Which of the following investigations is BEST used for placental localization?

Ultrasonography. **Explanation:** **Ultrasonography (USG)** is the gold standard and the investigation of choice for placental localization. It is preferred because it is non-invasive, cost-effective, lacks ionizing radiation, and provides high accuracy (nearly 95-98%). Transvaginal Sonography (TVS) is considered superior to Transabdominal Sonography (TAS) for diagnosing placenta previa, as it allows for better visualization of the internal os and the lower placental edge without the interference of maternal obesity or a full bladder. **Why other options are incorrect:** * **X-ray (Soft tissue placentography):** Historically used to identify the placental shadow, but it is now obsolete due to low sensitivity and the risks of fetal radiation exposure. * **Amniography:** This invasive procedure involves injecting radio-opaque dye into the amniotic sac. It is outdated and carries significant risks, such as infection, premature rupture of membranes, and fetal injury. * **Clinical Examination:** Digital vaginal examination (the "Double Setup" examination) is contraindicated in suspected placenta previa unless performed in an operating theater, as it can provoke life-threatening hemorrhage. **High-Yield NEET-PG Pearls:** * **Investigation of Choice:** Transvaginal Ultrasound (TVS) is safer and more accurate than TAS for placental localization. * **MRI:** Reserved for cases of suspected **Placenta Accreta Spectrum (PAS)** where USG is inconclusive. * **Placental Migration:** The phenomenon where the placenta appears to move away from the internal os as the lower uterine segment develops; hence, a definitive diagnosis of placenta previa is usually made after 28 weeks.

Q: Supine hypotension is characteristic of which trimester of pregnancy?

Third trimester. **Explanation:** The correct answer is **C. Third trimester**. **1. Underlying Medical Concept:** Supine hypotension, also known as **Supine Hypotensive Syndrome** or **Aortocaval Compression**, occurs when the gravid uterus compresses the **Inferior Vena Cava (IVC)** and, to a lesser extent, the aorta when the mother lies flat on her back. This compression reduces venous return to the heart (preload), leading to a fall in cardiac output and a subsequent drop in maternal blood pressure. This phenomenon is most prominent in the **third trimester** because the uterus has reached a sufficient size and weight (usually after 28 weeks) to exert significant mechanical pressure on the retroperitoneal vessels. **2. Analysis of Incorrect Options:** * **A & B (First and Second Trimesters):** In the first trimester, the uterus is a pelvic organ. In the early second trimester, though it becomes an abdominal organ, it is not heavy enough to cause significant IVC compression. * **D (Twin Pregnancy):** While supine hypotension is more severe in twin pregnancies due to increased uterine volume, it is not a "trimester." The question asks for the specific period of pregnancy where this is characteristic; even in twins, the effect is most pronounced during the third trimester. **3. NEET-PG High-Yield Pearls:** * **Clinical Presentation:** Maternal dizziness, pallor, tachycardia, and nausea when supine. * **Management:** Immediate relief is obtained by the **Left Lateral Position**, which shifts the uterus off the IVC. * **Fetal Impact:** Prolonged supine hypotension can lead to reduced uteroplacental perfusion and fetal distress. * **Surgical Note:** During Cesarean sections, a "wedge" is placed under the right hip to tilt the patient 15° to the left to prevent this syndrome during anesthesia.

Question 1

What is the pathognomonic feature of abdominal pregnancy?

Accepted Answer

Fetus appears lateral to the lumbar spine on X-ray

Answer

Small uterus

Answer

Fetus easily palpable

Answer

Positive pregnancy test

Question 2

Which of the following pregnancy complications is associated with polycythemia vera?

Accepted Answer

Stillbirth

Answer

Coagulopathy

Answer

Placental abruption

Answer

Placenta previa

Question 3

Which component of the trophoblast does not invade spiral arterioles?

Accepted Answer

Interstitial trophoblast

Answer

Extravillous trophoblast

Answer

Endovascular trophoblast

Answer

Tertiary villus

Question 4

Non-immune hydrops fetalis is seen in which of the following conditions?

Accepted Answer

Alpha thalassemia major

Answer

Rh incompatibility

Answer

Bilateral renal agenesis

Answer

Maternal rubella

Question 5

What is the most common type of monozygotic twin pregnancy based on the timing of cell division between the 4th and 8th day?

Accepted Answer

Monochorionic diamniotic twins

Answer

Siamese presentation of monochorionic monoamniotic twins

Answer

Monochorionic monoamniotic twins

Answer

Dichorionic diamniotic twins

Question 6

Which among the following drugs is used in the management of ectopic pregnancy?

Accepted Answer

Methotrexate

Answer

Mifepristone

Answer

Misoprostol

Answer

Oxytocin

Question 7

What is the recommended dose of betamethasone for prenatal administration to prevent respiratory distress syndrome?

Accepted Answer

12 mg every 24 hours

Answer

6 mg

Answer

6 mg every 12 hours

Answer

4 mg

Question 8

Which virus is responsible for non-immune hydrops fetalis?

Accepted Answer

Parvovirus

Answer

Cytomegalovirus

Answer

Herpes simplex virus

Answer

Hepatitis B virus

Question 9

Which of the following investigations is BEST used for placental localization?

Accepted Answer

Ultrasonography

Answer

X-ray

Answer

Amniography

Answer

Clinical examination

Question 10

Supine hypotension is characteristic of which trimester of pregnancy?

Accepted Answer

Third trimester

Answer

First trimester

Answer

Second trimester

Answer

Twin pregnancy

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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