Placental abruption and subchorionic hemorrhage in the first half of pregnancy: US appearance and clinical outcome.

In 30 pregnant patients who experienced vaginal bleeding between 10 and 20 weeks gestation, subchorionic hematomas were demonstrated on ultrasound examination. In 18 patients (60%), the margin of the placenta was separated from the uterine wall. In 15 patients the outcome was favorable (full-term delivery of normal infant) and in 15 patients the outcome was unfavorable (seven preterm births, four stillbirths, three spontaneous abortions, one therapeutic abortion). The major prognostic factor related to pregnancy outcome was the volume of the hematoma and, to a lesser extent, the relative volume of the hematoma (volume of hematoma divided by volume of gestational sac). For a volume less than 60 ml, the outcome tended to be favorable, and for a relative volume less than 0.4, the outcome tended to be favorable.