Abstract: Recurrent spontaneous abortion (RSA) is one of the most important factors of secondary infertility. The incidence of RSA in child-bearing women is 1%~5%. Chronic endometritis (CE) is a persistent inflammation of the endometrium. Patients usually have no clinical symptom, or have only mildly-increased vaginal discharge and menstrual flow, pelvic pain or dysmenorrhea. Therefore, CE is easily overlooked. Histological examination is the gold standard for the diagnosis of CE, which is characterized by the plasma cells in the endometrial stroma. On the basis of traditional HE staining, the CD138 immunohistochemistry can improve the detection rate of CE. CE is a cause of RSA, treatment by antibiotics in those CE patients can improve their pregnancy outcomes. CE has a certain influence on gestation, therefore, it is important to diagnose and treat the potential CE in those RSA patients.

Key words: Chronic disease, Endometritis, Abortion, habitual, Diagnosis, CD138, Syndecan-1