Serial Ultrasound and Monitoring for Velamentous Cord Insertion
Yes, serial ultrasound surveillance is recommended for pregnancies with velamentous cord insertion (VCI) due to the significantly increased risk of adverse perinatal outcomes including intrauterine fetal demise, fetal growth restriction, and preterm delivery.
Initial Detection and Assessment
VCI should be systematically evaluated at the routine second-trimester anatomy scan (18-22 weeks) using transabdominal ultrasound with color Doppler. 1 The ACR guidelines emphasize that both VCI and vasa previa are more commonly present in multiple gestations and deserve dedicated evaluation at this point in pregnancy, as both conditions are associated with adverse pregnancy outcomes. 1
- Color Doppler ultrasound has 67% sensitivity and 100% specificity for detecting VCI in the second trimester 2
- When VCI is identified, transvaginal ultrasound with color Doppler is superior for detecting concurrent vasa previa 2
- Direct visualization of abnormal cord insertion on routine ultrasound without color Doppler is successful in only approximately 1% of cases 3
Surveillance Protocol
Once VCI is diagnosed, serial surveillance should be performed for the remainder of pregnancy, focusing on fetal growth, amniotic fluid assessment, and umbilical artery Doppler velocimetry. 1
Specific Monitoring Parameters:
- Fetal biometry every 3-4 weeks to assess for growth restriction, as VCI increases the risk of small for gestational age (SGA) by 1.5-4.3 fold 3, 4, 5
- Umbilical artery Doppler assessment when growth restriction is suspected or documented 1
- Amniotic fluid volume assessment at each surveillance visit, as polyhydramnios is associated with VCI 4
Rationale for Serial Monitoring
The evidence strongly supports intensive surveillance based on documented adverse outcomes:
- Intrauterine fetal demise risk is increased 9-fold (adjusted OR 9.56) in pregnancies with VCI 5
- Fetal growth restriction occurs 2.3-4.3 times more frequently 3, 4
- Preterm delivery risk is doubled (OR 2.12-4.6) 3, 4
- Low Apgar scores are 1.8-2.5 times more common 3
- Placental abruption risk is increased 8-fold 4
Critical Pitfall to Avoid
Standard nonstress testing (NST) is NOT effective for detecting uteroplacental problems associated with VCI. Only 5% of patients with VCI showed pathologic NST results at prenatal visits, and abnormal umbilical artery Doppler velocimetry was found in none of the examined cases (excluding those with preeclampsia). 3 This means that relying on NST alone will miss the majority of at-risk pregnancies with VCI.
Special Considerations for Multiple Gestations
VCI occurs in up to 22% of monochorionic twins and requires even more intensive surveillance. 1, 2
- Monochorionic twins with VCI should begin surveillance at 16 weeks with fetal biometry every 2-3 weeks 1
- VCI in one or both twins increases the risk of twin-twin transfusion syndrome from 7% to 27% 1
- The presence of VCI with discordant cord insertion sites further increases the risk of growth discordance 1
Delivery Planning
While serial monitoring is essential, the mode of delivery depends on additional risk factors rather than VCI alone. 2 Vaginal delivery is generally preferred for singleton pregnancies with isolated VCI without vasa previa, but cesarean delivery should be strongly considered when VCI is combined with fetal growth restriction and abnormal Doppler findings. 2 For monochorionic twins with VCI and additional complications, elective cesarean delivery should be considered. 2