Vasa Previa
When the baby's blood vessels cross near the opening of the cervix
Vasa previa means some of the baby's blood vessels run through the thin membranes (bag of water) near or over the cervix.
These vessels are not protected by the placenta or by the thick covering of the umbilical cord.
If labor starts or the water breaks, these vessels can tear. The baby can lose blood very quickly.
How is it found?
- ultrasound is used to look for the vessels
- a vaginal ultrasound may give a closer view of the cervix
- color Doppler is an ultrasound setting that shows blood flow
Why is it important?
- these vessels are easy to injure because they are not well protected
- they can tear if labor starts or the water breaks
- the baby can lose blood very quickly
Will I stay in the hospital?
Some patients stay in the hospital before birth. Others can be watched closely at home.
Your doctor will look at bleeding, contractions, your cervix, past early births, and how far you live from the hospital.
When is the baby delivered?
- a cesarean birth (C-section) is planned before labor or before the water breaks
- the SMFM and the ACOG give a general range of about 34 to 37 weeks
- your doctor will choose the safest time for you and your baby
What about steroid shots?
Steroid shots may help the baby's lungs if an early birth is expected.
Your doctor will decide if and when they are needed.
When should I go in right away?
- vaginal bleeding
- your water breaks or may be leaking
- regular contractions or severe pain
- your baby is moving less than usual
What do the medical groups recommend?
- SMFM and ACOG: plan a C-section before labor or the water breaks. Whether you stay in the hospital should be based on your own risks.
- ISUOG: when vasa previa is suspected, vaginal ultrasound with color Doppler can help show whether a baby's blood vessel is near or over the cervix.
Go to Labor and Delivery right away if you have bleeding, leaking fluid, contractions, or less baby movement. If your water breaks after the baby can survive outside the womb, SMFM recommends cesarean delivery.
Medical references used for this handout
- Society for Maternal-Fetal Medicine (SMFM). Consult Series #37: Diagnosis and management of vasa previa. 2015; reaffirmed 2024. SMFM guideline.
- SMFM. Consult Series #44: Management of bleeding in the late preterm period. 2018; reaffirmed 2024. ACOG endorsed. SMFM/ACOG-endorsed guidance.
- American College of Obstetricians and Gynecologists (ACOG). Committee Opinion: Indications for Outpatient Antenatal Fetal Surveillance - section on vasa previa. ACOG guidance.
- International Society of Ultrasound in Obstetrics and Gynecology (ISUOG). Updated Practice Guidelines: routine mid-trimester fetal ultrasound scan - targeted transvaginal color Doppler examination when vasa previa risk factors are present. ISUOG guideline.
- ISUOG Patient Information Series. Vasa Previa. Updated July 2023. ISUOG patient information.