Clinical significance of subchorionic and retroplacental hematomas detected in the first trimester of pregnancy

OBJECTIVE: To evaluate the long-term clinical significance of intrauterine hematomas detected in the first trimester of pregnancy in a general obstetric population. METHODS: A prospective study was designed to compare perinatal outcomes in 187 pregnant women with intrauterine hematomas and 6488 controls in whom hematomas were not detected at first-trimester ultrasonographic examination. RESULTS: The incidence of intrauterine hematoma in the first trimester in a general obstetric population was 3.1%. A retroplacental position of the hematoma was significantly correlated with an increased risk for adverse maternal and neonatal complications. The presence or absence of symptoms of threatened abortion did not affect these outcomes. The rates of operative vaginal delivery (relative risk [RR] 1.9; confidence interval [CI] 1.1, 3.2) and cesarean delivery (RR 1.4; CI 1.1, 1.8), as well as the rates of pregnancy-induced hypertension (RR 2.1; Cl 1.5, 2.9) and preedampsia (RR 4.0; CI 2.4, 6.7), were significantly greater in the hematoma group. Placental abruption (RR 5.6; CI 2.8, 11.1) and placental separation abnormalities (RR 3.2; Cl 2.2, 4.7) were also significantly more frequent in the hematoma group. Perinatal complications, including the rate of preterm delivery (RR 2.3; CI 1.6, 3.2), fetal growth restriction (RR 2.4; CI 1.4, 4.1), fetal distress (RR 2.6; CI 1.9, 3.5), meconium-stained amniotic fluid (RR 2.2; CI 1.7,2.9), and neonatal intensive care unit admission (RR 5.6; CI 4.1, 7.6), were also significantly increased in this group. Furthermore, the frequency of intrauterine demise and perinatal. mortality was increased in the hematoma group, but this difference did not reach statistical significance (Ps = .6 and .2). CONCLUSION: Our study suggests that the presence of an intrauterine hematoma during the first trimester may identify a population of patients at increased risk for adverse pregnancy outcome.