Vasa previa is a rarely reported condition in which the fetal blood vessels, unsupported by either the umbilical cord or placental tissue, traverse the fetal membranes of the lower segment of the uterus below the presenting part. The condition has a high fetal mortality due to fetal exsanguination resulting from fetal vessels tearing when the membranes rupture. Despite improvements in medical technology, vasa previa often remains unsuspected until this fatal fetal vessel rupture occurs. Significant reduction in the fetal mortality from this condition depends on a high index of suspicion leading to antenatal diagnosis, and elective delivery by cesarean. We believe transvaginal ultrasound in combination with color Doppler is the most effective tool in the antenatal diagnosis of vasa previa and should be utilized in patients at risk, specifically those with bilobed, succenturiate-lobed, and low-lying placentas, pregnancies resulting from in vitro fertilization, and multiple pregnancy. Where there has been antepartum or intrapartum hemorrhage, especially when associated with fetal heart irregularities, we also recommend a test to exclude fetal blood in the vaginal blood. Similarly, amnioscopy before amniotomy may help to diagnose this condition. Cesarean delivery is the method of delivery of choice, and aggressive resuscitation of the affected neonate may be life saving. With a high index of suspicion, antenatal diagnosis using transvaginal sonography in combination with color Doppler, elective delivery by cesarean, and aggressive resuscitation of the neonate where fetal vessel rupture has occurred, the mortality from this complication may be considerably reduced.
Target audience: Obstetricians & Gynecologists, Family Physicians.
Learning objectives: After completion of this article, the reader will be able to identify the risk factors and associated conditions for vasa previa, to identify the various clinical presentations and management of vasa previa, and to be aware of the diagnostic tools available to make the antepartum diagnosis of vasa previa.