Introduction: Vasa previa is an uncommon obstetrical complication that poses a high risk of fetal demise if not recognized before rupture of membranes. It is vital that providers recognize risk factors for vasa previa and diagnose this condition before the onset of labor so that fetal shock or demise is prevented.
Methods: We report a patient with a bilobed placenta and perinatal hemorrhage caused by vasa previa that was not detected with antepartum ultrasound. A review of the literature published between January 1965 and August 2002 was conducted using a MEDLINE-assisted search using the key words "vasa previa," "bilobed placenta," and "succenturiate."
Results: Risk factors for vasa previa have been identified. Advances in ultrasound have led to improved ability to diagnose this condition. Evaluation of patients in high-risk groups with transvaginal color flow Doppler ultrasound should be considered. The accuracy of this technique for diagnosing vasa previa is not known, nor is the true incidence of this condition. Antepartum diagnosis is associated with improved outcomes but does not eliminate morbidity and mortality.
Conclusions: A high index of suspicion for vasa previa at the time of amniotomy is required, because all cases cannot be diagnosed before the onset of labor.