Maternal-Fetal Medicine — MCQs

A 19-year-old woman presents to the emergency department reporting that she fainted at work earlier in the day. She has mild vaginal bleeding and her abdomen is diffusely tender and distended. She also complains of shoulder and abdominal pain. Her vital signs show temperature 97.6°F (36.4°C), pulse 120/min, and blood pressure 96/50 mmHg. To confirm the diagnosis suggested by the available clinical data, the best initial diagnostic procedure is

Q1086

Risk for postnatal urinary abnormality is severe if Renal pelvic dilatation is ----- in third trimester?

Q1087

Which maternal antibody is responsible for heart block in a baby born to a mother suffering from SLE?

Q1088

Soft markers on ultrasonography are helpful in diagnosing?

Q1089

A lady with 10-12 wks pregnancy develops acute retention of urine. The likely cause is-

Q1090

Umbilical artery Doppler is done to assess

Maternal-Fetal Medicine Indian Medical PG Practice Questions and MCQs

Question 1081: In a patient with ectopic tubal pregnancy which is the earliest to rupture?

A. Infundibulum
B. Isthmus (Correct Answer)
C. Ampulla
D. Interstitial

Explanation: ***Isthmus*** - The **isthmus** is the **narrowest part** of the fallopian tube with the **least distensibility** and thin muscular wall. - Due to its limited capacity to accommodate the growing pregnancy, ectopic pregnancies in the isthmus rupture **earliest**, typically between **6-8 weeks of gestation**. - Rupture is often severe due to the narrow lumen and limited ability to expand. *Ampulla* - The **ampulla** is the most common site for ectopic pregnancies (approximately **70%** of cases). - It is wider and more distensible than the isthmus, allowing the pregnancy to grow for a longer period. - Rupture typically occurs **later**, between **8-12 weeks of gestation**. *Interstitial* - The **interstitial** (or cornual) portion is located within the **uterine wall**, surrounded by myometrium and rich vascular supply. - This location allows significant distensibility, so rupture occurs **latest** among tubal sites, typically at **12-16 weeks of gestation**. - When rupture occurs, it is **most catastrophic** with severe hemorrhage and highest risk of **maternal morbidity and mortality** due to the vascular supply. *Infundibulum* - Ectopic pregnancies in the **infundibulum** or fimbrial end are very rare. - Due to the wide opening, these pregnancies typically present as **tubal abortion** through the fimbria rather than rupture. - The area is less muscular, making contained rupture uncommon.

Question 1082: Singer's alkali denaturation test is used to differentiate

A. Fetal blood from maternal blood (Correct Answer)
B. Arterial blood from venous blood
C. Oxygenated blood from deoxygenated blood
D. Adult hemoglobin from sickle cell hemoglobin

Explanation: ***Fetal blood from maternal blood*** - Singer's alkali denaturation test is specifically designed to differentiate **fetal hemoglobin (HbF)** from **adult hemoglobin (HbA)** based on their resistance to alkali denaturation. - **Fetal hemoglobin is resistant to alkali denaturation**, while adult hemoglobin is rapidly denatured under alkaline conditions (pH 12.5-13). - This test is clinically useful in **obstetric practice** to detect fetal blood in maternal circulation, assess fetal-maternal hemorrhage, and evaluate conditions like **hereditary persistence of fetal hemoglobin (HPFH)**. - The principle: When blood is treated with strong alkali (NaOH), HbA is converted to alkaline hematin (brown), while HbF remains pink due to its stability. *Oxygenated blood from deoxygenated blood* - Singer's test does NOT differentiate oxygenated from deoxygenated blood. - This differentiation is based on **blood gas analysis** (pO2, pCO2, oxygen saturation) or visual inspection (bright red vs dark red color). - The test focuses on hemoglobin type stability, not oxygenation status. *Arterial blood from venous blood* - Arterial vs venous blood differentiation relies on **blood gas analysis**, pH measurements, and oxygen content. - Singer's alkali denaturation test is not used for this purpose as it tests hemoglobin structural resistance, not blood origin or oxygenation. *Adult hemoglobin from sickle cell hemoglobin* - **Hemoglobin electrophoresis** and **sickle solubility test** (dithionite test) are the standard methods to detect **HbS** in sickle cell disease. - While Singer's test can detect abnormal hemoglobins with alkali resistance, it is not the primary diagnostic tool for differentiating HbA from HbS.

Question 1083: Which of the following statements is true regarding cerclage?

