462: Subchorionic hematomas and adverse pregnancy outcomes among twin pregnancies

Abstract

Subchorionic hematoma (SCH) is associated with fetal loss, placental abruption and preterm birth among singleton pregnancies. Studies examining this relationship in twins are limited and have conflicting results. We sought to understand the association between SCH, first trimester bleeding and adverse pregnancy outcomes in women with twin pregnancies. Retrospective cohort study of all twin pregnancies ≥ 12 weeks over a 12-year period at a single institution, all of whom had a first trimester ultrasound. We excluded women with monoamniotic twins, fetal anomalies, history of fetal reduction or spontaneous reduction, and/or TTTS. We compared pregnancy outcomes in women with and without a SCH <14 weeks. Among women with a SCH, we further compared outcomes between women with and without vaginal bleeding, and by the size of the hematoma. Our primary outcome was delivery < 34 weeks. Secondary outcomes included delivery at earlier gestational ages, IUFD, pre-eclampsia, abruption, blood transfusion at delivery and IUGR. Chi square, Fisher’s exact, student’s t-test, Pearson correlation, and logistic regression were used, as appropriate. A total of 834 women with twin pregnancies met inclusion criteria for the study, 81 (9.7%) of whom had a SCH prior to 14 weeks. There were no differences in baseline characteristics or pregnancy outcomes between women with and without a SCH; however, SCH was independently associated with blood transfusion at delivery (aOR 2.84, 95% CI 1.29, 6.22). Among women with a SCH, 41/81 (50.6%) also had vaginal bleeding, and these women had a significantly higher rate of preterm birth (Table 1). In women with a SCH, the SCH volume did not correlate with gestational age at delivery (p=0.770), nor did the largest diameter of the SCH (p=0.374). SCH size also did not correlate with the risk of transfusion, but we were underpowered for this analysis. In women with twin pregnancies, SCH is not associated with adverse outcomes, regardless of the size of the SCH, aside from the risk of transfusion at delivery. However, if the SCH is associated with vaginal bleeding, there is an increased risk of preterm birth.