What is the preferred mode of delivery for a velamentous (velamentous) umbilical cord insertion?

Preferred Mode of Delivery for Velamentous Umbilical Cord Insertion

Vaginal delivery remains the preferred mode for velamentous umbilical cord insertion in singleton pregnancies without vasa previa, but cesarean delivery should be strongly considered when vasa previa is present or when the diagnosis is made prenatally with concerning features. 1

Primary Delivery Approach

The mode of delivery for velamentous cord insertion depends critically on whether vasa previa is present:

• Without vasa previa: Vaginal delivery is generally preferred, as cesarean delivery is reserved for obstetric indications rather than velamentous insertion alone 1
• With vasa previa: Planned cesarean delivery at 38 weeks gestation is strongly recommended to prevent catastrophic fetal hemorrhage from vessel rupture during membrane rupture or labor 2, 3

Key Clinical Decision Points

When to Plan Cesarean Delivery

Absolute indications for cesarean delivery:

• Confirmed vasa previa on prenatal ultrasound, particularly when vessels cross the internal cervical os 3
• Velamentous insertion with vessels located in membranes overlying the cervix 3
• Antepartum or intrapartum vaginal bleeding with fetal distress in the setting of known velamentous insertion 4

Relative indications for cesarean delivery:

• Velamentous insertion diagnosed prenatally in twin gestations (present in up to 22% of monochorionic twins) with additional risk factors 1
• Velamentous insertion with concurrent fetal growth restriction and abnormal Doppler findings 5
• Preterm labor in the setting of velamentous insertion, where rapid delivery may be needed 4

When Vaginal Delivery is Appropriate

Vaginal delivery can proceed when:

• Velamentous insertion is isolated without vasa previa 1
• The cord insertion site is distant from the cervical os 2
• No antepartum bleeding or fetal distress is present 4
• Continuous fetal monitoring is available throughout labor 4

Critical Management Considerations

Prenatal Diagnosis is Essential

• Velamentous cord insertion should be systematically assessed at the routine second-trimester anatomy scan (18-22 weeks) using transabdominal ultrasound 1
• Color Doppler ultrasound has 67% sensitivity and 100% specificity for detecting velamentous insertion in the second trimester 6, 7
• Transvaginal ultrasound with color Doppler is superior for detecting vasa previa when velamentous insertion is identified 3, 7

Intrapartum Monitoring Requirements

For planned vaginal delivery with velamentous insertion:

• Continuous electronic fetal monitoring is mandatory throughout labor 4
• Maintain high suspicion for fetal distress, particularly with membrane rupture 4
• Have immediate cesarean delivery capability available, as 15 of 31 cases (48%) in one series required cesarean section 4
• Consider artificial rupture of membranes only under controlled circumstances with immediate access to operative delivery 4

Common Pitfalls and How to Avoid Them

Failure to diagnose prenatally: The most dangerous pitfall is missing the diagnosis entirely. Systematic evaluation of placental cord insertion should be routine at every anatomy scan 6. When velamentous insertion is found, specifically evaluate for vasa previa with transvaginal color Doppler 3, 7.

Underestimating risk in twin pregnancies: Velamentous insertion occurs in 22% of monochorionic twins and significantly increases adverse outcomes including fetal growth restriction, preterm delivery, and intrauterine fetal demise 1. These pregnancies warrant closer surveillance and lower threshold for cesarean delivery.

Misinterpreting intrapartum bleeding: Vaginal bleeding with fetal distress in the setting of velamentous insertion should be assumed to be fetal hemorrhage from ruptured vessels until proven otherwise 4. This requires immediate cesarean delivery rather than expectant management.

Delaying delivery when vasa previa is present: Once vasa previa is diagnosed with velamentous insertion, planned cesarean delivery at 38 weeks prevents the catastrophic outcomes associated with spontaneous labor and membrane rupture 2, 3.

Special Populations

Multiple Gestations

• Velamentous insertion is 15-22 times more common in twin pregnancies, particularly monochorionic twins 1, 3
• The presence of velamentous insertion in one or both twins increases risk of twin-twin transfusion syndrome from 7% to 27% 1
• Consider elective cesarean delivery for monochorionic twins with velamentous insertion and additional complications 1

Growth-Restricted Fetuses

• Velamentous insertion increases risk of fetal growth restriction, small for gestational age, and lower gestational age at birth 1
• When combined with abnormal Doppler findings (absent or reversed end-diastolic velocity), cesarean delivery should be strongly considered based on the clinical scenario 5