A. Timing of surgery is between 12 → 14 weeks gestation.
B. No need of antibiotic prophylaxis as membranes not ruptured.
C. Prolapsing membranes can be reduced with Trendelenburg positioning and bladder filling prior to cerclage placement. (Correct Answer)
D. Shirodkar procedure is most often selected.

Explanation: ***Prolapsing membranes can be reduced with Trendelenburg positioning and bladder filling prior to cerclage placement.*** - **Trendelenburg positioning** and **bladder filling** help to displace the gravid uterus superiorly, reducing pressure on the cervix and allowing the membranes to fall back into the uterine cavity. - This technique is crucial for successful cerclage placement when there is **cervical effacement or dilation with prolapsed membranes**, preventing their accidental rupture during the procedure. *Timing of surgery is between 12 → 14 weeks gestation.* - While this timeframe overlaps with cerclage placement, the most common timing for an indicated cerclage is typically between **13-16 weeks gestation**, or even up to 23 weeks depending on the indication. - The optimal window balances the period after **spontaneous miscarriage risk decreases** (>12-13 weeks) and before significant cervical changes occur. *No need of antibiotic prophylaxis as membranes not ruptured.* - **Antibiotic prophylaxis is generally recommended** for cerclage procedures, even in the absence of ruptured membranes, to reduce the risk of **postoperative infection**. - The surgical manipulation of the cervix can potentially introduce bacteria into the sterile uterine environment, which could lead to chorioamnionitis or preterm labor. *Shirodkar procedure is most often selected.* - The **McDonald cerclage** is the most common and widely preferred surgical technique for cervical cerclage due to its relative simplicity and effectiveness. - The Shirodkar procedure is generally reserved for specific indications where the McDonald technique is deemed insufficient, or in cases of **anatomical anomaly** or failed previous McDonald cerclage.

Question 1084: A 30-year-old lady develops retention of urine in the 2nd trimester. The most probable cause is:

A. Bladder neck obstruction due to ovarian cyst
B. Fibroid uterus
C. Retroverted uterus (Correct Answer)
D. Neurogenic bladder

Explanation: ***Retroverted uterus*** - A **retroverted uterus** in the second trimester can become entrapped in the sacral hollow, obstructing the bladder neck as the uterus enlarges. - This anatomical position prevents the uterus from rising into the abdomen, leading to **urinary retention**. *Bladder neck obstruction due to ovarian cyst* - While an **ovarian cyst** *could* potentially cause bladder neck obstruction, it is a less common cause of urinary retention in the second trimester compared to an entrapped retroverted uterus. - The presence of an ovarian cyst specifically causing significant obstruction would usually present with additional symptoms related to the cyst itself. *Fibroid uterus* - **Uterine fibroids** can cause various obstetric complications, but significant urinary retention due to bladder neck obstruction in the second trimester is not a typical presentation. - Large fibroids may put pressure on the bladder, but direct obstruction leading to retention is less common than with an entrapped retroverted uterus. *Neurogenic bladder* - A **neurogenic bladder** is a disorder of bladder function due to neurological damage, and its onset would likely predate or not specifically coincide with the second trimester of pregnancy. - This condition involves issues with nerve signals to the bladder, which would not typically manifest acutely as urinary retention solely due to pregnancy unless there was an underlying neurological condition.

Question 1085: A 19-year-old woman presents to the emergency department reporting that she fainted at work earlier in the day. She has mild vaginal bleeding and her abdomen is diffusely tender and distended. She also complains of shoulder and abdominal pain. Her vital signs show temperature 97.6°F (36.4°C), pulse 120/min, and blood pressure 96/50 mmHg. To confirm the diagnosis suggested by the available clinical data, the best initial diagnostic procedure is

A. Serum beta-hCG levels
B. Transvaginal ultrasound (Correct Answer)
C. FAST (Focused Assessment with Sonography in Trauma)
D. Diagnostic laparoscopy

