Ultrasound-Detected Subchorionic Hemorrhage and the Obstetric Implications

OBJECTIVE: To estimate the association between the ultrasonographic diagnosis of subchorionic hemorrhage and adverse pregnancy outcomes. METHODS: This was a retrospective cohort study of all consecutive women undergoing routine ultrasonography before 22 weeks with a singleton gestation at one institution from 1994 to 2008. Presence or absence of subchorionic hemorrhage defined the two study groups. The primary outcomes were abruption, intrauterine growth restriction defined as birth weight less than the 10th percentile, and nonanomalous intrauterine fetal demise after 20 weeks. Secondary outcomes included pre-eclampsia, preterm premature rupture of membranes, and preterm delivery before 37 weeks and before 34 weeks of gestation. Univariable, bivariate, and multiple logistic regression analyses were performed. RESULTS: Of the 63,966 women in the patient population, 1,081 had subchorionic hemorrhage (1.7%). Women with a subchorionic hemorrhage were at increased risk of abruption (n = 432, 3.6% compared with 0.6%, adjusted odds ratio 2.6, 95% confidence interval 1.8-3.7) and of preterm delivery (n = 6,601, 15.5% compared with 10.5%, adjusted odds ratio 1.3, 95% confidence interval 1.1-1.5), even after adjusting for bleeding during pregnancy, chronic hypertension, body mass index, race, diabetes mellitus, tobacco use, and previous preterm delivery. CONCLUSION: Women with ultrasound-detected subchorionic hemorrhage before 22 weeks of gestation are at increased risk of placental abruption and preterm delivery but are not at increased risk of other adverse pregnancy outcomes.