Subchorionic hematoma volume in the first trimester and risk of spontaneous abortion/Volumen del hematoma sub-coriónico en el primer trimestre y riesgo de aborto espontáneo

to establish an association between subchorionic hematoma volume and risk of spontaneous abortion. patients with viable intrauterine pregnancy between 6 and 13 weeks were included and with diagnosis of subchorionic hematoma with or without genital bleeding and visible heart rate by ultrasound. Patients were divided into two groups depending on the interruption or continuity of pregnancy: patients who presented spontaneous abortion and patients who continued with their pregnancy after the first trimester. Maternity "Dr. Armando Castillo Plaza" and Hospital "Dr. Urquinaona". Maracaibo, Venezuela. Two hundred patients were selected. The gestational age at the moment of the ultrasound evaluation was 9.2 ± 2.0 weeks and the mean value of subchorionic hematoma volume was 22.4 ± 12.2 cm^sup 3^. The rate of spontaneous abortion in the group was 33.5%. Patients who presented spontaneous abortion did not show significant differences in the maternal age and gestational age at the moment of the ultrasound evaluation compared to those who continued with their pregnancy (p = ns). Patients with spontaneous abortion presented higher mean values of subchorionic hematoma volume (p = 0.05). Relative risk were significant for groups who presented hematomas considered big (relative risk = 1.74; interval confidence 95%, 1.20 - 2.44) and very big (relative risk = 4.19, interval confidence 95%, 2.51 - 7.02; p < 0.05). There is an association between the first trimester subchorionic hematoma volume and an increased risk of spontaneous abortion.