How is antenatally diagnosed vasa previa managed?

Vasa previa occurs when unprotected fetal vessels traverse the membranes in close proximity to the internal cervical os, placing the fetus at risk of rapid exsanguination if the membranes rupture or during labor.

The 2024 International Expert Consensus (Oyelese et al.) emphasizes that:

• There is no consensus on an exact distance cut-off to define vasa previa.
• The diagnosis should not be limited to vessels within 2 cm of the internal os.
• Any unprotected fetal vessel that could be compressed or ruptured with labor, cervical dilation, or ROM should be managed as vasa previa.

Risk factors include IVF, bilobed/succenturiate-lobed placentas (type 2), velamentous cord insertion (type 1), and second-trimester placenta previa or low-lying placenta (type 3).

This page integrates: International Consensus 2024, SMFM 2015,  and Vintzileos 2015

Diagnosis and confirmation

• Diagnosis is made by transvaginal ultrasound with color Doppler.
• Assess:
  • Unprotected vessels approaching or crossing the os
  • Placental morphology and accessory lobes
  • Cord insertion (including velamentous insertion)
• Reassess at 28–32 weeks to confirm persistence.

Surveillance

• Vintzileos AM , et.al. recommend measuring the cervical length every 1-2 weeks in asymptomatic patients from 28 weeks of gestation until delivery. If cervical length is less than 25 mm then hospitalization should be considered.
• Oyelese Y, et. al., recommend " ultrasound examinations to evaluate fetal growth every 4 weeks starting at 24 weeks of gestation... because any type of velamentous cord insertion is associated with an increased risk of fetal growth restriction."

Outpatient vs. inpatient management

The International Consensus supports a personalized approach:

Outpatient management (strict selection)

• Asymptomatic, without symptoms such as
  • Bleeding
  • Regular painful uterine contractions
  • Loss of fluid
• Without risk factors for spontaneous preterm delivery such as
  • Short cervix
  • History of spontaneous preterm delivery
  • Positive fetal fibronectin
• Reliable rapid access to hospital
• Ability to return immediately for symptoms
• Shared decision-making

Inpatient management (typically starting at 30 weeks)

• Short cervix or progressive cervical change
• Vaginal bleeding or contractions
• Loss of fluid
• History of spontaneous preterm delivery
• Positive fetal fibronectin
• Limited access to care
• Other maternal or obstetric complications

The Society for Maternal-Fetal Medicine recommends the decision for prophylactic hospitalization may be individualized.

Antenatal corticosteroids (2024 Consensus)

2024 International Expert Consensus Statement:

Situations where delivery within 7 days may be anticipated:

• New or recurrent vaginal bleeding
• Preterm contractions or preterm labor
• Rapid cervical change or cervical shortening
• Prelabor rupture of membranes
• Worsening maternal or fetal status

Timing and mode of delivery (2024 Consensus)

Earlier guidelines recommended 34–35 weeks based on older modeling. However, the 2024 International Expert Consensus now recommends:

Deliver earlier (<35 weeks) for:

• Bleeding
• Contractions / evolving preterm labor
• Short cervix
• Prelabor rupture of membranes
• Other obstetric indications

Mode of delivery: Cesarean delivery is recommended; avoid induction and AROM in the presence of exposed fetal vessels.

References