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Endometriosis is a painful female disorder in which the inner lining of the uterus grows in other areas of the body. The endometrium, as this tissue lining is called, thickens, dissolves then exits the vagina during the menstrual cycle. When the endometrium is outside the uterus, it becomes stuck and can start to irritate the adjacent organs, according to the National Institutes of Health. This tissue abnormality can cause pain and infertility has effected an estimated 170 million women worldwide, according to endometriosis.org. Luckily, treatment can help alleviate the symptoms and restore fertility.

Overview
When not pregnant, the endometrial tissue lining the uterus breaks down and is shed over the course of each menstrual cycle. Endometriosis occurs when this tissue lining appears elsewhere on the body. When the endometrium breaks down, bloody drops form lesions on the surrounding tissue. Over time, the lesions will begin to bleed internally and grow with each passing menstrual cycle. Women with endometriosis typically have tissue implants on the ovaries, bowel, rectum, bladder, and on the lining of the pelvic area. They can occur in other areas of the body, too, according to the NIH. Lesions that leak can cause adhesions, which leads to painful inflammation and the formation of scar tissue.

Symptoms
Severe pelvic pain is the cardinal sign for endometriosis. This pain tends to worsen over time, and it primarily occurs at particular times in your ovulation cycle. Most women with endometriosis feel pain around or during menstruation. Endometriosis may also cause pain with bowel and bladder movements or during sexual intercourse. Additional symptoms usually occur during menstruation, and they include: diarrhea, constipation, abdominal bloating, heavy vaginal bleeding and fatigue. Women who are having trouble achieving pregnancy may also have endometriosis. According to endometriosis.org, an estimated 30 to 40 percent of women with the disorder are infertile or subfertile.

Cause
There is no known, definitive cause of endometriosis, but researchers suspect retrograde menstruation as the likely culprit, says the MayoClinic. During normal menstruation, blood containing endometrial cells exit the pelvic cavity. Retrograde menstruation is a process whereby menstrual blood flows back into the body instead. The endometrial cells are left in the pelvic walls, eventually creating lesions. The MayoClinic hypothesizes that another cause may be when cells in the abdominal lining mutate into endometrial tissue, due to a genetic mix-up.

Treatment
While there is no final cure for endometriosis, a combination of treatments can effectively manage the condition. Over-the-counter and prescription pain relievers can help ease the symptoms of endometriosis. Although the cause for endometriosis is still unclear, estrogen is known to aggravate its symptoms, says endometriosis.org. Doctors may recommend a counter-balance to oestrogen to prevent menstrual bleeding. Medications that can delay or stop a woman’s period include oral contraceptive pills and progesterone. For severe cases, a surgery may need to be performed. Laparoscopic surgery is a popular method for treating endometriosis. In this procedure, the surgeon uses a telescope-like instrument called a laparoscope to diagnose the disease. If the presence of endometriosis is confirmed, endometrial lesions, adhesions and scar tissue can typically be removed during the same procedure. In very extreme cases, a hysterectomy may need to be performed. This surgical procedure removes the uterus and cervix, and possibly both ovaries. Women who have had a hysterectomy can no longer get pregnant.