The posterior wall expresses different meanings during pregnancy and non-pregnancy; during normal pregnancy, the posterior wall represents the position of the placenta. During non-pregnancy, the posterior wall may refer to the posterior wall of the uterus in general. 1. Placental position: The placenta may be attached to the anterior, posterior and lateral walls of the uterus. It is normal for the placenta to attach to the anterior, posterior and lateral walls of the uterus. This only means that the baby sits in a different position. If the baby sits on the back wall, the baby’s position is usually more backward, so the pregnant mother may feel back pain during pregnancy. 2. The back wall of the uterus: During non-pregnancy, the back wall of the uterus has abnormal echoes in the ultrasound report, which may be fibroids or adenomyomas. If there are abnormalities in the posterior wall, accompanied by menstrual abnormalities and abnormal vaginal discharge, it is recommended to go to the hospital for timely consultation and treatment.