Some of the more uncommon areas that endometriosis can be found are cesarean-section scars, laparoscopy or laparotomy scars; or on the appendix, bladder, bowel, colon, intestines, and rectum.

Endometriosis can also be found, however rarely, inside the bladder, vagina, brain, lung, spine and even on skin.

The cause of endometriosis is unknown. However, some experts think that during menstruation, some of the menstrual tissue flows backward through the fallopian tubes, then implants in the abdomen and grows. They also believe that either an immune system problem or hormonal problem allows this tissue to grow in women who develop endometriosis.

A common symptom for endometriosis is pain, which can sometimes be severe. This pain can be during periods, intercourse or urinating. Pain is usually in the pelvic area, lower abdomen, vagina or back.

Some other symptoms of endometriosis may include:

· Constipation or diarrhea (during menstruation)

· Bleeding from the rectum (during menstruation)

· Bloating (during menstruation)

· Bleeding that is heavy or irregular

· Nausea or vomiting that gets worse before menstruation

· Painful swelling of the belly button

· Fatigue

Infertility is another common symptom of endometriosis. 30-40% of women with endometriosis are estimated to have a reduced ability to conceive. Endometriosis can interfere with ovulation and embryo implantation.

A woman with severe endometriosis can develop adhesions and scar tissue that can cause a deformity inside a woman's body. In extreme cases, the internal organs in the pelvic region can bind together causing a disease called "frozen pelvis."

If endometriosis is detected early on, there are treatments available to preserve fertility. It is also hereditary, so let the doctor know if any of your sisters or mother had this disease.