Symptoms of biochemical pregnancy include abdominal pain in the lower and middle abdomen, vaginal bleeding, and expulsion of endometrial tissue. 1. Biochemical pregnancy is characterized by pain in the middle and sides of the lower and middle abdomen, which is mild to moderate, due to the pain caused by the expelled embryo and uterine contractions. 2. Vaginal bleeding, some patients will experience vaginal bleeding, similar to menstruation, the amount of bleeding varies from person to person. After the expulsion of the embryo and its appendages, the bleeding decreases significantly or stops. 3. Discharge of endothelial tissue, some endothelial tissue may be detached and discharged, but no obvious gestational sac can be seen in the detached tissue. The symptoms of biochemical pregnancy are similar to those of menstruation, so if you suspect a biochemical pregnancy, you should consult a doctor to confirm the diagnosis.