Endometriosis is a disease in which patches of endometrial tissue,
which normally is found only in the uterine lining (endometrium), grow outside the uterus.
Usually, endometriosis is confined to the lining of the abdominal
cavity or the surface of abdominal organs. The misplaced endometrial tissue (endometrial
implant) commonly adheres to the ovaries and the ligaments that support the uterus. Less
commonly, it adheres to the outer surface of the small and large intestines, the ureters
(tubes leading from the kidneys to the bladder), the bladder, the vagina, surgical scars
in the abdomen, or the lining of the chest cavity. Rarely, endometrial tissue is found in
Because the misplaced endometrial tissue responds to the same hormones
that the uterus responds to, it may bleed during the menstrual period, often causing
cramps, pain, irritation, and the formation of scar tissue. As the disease progresses,
adhesions (fibrous bands that connect normally unconnected structures) may form. The
misplaced endometrial tissue and adhesions can block or interfere with the functioning of
organs. Rarely, adhesions block the Intestine.
Because endometriosis depends on hormonal cycles, and pregnancy
temporarily interrupts those cycles, many women find their symptoms improve during
pregnancy. In some cases, the improvement may be permanent, presumably because the break
from cycles of growth, bleeding, and scarring finally allows the implants to heal and be
shed. In other cases, however, the relief is only temporary, and once the hormonal cycles
return to normal, the symptoms of endometriosis recur.