Single Umbilical Artery: Associated Findings
The correct answer is B. Maternal diabetes is associated with single umbilical artery (SUA), though the strongest associations are with major fetal malformations—particularly cardiovascular and renal anomalies—which occur in approximately 40-60% of cases, not 80%. 1, 2
Key Associations with Single Umbilical Artery
Major Fetal Malformations (Addressing Option D)
- Major fetal malformations occur in approximately 40-60% of SUA cases, not 80% as stated in option D 3, 4
- When SUA occurs with other structural abnormalities, the frequency of associated aneuploidy ranges from 4% to 50% 2
- In autopsy studies, 60% of SUA cases had other congenital anomalies 3
- Among live-born infants with SUA, the mean incidence of congenital malformation is 27% 5
Specific Organ System Involvement
- Cardiovascular anomalies show the strongest association, with odds ratios ranging from 5.9 to 20.3 for various cardiac defects 2, 6
- Renal anomalies demonstrate a 3-fold increased risk, with approximately 16% of isolated SUA cases having some form of renal anomaly 2, 5
- Esophageal stenosis or atresia shows the highest odds ratio (OR 25.33) 4
- Musculoskeletal and lung anomalies also show strong associations 3
Perinatal Morbidity and Mortality (Addressing Option C)
- SUA is associated with HIGH fetal mortality, not low as suggested in option C 2, 7
- The risk of stillbirth is nearly 5-fold increased (OR 4.80,95% CI 2.67-8.62) 1, 2
- Intrauterine growth restriction occurs with increased frequency (OR 2.1,95% CI 1.6-2.7) 7, 6
- Perinatal and intrauterine death risk is significantly elevated (OR 5.62,95% CI 4.69-6.73) 7
Maternal Diabetes Association (Option B)
- While the provided guidelines focus primarily on fetal outcomes rather than maternal risk factors, maternal diabetes is a recognized association with SUA in clinical practice 1
- The American College of Obstetricians and Gynecologists recommends comprehensive assessment when SUA is identified, regardless of maternal factors 1, 2
Race Considerations (Addressing Option A)
- The evidence provided does not support race as a significant independent risk factor for SUA 1, 2
- SUA occurs in 0.25% to 1% of singleton pregnancies across populations 1
Clinical Management Implications
Initial Assessment
- A comprehensive assessment of fetal anatomy must be performed when SUA is identified, with particular attention to cardiovascular and renal systems 1, 2
- If cardiac views are adequately visualized and normal on anatomy scan, routine fetal echocardiography is not warranted 1, 8
Surveillance Protocol
- Third-trimester ultrasound examination is recommended to evaluate fetal growth 1, 8
- Weekly antenatal fetal surveillance beginning at 36 weeks of gestation should be considered for fetuses with isolated SUA 1, 2
- Serial growth assessments at 3-4 week intervals provide more reliable measurements 1