Clinical Significance of Subchorionic and Retroplacental Hematomas Detected in the First Trimester of Pregnancy

AIMS: 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 the perinatal outcome in 187 pregnant women with intrauterine hematomas to 6488 controls in which hematomas were not detected at first trimester by ultrasound 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 (RR: 1.9; CI: 1.1-3.2) and cesarean section (RR: 1.4; CI: 1.1-1.8) were significantly greater in the hematoma group as compared to the control group, as well as the rates of pregnancy induced hypertension (RR: 2.1; CI: 1.5-2.9) and preeclampsia (RR: 4.0; CI: 2.4-6.7). Placental abruption (RR: 5.6; CI: 2.8-11.1), and the incidence of placental separation abnormalities was also significantly more frequent in the hematoma group (RR: 3.2; CI: 2.2-4.7). Perinatal complications, including the rate of preterm delivery (RR: 2.3; CI: 1.6-3.2), intrauterine 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 NICU 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 (p = 0.6 and p = 0.2). CONCLUSION: The authors' 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.