Eventually adhesions may form. These are rigid, web-like structures of scar tissue that can attach to nearby organs and cause pain, infertility, and intestinal obstruction. The most common problem for women with endometriosis is pain. In severe cases, regular activities may be curtailed for up to two weeks per month. Sleeping problems have been reported in three quarters of patients, mostly due to pain.
Endometriosis causes infertility in a number of ways.
Endometrial cysts or implants in the ovaries or fallopian tubes are particularly likely to cause infertility. Endometrial cysts in the fallopian tubes may block the egg's passage or they may grow in the ovaries and prevent the release of the egg. Sometimes infertility occurs when adhesions form rigid webs of scar tissue between the uterus, ovaries, and fallopian tubes, thereby preventing the transfer of the egg to the tube. Endometriosis can be associated with infertility even if the condition is mild. Some studies have observed poor egg implantation in women with endometriosis.