Transvaginal ultrasonography was used to evaluate antepartum bleeding in a group of 76 patients at varying gestational ages with suspected placenta previa. The clinical outcome of 16 patients with persistent placenta previa was documented. Nine of the 16 patients had placental lacunar blood flow. Two of the nine patients were lost to follow-up. At cesarean section the seven patients with lacunar flow had a higher incidence of blood loss, transfusion requirements, abnormally implanted placenta, and cesarean hysterectomy than the six patients in whom no lacunar flow patterns were seen (p = 0.002). The finding of these flow patterns with abnormally located placentas suggests the anticipation of significant blood loss and probable extension of operative procedures to stop the blood loss.