What is Vasa Previa and can it Harm a Baby?

Complications during the pregnancy and delivery process can lead to poor outcomes for mother or baby. An extremely rare complication of pregnancy, vasa previa presents a severe threat to a developing baby. It occurs when the blood vessels of the umbilical cord run very close to the opening of the cervix. Because the cushioning of the umbilical cord itself does not protect these blood vessels, they’re at high risk of rupturing when the membranes, or water, break prior to delivery.

Vasa previa can be very dangerous to a baby. In fact, around half of all undiagnosed cases lead to stillbirth. On the other hand, when a provider correctly diagnoses the condition during pregnancy, survival rates increase to around 97%.

Symptoms of Vasa Previa

Unfortunately, the symptoms of vasa previa are often silent until labor. In some cases, a provider does not diagnose it until labor begins when the fetus is already experiencing distress, or a provider may diagnose it following a stillbirth.

All pregnant women should be on the lookout for painless vaginal bleeding. Dark, burgundy-colored bleeding from the vagina could indicate that the blood is coming from the fetus, not the mother. Any vaginal bleeding during pregnancy is worthy of immediate, emergency medical attention.

What Causes Vasa Previa?

Vasa previa is an anatomical abnormality of pregnancy. One cause is velamentous cord insertion, which occurs when the umbilical cord goes into the membranes, or waters, leaving the vessels unprotected. Another possible cause is bilobed placenta, which occurs when the placenta is in two separate pieces. In general, a mother may be at increased risk for developing vasa previa if:

  • The placenta is low-lying (placenta previa)
  • Previous births required a cesarean section
  • A pregnancy occurred via in vitro fertilization
  • A mother had a previous uterine surgery
Diagnosing Vasa Previa

The best method for diagnosing vasa previa is via transvaginal scan. This type of ultrasound scan is internal and may occur during the first trimester as a part of routine prenatal care. Adding colored Doppler allows a provider to see the area more clearly and determine the presence of any potential umbilical cord abnormalities like vasa previa. However, since this condition is so rare, it’s likely that a provider will not screen for it unless a mother has one or more of the risk factors outlined above.

Management of Vasa Previa

If a provider diagnoses vasa previa during the antenatal period, a baby’s chances of survival are excellent. In some cases, the condition resolves spontaneously as pregnancy progresses. Health care providers should monitor anyone who receives a diagnosis of vasa previa very closely throughout pregnancy. A pregnancy will continue for as long as it is safe. As soon as a baby is viable, or the condition poses an imminent threat to the baby’s safety, a provider will deliver the baby via cesarean section. Determining the date of delivery will be a balance between the risks of early delivery and the rupture of the membranes.

In some cases, a provider will recommend complete bed rest in the third trimester, and almost all women diagnosed with vasa previa should be on pelvic rest. In most cases, a doctor will perform a cesarean delivery between 35 and 37 weeks. It would be extremely dangerous for the membranes to rupture spontaneously, as this could lead to oxygen deprivation, fetal distress, and stillbirth.

When a health care provider diagnoses vasa previa during pregnancy, it can lead to excellent outcomes for both mom and baby. However, a failure to diagnose this rare complication of pregnancy could prove catastrophic to the unborn child. It’s essential to intervene and treat this condition as soon as possible.