Prenatal ultrasound diagnosis of massive subchorionic thrombohematoma.

Massive subchorionic thrombohematoma is a rare condition in which a large maternal blood clot separates the chorionic plate from the villous chorion. This condition is usually complicated by intrauterine growth restriction, and is often associated with fetal distress and perinatal death. We present a case in which the diagnosis of massive subchorionic thrombohematoma was made at 24 weeks' gestation. Doppler ultrasound helped to confirm the diagnosis and demonstrated severely abnormal umbilical blood flow. Two days after the diagnosis, fetal distress prompted emergency Cesarean delivery of a growth-restricted infant.