vasa previa

vasa previa A condition in which blood vessels within the placenta or the umbilical cord are trapped between the fetus and the opening to the birth canal. Vasa previa carries a high risk that the fetus will die from blood loss due to a vessel tearing at the time the fetal membranes rupture or during labor and delivery. Another danger is lack of oxygen to the fetus. Vasa previa tends to occur with a lowlying or unusually formed placenta and multiple gestation. Vasa previa may not be suspected until the fetal vessel ruptures. Vasa previa can be documented via transvaginal ultrasound in combination with color Doppler imaging. When vasa previa is diagnosed, a C-section delivery is done to avoid an emergency.