Explanation: ***Transvaginal ultrasound*** - This patient presents with **ruptured ectopic pregnancy**: hemodynamic instability (syncope, tachycardia, hypotension), vaginal bleeding, abdominal pain with peritoneal signs, and **Kehr's sign** (shoulder pain from diaphragmatic irritation by blood). - In a **hemodynamically unstable patient** with suspected ruptured ectopic pregnancy, **transvaginal ultrasound** is the best initial diagnostic procedure because it: - Rapidly confirms or rules out **intrauterine pregnancy** - Detects **free fluid (blood) in the pelvis** indicating rupture - Visualizes **adnexal masses** suggestive of ectopic pregnancy - Can be performed quickly at bedside - Directly guides the decision for **emergency surgery** - While beta-hCG should be sent concurrently, ultrasound findings take precedence in guiding immediate management in unstable patients. *Serum beta-hCG levels* - Beta-hCG is essential for confirming pregnancy and is the **initial test in stable patients** with suspected ectopic pregnancy. - However, in this **hemodynamically unstable patient**, waiting for beta-hCG results delays definitive diagnosis and treatment. - Beta-hCG should be sent but **does not replace imaging** when rupture is suspected - a positive hCG only confirms pregnancy, not its location or rupture status. - Management decisions in unstable patients are based on **imaging findings**, not hCG levels alone. *Diagnostic laparoscopy* - This is both a **diagnostic and therapeutic procedure** for ectopic pregnancy. - While it may be needed for definitive treatment, it is **invasive** and requires operating room setup. - **Ultrasound should be performed first** to confirm the diagnosis and guide surgical planning, unless the patient is in extremis requiring immediate laparotomy. *FAST (Focused Assessment with Sonography in Trauma)* - FAST can detect **free intraperitoneal fluid** and may be useful in identifying hemoperitoneum. - However, **transvaginal ultrasound is superior** in this obstetric emergency because it provides more specific information about pregnancy location, adnexal pathology, and pelvic free fluid. - FAST does not adequately visualize pelvic structures or confirm/exclude intrauterine pregnancy.

Question 1086: Risk for postnatal urinary abnormality is severe if Renal pelvic dilatation is ----- in third trimester?

A. 7 to < 9mm
B. 9 to <= 15mm
C. 4 to < 7mm
D. > 15mm (Correct Answer)

Explanation: ***> 15mm*** - A renal pelvic dilatation **greater than 15mm** in the third trimester is classified as **severe hydronephrosis**, indicating a high risk for significant postnatal urinary abnormalities. - This degree of dilatation often suggests an underlying **obstructive uropathy** or **vesicoureteral reflux (VUR)** that may require surgical intervention. *9 to <= 15mm* - This range typically indicates **moderate hydronephrosis**, which carries an intermediate risk for postnatal urinary issues compared to severe cases. - While follow-up is necessary, the likelihood of requiring surgical intervention is lower than with severe dilatation. *7 to < 9mm* - This range is usually considered **mild hydronephrosis**, and many cases resolve spontaneously after birth. - The risk of significant postnatal urinary abnormalities is relatively low, though monitoring is still recommended. *4 to < 7mm* - In the third trimester, a renal pelvic dilatation in this range is often considered **physiologic or very mild**, with a minimal risk of postnatal pathology. - Most cases will resolve without intervention, and significant urinary abnormalities are rare.

Question 1087: Which maternal antibody is responsible for heart block in a baby born to a mother suffering from SLE?

A. Anti-Sm antibody
B. Anti-RNP antibody
C. Anti-Ro antibody (Correct Answer)
D. Anti-dsDNA antibody

Explanation: ***Anti-Ro antibody*** - **Anti-Ro (SS-A)** antibodies are strongly associated with **neonatal lupus** and its most severe manifestation, congenital heart block. - These antibodies can cross the placenta and target fetal cardiac tissue, leading to irreversible damage to the **atrioventricular node**. *Anti-Sm antibody* - **Anti-Sm (Smith)** antibodies are highly specific for **Systemic Lupus Erythematosus (SLE)** and are associated with severe disease activity, but not directly linked to congenital heart block. - They target components of the **spliceosome** and are considered a diagnostic marker for SLE. *Anti-RNP antibody* - **Anti-RNP (ribonucleoprotein)** antibodies are associated with **Mixed Connective Tissue Disease (MCTD)** and can be present in SLE, but they are not the primary cause of neonatal lupus or congenital heart block. - High titers of anti-RNP antibodies are often linked to features like **Raynaud's phenomenon**, **myositis**, and **sclerodactyly**. *Anti-dsDNA antibody* - **Anti-dsDNA (double-stranded DNA)** antibodies are highly specific for **SLE** and correlate with disease activity, particularly with **lupus nephritis**. - While important in SLE diagnosis and monitoring, they are not directly implicated in the pathogenesis of **congenital heart block** in neonates.

Question 1088: Soft markers on ultrasonography are helpful in diagnosing?

