Maternal-Fetal Medicine Practice Questions

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

Isthmus. ***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.

Q: Singer's alkali denaturation test is used to differentiate

Fetal blood from maternal blood. ***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.

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

Retroverted uterus. ***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.

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

> 15mm. ***> 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.

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

Anti-Ro antibody. ***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.

Q: Soft markers on ultrasonography are helpful in diagnosing?

Chromosomal anomalies. ***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.

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

Retroverted uterus. ***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.

Q: Umbilical artery Doppler is done to assess

Placental function. ***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.

Question 1

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

Accepted Answer

Isthmus

Answer

Infundibulum

Answer

Ampulla

Answer

Interstitial

Question 2

Singer's alkali denaturation test is used to differentiate

Accepted Answer

Fetal blood from maternal blood

Answer

Arterial blood from venous blood

Answer

Oxygenated blood from deoxygenated blood

Answer

Adult hemoglobin from sickle cell hemoglobin

Question 3

Which of the following statements is true regarding cerclage?

Accepted Answer

Prolapsing membranes can be reduced with Trendelenburg positioning and bladder filling prior to cerclage placement.

Answer

Timing of surgery is between 12 → 14 weeks gestation.

Answer

No need of antibiotic prophylaxis as membranes not ruptured.

Answer

Shirodkar procedure is most often selected.

Question 4

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

Accepted Answer

Retroverted uterus

Answer

Bladder neck obstruction due to ovarian cyst

Answer

Fibroid uterus

Answer

Neurogenic bladder

Question 5

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

Accepted Answer

Transvaginal ultrasound

Answer

Serum beta-hCG levels

Answer

FAST (Focused Assessment with Sonography in Trauma)

Answer

Diagnostic laparoscopy

Question 6

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

Accepted Answer

> 15mm

Answer

7 to < 9mm

Answer

9 to <= 15mm

Answer

4 to < 7mm

Question 7

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

Accepted Answer

Anti-Ro antibody

Answer

Anti-Sm antibody

Answer

Anti-RNP antibody

Answer

Anti-dsDNA antibody

Question 8

Soft markers on ultrasonography are helpful in diagnosing?

Accepted Answer

Chromosomal anomalies

Answer

Site of pregnancy

Answer

Fetal size

Answer

Fetal age

Question 9

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

Accepted Answer

Retroverted uterus

Answer

Prolapse uterus

Answer

Fibroid

Answer

Urinary tract infection

Question 10

Umbilical artery Doppler is done to assess

Accepted Answer

Placental function

Answer

Fetal weight

Answer

Fetal oxygenation

Answer

Fetal maturity

Maternal-Fetal Medicine — MCQs

Maternal-Fetal Medicine — MCQs

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