Case of decidual discharge from the nonpregnant uterine cavity of the bicorporeal uterus before onset of delivery

A 30-year-old woman with a bicorporeal uterus complained of abdominal pain and vaginal hemorrhage at 28 weeks and 5 days of gestation. There were no signs of placenta previa with echography in the second trimester; however, the echography showed a highly echoic area (91 × 85 mm), indicating placenta previa. Thereafter, abdominal pain and vaginal bleeding increased. Thus, we suspected placental abruption and performed cesarean section. After cesarean section, discharge of placenta-like tissue into the vagina was confirmed and pathological examination of the tissue showed only the decidua. In cases of uterine malformations, in which the uterine cavity is divided into pregnant and nonpregnant sides, the decidua on the nonpregnant side can be discharged before the onset of delivery. In addition, at the time of decidual discharge, echography findings are similar to those of placenta previa and the clinical symptoms are similar to those of placental abruption.