Vasa Previa Diagnosis and Treatment to Prevent Stillbirth

This condition may develop along with placenta previa

Pregnant woman having ultrasound scan
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Vasa previa is a serious pregnancy complication that occurs in an estimated 1 in 2,500 pregnancies. Get the facts on this medical condition and whether you're at risk.

In vasa previa, blood vessels involved in the baby's circulation grow along the membranes in the lower part of the uterus at the cervical opening. When the condition is not detected in advance, the blood vessels can rupture during labor.

Vasa previa may involve velamentous insertion of the umbilical cord and can develop in association with placenta previa. Undetected vasa previa can lead to stillbirth or infant loss.

Causes of Vasa Previa

In a normal pregnancy, the blood vessels of the umbilical cord and the placenta are insulated inside the amniotic sac. In vasa previa, blood vessels are present at the membranes without this protection due to either velamentous insertion of the umbilical cord or an abnormally formed multi-lobed placenta.

Vasa previa of either type can develop as a complication of placenta previa, or a low-lying placenta, being present or having been present at some point during the pregnancy. A velamentous umbilical cord or multi-lobed placenta that exists higher in the uterus would not necessarily mean vasa previa.

Why Vasa Previa Is Dangerous

When a woman with vasa previa goes into labor and the cervix begins to dilate, the blood vessels present at the cervix can rupture. If this occurs, the baby will experience rapid blood loss and may die before doctors are able to do anything about the situation. When vasa previa is not diagnosed before the onset of labor, the chance of stillbirth may be as high as 95 percent.

Besides outright rupture, the blood vessels crossing the cervix can easily become compressed when the baby drops further down in the pelvis, decreasing the baby's blood supply and causing drops in the heart rate.

Diagnosis of Vasa Previa

Vasa previa usually causes no outward symptoms during the pregnancy, but doctors can pick up markers for the condition as early as the second trimester via ultrasound. Following up a standard ultrasound with a color Doppler ultrasound can give doctors a good idea whether vasa previa is present.

Risk Factors

Pregnancies involving known placenta previa, velamentous cord insertion, or multi-lobed placenta may be at risk for vasa previa. In addition, multiple pregnancies or pregnancies conceived via IVF are at increased risk. Vasa previa in a previous pregnancy does not appear to be a risk factor.

Treating Vasa Previa

When doctors are able to diagnose vasa previa early in the pregnancy before the onset of labor, mothers may be hospitalized in the third trimester to ensure rapid access to medical care should blood vessels rupture. The doctor will most likely perform a C-section around 35 weeks of pregnancy.​

This strategy drastically improves the odds that the baby will survive. Early delivery carries some risk to the baby because of normal consequences of prematurity, but the risks are much lower than if the vasa previa is not detected and labor progresses normally.

View Article Sources
  • International Vasa Previa Foundation, "FAQ." 
  • Lee, Wesley, Virginia L. Lee, Janet S. Kirk, Christopher T. Sloan, Ramada S. Smith, and Christine H. Comstock, "Vasa Previa: Prenatal Diagnosis, Natural Evolution, and Clinical Outcome." Obstetrics & Gynecology 2000. 
  • Oyelese, Yinka, and John C. Smulian, "Placenta Previa, Placenta Accreta, and Vasa Previa." Obstetrics & Gynecology 2006.