Ovary is the most common part of endometriosis, which often makes the ovary adhere to the surrounding fallopian tube, posterior wall of uterus, sigmoid colon and uterine ligament, affecting the blood supply of ovary and the normal peristalsis of fallopian tube.

Some patients with unexplained infertility or mild endometriosis can see purple-blue, purple-brown pigmentation, or flame-like red lesions, or brown patches, or annular peritoneal defects on the pelvic peritoneum. These findings belong to endometriosis. At present, the etiology of endometriosis is not really clear, which may be related to genetic factors, implantation of endometrium after menstrual reflux, lymphatic and venous spread of endometrial debris and changes in immune function. These theories can only explain the occurrence of some endometriosis, and most scholars think it is difficult to explain this disease with one theory.