A 38-year-old woman, gravida 3, para 2, at 32 weeks' gestation comes to the physician because of bleeding from the vagina. She states that this morning she passed 2 quaer-sized clots of blood from her vagina. Otherwise, she states that she is feeling well. The baby has been moving normally and she has had no contractions or gush of fluid from the vagina. Her obstetrical history is significant for 2 low-transverse cesarean deliveries for non-reassuring fetal hea rate tracings. An ultrasound is performed that demonstrates a complete placenta pre. For which of the following conditions is this patient at highest risk?