Characteristics of patients with subchorionic hematomas in the second trimester

The aim of this study was to investigate the etiological characteristics of patients diagnosed with subchorionic hematoma.A case-controlled study was performed to compare characteristics of patients and controls. Via ultrasound examination, 47 pregnant patients were found to have subchorionic hematomas and 1075 had no evidence of subchorionic hematomas (controls). In the second trimester, patients were compared with regard to endocervical Chlamydia trachomatis and other vaginal microorganisms.The overall incidence of subchorionic hematomas in this pregnant population was 4.2%. Maternal clinical characteristics did not differ between cases and controls. Evaluation of the vaginal flora revealed that the positive rates of coagulase-negative staphylococci (cases: 12.8%; controls: 4.1%; P<0.01) and Gardnerella vaginalis (cases: 12.8%; controls: 2.5%; P<0.001) in the cases were significantly higher than those of the controls. The negative rate of Lactobacillus in the cases was significantly higher than that of the controls (cases: 42.6%; controls: 27.6%; P<0.05).Pregnant women with subchorionic hematoma in the first trimester showed changes in vaginal flora in the second trimester, which suggests a possible association with subchorionic hematoma and vaginal flora change.