Abnormal Placental Structure and Vasa Previa Confirmation of the Relationship

Vasa previa is a result of a velamentous cord insertion where the umbilical vessels lie over the internal cervical os. This condition is relatively rare, with an incidence of approximately 1 per 2000 to 5000 deliveries. If undiscovered, fetal mortality can be as high as 58% to 73%. 1 Patients with vasa previa may have second- or third-trimester bleeding or may be asymptomatic. Advances in ultrasonography and color Doppler imaging have greatly improved prenatal detection of vasa previa. 2 Risk factors include in vitro fertilization, 3 placenta previa, multiple gestation, abnormal placental structure, and velamentous cord insertion. Because of the considerable risk it poses to the fetus, vasa previa should be ruled out in any patient who had second- or third-trimester bleeding or the presence of such risk factors.