Massive subchorionic thrombohematoma: a series of 10 cases.

A retrospective audit identified 10 cases of massive idiopathic subchorionic thrombohematoma. The incidence was 1:3,133. Only six of these pregnancies resulted in a livebirth and only two reached term. In eight cases there were ultrasound abnormalities, including two cases of placentomegaly both of which resulted in a pregnancy loss. There was one placental abruption. Seven of the women were nulliparous. Massive subchorionic thrombohematoma is associated with poor pregnancy outcome. Ultrasound findings of placentomegaly might be a bad prognostic sign.