What are the management and complications of a pregnancy with velamentous cord insertion?

Management and Complications of Velamentous Cord Insertion

Initial Detection and Diagnosis

Velamentous cord insertion (VCI) should be systematically evaluated at the routine second-trimester anatomy scan (18-22 weeks) using transabdominal ultrasound with color Doppler, as this abnormality significantly increases risks of stillbirth, growth restriction, and multiple adverse perinatal outcomes. 1, 2

Diagnostic Approach

• Color Doppler ultrasound achieves 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, which occurs with higher frequency when VCI is present 1, 2, 3
• VCI occurs in approximately 1.4% of singleton pregnancies but increases to 22% in monochorionic twin gestations 1, 4

Surveillance Protocol

Once VCI is diagnosed, serial ultrasound surveillance every 3-4 weeks for singletons (or every 2-3 weeks starting at 16 weeks for monochorionic twins) focusing on fetal growth, amniotic fluid volume, and umbilical artery Doppler velocimetry is required for the remainder of pregnancy. 1, 2

Monitoring Components

• Fetal biometry at each visit to assess for growth restriction 2
• Amniotic fluid assessment (VCI increases risk of polyhydramnios) 5
• Umbilical artery Doppler velocimetry when growth restriction is suspected or documented 2
• Cervical length assessment via transvaginal ultrasound to stratify preterm delivery risk 1

Special Considerations for Multiple Gestations

• VCI in monochorionic twins requires intensified surveillance every 2-3 weeks beginning at 16 weeks 1, 2
• The presence of VCI in one or both twins increases twin-twin transfusion syndrome risk from 7% to 27% 1, 2, 3
• Fetal echocardiography should be considered in monochorionic gestations, as cardiac anomaly risk is 8-fold higher in monochorionic-monoamniotic twins 1

Complications and Adverse Outcomes

VCI is independently associated with a 4-fold increased risk of perinatal mortality and multiple serious complications that persist even when vasa previa cases are excluded. 6, 4

Major Complications

• Stillbirth: 4.12-fold increased risk overall; 9.42-fold when vasa previa excluded 4
• Small-for-gestational-age/growth restriction: 1.93-fold increased risk (4.3-fold in some cohorts) 1, 6, 4
• Preterm delivery: 2.14-fold increased risk overall; 2.69-fold for prenatally diagnosed cases 6, 4
• Placental abruption: 2.94-fold increased risk (8.2-fold in some cohorts) 6, 4
• Preeclampsia/pregnancy-induced hypertension: 1.85-fold and 1.58-fold increased risk respectively 4

Neonatal Complications

• Emergency cesarean delivery: 2.03-fold increased risk 4
• 5-minute Apgar score <7: 1.97-fold increased risk 4
• NICU admission: 1.63-fold increased risk 4
• Lower gestational age at birth in monochorionic twins 1

Mechanism of Injury

• Umbilical blood vessels branch before reaching the placenta and traverse unprotected through fetal membranes 5, 7
• Vessels lack Wharton's jelly protection, making them prone to compression, rupture during membrane rupture, and spontaneous internal ruptures 5, 7

Delivery Planning

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, 3

Delivery Decision Algorithm

• Isolated VCI in singleton without vasa previa: Vaginal delivery is appropriate; cesarean delivery reserved for standard obstetric indications 3
• VCI with concurrent growth restriction and abnormal Doppler: Cesarean delivery should be strongly considered 2, 3
• Monochorionic twins with VCI and additional complications: Elective cesarean delivery recommended 3
• VCI with confirmed vasa previa: Planned cesarean delivery before labor onset (typically 34-37 weeks) 7

Critical Delivery Considerations

• Avoid artificial rupture of membranes when possible due to risk of vessel rupture 7
• Continuous fetal monitoring during labor is essential 7
• Prepare for potential fetal hemorrhage and emergency cesarean delivery 7
• Term delivery by elective cesarean section can avoid severe complications when VCI is diagnosed prenatally 5

Risk Factors Requiring Enhanced Screening

Multifetal gestation (9.2-fold increased risk) and infertility treatments (4.3-fold increased risk) are the strongest independent risk factors for VCI and warrant systematic screening. 6

High-Risk Populations

• Multiple gestations, particularly monochorionic twins 6
• Pregnancies conceived via assisted reproductive technologies 6, 8
• Chronic hypertension (2.2-fold increased risk) 6
• Müllerian anomalies (unicornuate uterus) 8

Common Pitfall

The most critical pitfall is failure to screen for vasa previa when VCI is identified—this oversight can result in catastrophic fetal hemorrhage during labor if vessels rupture with membrane rupture 1, 2, 7. Always perform transvaginal ultrasound with color Doppler to exclude vasa previa when VCI is detected 2, 3.