Vasa previa is a rare pregnancy complication involving unprotected fetal blood vessels near or across the cervical opening. These vessels may rupture when labor begins or the membranes break, creating a potentially life-threatening emergency. Prenatal identification and carefully planned delivery can greatly improve outcomes.
What is vasa previa?
During pregnancy, fetal blood vessels normally travel through the protected umbilical cord and placenta.
Vasa previa occurs when some fetal vessels travel through the membranes without adequate protection.
These vessels pass over or near the cervix.
Because they lack the normal cushioning of the umbilical cord, they are vulnerable to injury when the membranes rupture.
A torn fetal vessel can cause rapid blood loss from the baby.
This makes vasa previa different from ordinary umbilical cord compression.
The primary immediate danger is fetal hemorrhage, although oxygen delivery may also be affected.
How vasa previa develops
Vasa previa is associated with certain placental and umbilical cord structures.
One important condition is velamentous cord insertion.
This occurs when the umbilical cord attaches to the membranes rather than directly into the main placental tissue.
Another pattern involves fetal vessels connecting separate placental lobes.
If these vessels cross the cervical opening, they may be damaged during membrane rupture or delivery.
Identifying vasa previa before labor
Prenatal ultrasound is central to identifying vasa previa.
Color Doppler imaging can help doctors visualize fetal vessels and determine their relationship to the cervix.
Patients with certain placental abnormalities may require additional assessment.
The Society for Maternal-Fetal Medicine describes vasa previa as a serious condition that can often be diagnosed before childbirth.
Why early diagnosis matters
An undiagnosed case may become dangerous when the membranes rupture.
Because the bleeding comes from fetal circulation, even a relatively small amount of blood loss can be serious.
When vasa previa is identified during pregnancy, healthcare professionals can plan delivery before labor or membrane rupture.
This reduces the risk of vessel injury.
Treatment and delivery planning
Management depends on gestational age, symptoms, and individual pregnancy circumstances.
A specialist may recommend additional monitoring and a planned cesarean delivery.
The goal is to deliver before labor or membrane rupture while avoiding unnecessary prematurity.
The timing must be individualized.
Some patients may require hospital observation when bleeding, contractions, or other risk factors are present.
What happens if a fetal vessel ruptures?
Vaginal bleeding after membrane rupture may raise concern for vasa previa, especially when accompanied by abnormal fetal heart rate findings.
A suspected vessel rupture requires immediate emergency assessment.
Urgent delivery and neonatal resuscitation may be necessary.
Severe fetal blood loss can require blood transfusion and intensive newborn care.
Common questions around vasa previa
Is vasa previa the same as placenta previa?
No. Placenta previa involves placental tissue covering or approaching the cervix. Vasa previa involves exposed fetal blood vessels near the cervical opening.
Can vasa previa be detected by ultrasound?
Yes. Ultrasound with color Doppler is an important diagnostic method.
Does vasa previa always require cesarean delivery?
Persistent prenatal vasa previa is generally managed through planned cesarean delivery before labor begins.
Can babies survive vasa previa?
Yes. Outcomes are often favorable when the condition is diagnosed before delivery and managed appropriately.
