Vasa previa is the presence of unprotected fetal blood vessels, arterial andor venous, coursing within the fetal membranes over or in close proximity to the internal cervical os. These vessels are not supported by placental tissue or the umbilical cord. Their exposed location places them at high risk of rupture or compression during labor or membrane rupture, which can result in acute fetal hemorrhage, stillbirth, or neonatal death if not diagnosed antenatally.
