gynecology and obstetrics
Vasa Previa
Key Points
In vasa previa, membranes that contain fetal blood vessels connecting the umbilical cord and placenta overlie or are within 2 cm of the internal cervical os. Vasa previa may be accompanied by other placental abnormalities, such as velamentous insertion, which increases the risk of fetal hemorrhage when the fetal membranes rupture. Suspect vasa previa based on symptoms and (painless vaginal bleeding, rupture of membranes, fetal bradycardia) and/or findings during routine prenatal ultrasonography. Use transvaginal ultrasonography to confirm vasa previa and to distinguish it (fixed umbilical cord) from funic presentation (movable cord). Check for compression of the cord using nonstress testing, possibly twice a week beginning at 28 to 30 weeks. Schedule cesarean delivery, or if premature rupture of the membranes occurs, vaginal bleeding continues, or fetal status is nonreassuring, do emergency cesarean delivery. 