Subchorionic hemorrhage in first-trimester pregnancies: prediction of pregnancy outcome with sonography

To determine the effects of subchorionic hematoma size, gestational age, and maternal age on pregnancy outcome in patients with vaginal bleeding in the first trimester of pregnancy.

A retrospective review was performed with ultrasound images obtained in 516 patients with vaginal bleeding, a live fetus, and a subchorionic hematoma in the first trimester. Hematoma size was graded according to the percentage of the chorionic sac circumference elevated by the hematoma. Patients were also classified according to gestational age and maternal age. Logistic regression analysis was used to determine the effect of each variable on pregnancy outcome.

The overall spontaneous abortion rate was 9.3% (48 of 516 patients). The rate nearly doubled when the separation was large (18.8%) compared with small and moderate hematomas (7.7% and 9.2%, respectively). A large separation was found to be associated with an almost three-fold increase in risk of spontaneous abortion. The spontaneous abortion rate was approximately twice as high for women aged 35 years or older versus younger women (13.8% and 7.3%, respectively) and for women with bleeding at 8 weeks gestation or less compared with those with bleeding at greater than 8 weeks gestation (13.7% vs 5.9%).

For women with a subchorionic hematoma that is sonographically identified, fetal outcome is dependent on size of the hematoma, maternal age, and gestational age.