A. Site of pregnancy
B. Fetal size
C. Fetal age
D. Chromosomal anomalies (Correct Answer)

Explanation: ***Chromosomal anomalies*** - **Soft markers** are sonographic findings that, while not structural anomalies themselves, are **statistically associated** with an increased risk of chromosomal abnormalities, particularly **Down syndrome (Trisomy 21)** and other aneuploidies. - Common examples include **nuchal fold thickening**, **echogenic intracardiac focus**, **choroid plexus cysts**, **pyelectasis**, **shortened long bones**, and **echogenic bowel**. - These markers help identify pregnancies at higher risk for chromosomal anomalies and guide decisions about further diagnostic testing (e.g., amniocentesis, NIPT). *Site of pregnancy* - The site of pregnancy (intrauterine vs. ectopic) is determined by direct visualization of the **gestational sac** and **embryo** within or outside the uterine cavity. - Soft markers do not indicate pregnancy location. *Fetal size* - **Fetal size** is assessed through biometric measurements: **crown-rump length (CRL)** in the first trimester, and **biparietal diameter (BPD)**, **head circumference (HC)**, **abdominal circumference (AC)**, and **femur length (FL)** in later pregnancy. - These are growth parameters, distinct from soft markers for chromosomal risk. *Fetal age* - **Fetal age** (gestational age) is primarily determined by **crown-rump length (CRL)** in the first trimester, which is the most accurate method. - Later, BPD, HC, AC, and FL are used for dating, but soft markers do not determine fetal age.

Question 1089: A lady with 10-12 wks pregnancy develops acute retention of urine. The likely cause is-

A. Prolapse uterus
B. Fibroid
C. Retroverted uterus (Correct Answer)
D. Urinary tract infection

Explanation: ***Retroverted uterus*** - A **retroverted uterus** can become impacted in the **pelvic cavity** as it grows during pregnancy, causing compression of the urethra. - This impaction typically occurs between **10-14 weeks of gestation**, leading to acute urinary retention. *Prolapse uterus* - Uterine prolapse is less likely to cause acute urinary retention in early pregnancy, as the pregnant uterus tends to **ascend out of the pelvis** at this stage. - While prolapse can be associated with urinary symptoms, acute retention due to prolapse is more common in **non-pregnant** or **postpartum** states. *Fibroid* - A **fibroid**, especially a large one or one located in the lower uterine segment, can obstruct the bladder outlet. - However, the most classic cause of acute urinary retention in early pregnancy is a **retroverted uterus**, which is more commonly implicated than fibroids in this specific scenario. *Urinary tract infection* - A **urinary tract infection (UTI)** can cause dysuria, frequency, and urgency, and in severe cases, might lead to urinary retention due to urethral inflammation or bladder dysfunction. - While a UTI is possible, in the context of early pregnancy and acute retention, a **mechanical obstruction** from uterine displacement is a more specific and common cause.

Question 1090: Umbilical artery Doppler is done to assess

A. Fetal weight
B. Fetal oxygenation
C. Fetal maturity
D. Placental function (Correct Answer)

Explanation: ***Placental function*** - Umbilical artery Doppler assesses **blood flow resistance** within the placenta, which is a direct indicator of its functional capacity. - Increased resistance, indicated by a high **systolic/diastolic (S/D) ratio** or absent/reversed end-diastolic flow, suggests inadequate placental perfusion and function. *Fetal weight* - Fetal weight is primarily assessed through **ultrasound biometry**, measuring parameters like head circumference, abdominal circumference, and femur length. - While compromised placental function can affect fetal growth, Doppler itself does not directly measure fetal weight. *Fetal oxygenation* - Fetal oxygenation is more directly assessed through **non-stress tests (NST)**, **biophysical profiles (BPP)**, and fetal scalp blood sampling for pH. - Abnormal umbilical artery Doppler findings can *indirectly* suggest potential for reduced oxygenation due to placental insufficiency, but it's not a direct measure. *Fetal maturity* - Fetal maturity, particularly lung maturity, is assessed by analyzing **amniotic fluid** for ratios like **lecithin/sphingomyelin** or presence of **phosphatidylglycerol**. - Umbilical artery Doppler provides no information about fetal organ development or gestational age-related maturity.

Practice by Chapter

Fetal Assessment Techniques

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Hypertensive Disorders in Pregnancy

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Intrauterine Growth Restriction

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Multiple Gestation

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Rh Isoimmunization and Other Blood Group Incompatibilities

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Intrauterine Fetal Therapy

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Prenatal Diagnosis and Genetic Counseling

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Placental Abnormalities

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Preterm Labor and Delivery

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Management of Medical Disorders in Pregnancy

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