Introduction:

Endometriosis is a condition in which the cells that line the uterus grows outside of the uterus in other areas, such as the ovaries. The condition can interfere with a woman's fertility and ability to become pregnant. Endometriosis can also cause severe pelvic pain, especially during menstruation.

Endometriosis is a common gynecological condition. It is a chronic, painful, and often progressive disease in women. However, the causes of endometriosis are unknown, it is widely variable in symptoms and severity, and it is difficult to diagnose.

Endometrial Implants

Endometriosis occurs when cells from the mucus membrane lining the uterus (endometrium) form implants that attach, grow, and function outside the uterus, generally in the pelvic region.

Endometrial cells contain receptors that bind to estrogen and progesterone, which promote uterine growth and thickening. When these cells become implanted in organs and structures outside the uterus, these hormonal activities continue to occur, causing bleeding and scarring.

Endometriosis is a condition in which cells that normally line the uterus (endometrium) grows on other areas of the body, causing pain and irregular bleeding.

Endometrial implants vary widely in size, shape, and color. Over the years, they may diminish in size or disappear, or they may grow.

• Early implants are usually very small and look like clear pimples.
• If they continue to grow they may form flat injured areas (lesions), small nodules, or cysts called endometriomas, which can range from sizes smaller than a pea to larger than a grapefruit.
• Implants also vary in color; they may be colorless, red, or very dark brown. These so-called chocolate cysts are endometriomas filled with thick, old, dark brown blood that usually appear on the ovaries.

Location of Implants

Implants can form in many areas, most commonly in the following locations in the pelvis:

• Ovaries
• Fallopian tubes
• Uterine surface
• Cul-de-sac, an area between the uterus and rectum
• Bowel
• Bladder
• Rectum
• The peritoneum. This is the smooth surface lining that covers the entire wall of the abdomen and folds over inner organs in the pelvic area.

Rarely, remote sites of endometriosis may include the spinal column, nose, lungs, pelvic lymph nodes, the forearm, and the thigh.

Process of Endometriosis

The process of endometriosis mimics menstruation at certain stages:

• Each month, the exiled endometrial implants respond to the monthly cycle just as they would in the uterus. They fill with blood, thicken, break down and bleed.
• Products of the endometrial process cannot be shed through the vagina as are menstrual blood and debris. Instead, the implants develop into collections of blood that form cysts, spots, or patches.
• Lesions may grow or reseed as the cycle continues.

The lesions are not cancerous, but they can develop to the point that they cause obstruction or adhesions (web-like scar tissue) that attach to and bind together nearby pelvic organs, causing pain, inflammation, and sometimes infertility.

[For more information, see In-Depth Report #100: Menstrual disorders for complete description of female reproductive system and menstrual cycle.]