Endometriosis is a disease in which the endometrium (the tissue that lines the inside of the uterus or womb) is present outside of the uterus. Endometriosis most commonly occurs in the lower abdomen or pelvis, but it can appear anywhere in the body. Symptoms of endometriosis include lower abdominal pain, pain with menstrual periods, pain with sexual intercourse, and difficulty getting pregnant. On the other hand, some women with endometriosis may not have any symptoms at all.
Approximately 10% of reproductive-aged women have endometriosis. However, the true prevalence is unknown since the diagnosis requires laparoscopy (a surgery where a doctor looks in the abdomen with a camera through the belly button) to visualize and biopsy endometriosis lesions. Endometriosis is seen in 12-32% of women having surgery for pelvic pain, and in up to 50% of women having surgery for infertility. Endometriosis is rarely found in girls before they start their period, but it is seen in up to half of young girls and teens with pelvic pain and painful periods.
Causes of Endometriosis
The exact cause of endometriosis is unknown, but there are several theories that explain how and why endometriosis happens. Retrograde menstruation is one popular theory of its origin in which blood and tissue from a woman’s uterus travel through the fallopian tubes into the abdominal cavity during her period. Nearly all women have some degree of retrograde menstruation, but only a few women will get endometriosis. This may be due to differences in a woman’s immune system.
Another theory of endometriosis origin is called coelomic metaplasia, in which cells in the body outside of the uterus can undergo changes to become cells that line the uterus. This is a common explanation for endometriosis at unusual sites like the thumb or knee. Another possible explanation for endometriosis in locations far from the uterus is that cells from the lining of the uterus travel through blood vessels or the lymphatic system, thereby reaching other distant organs or body areas.
Endometriosis can also spread at the time of surgery. For example, a woman with endometriosis that undergoes a cesarean section could inadvertently have endometriosis implant in the abdominal incision so that she develops endometriosis in the scar from the surgery.
Endometriosis is much more common if a close relative also has the disease, so there may also be genes that influence endometriosis.
When a woman with endometriosis has her period, she has bleeding from both the cells and tissue inside the uterus, and also from the cells and tissue outside the uterus. When blood touches these other organs inside the abdomen, it can cause inflammation and irritation, creating pain. Scar tissue can also develop from the endometriosis and contribute to the pain.
Endometriosis and Fertility
Between 20 and 40% of women with infertility will have endometriosis. Endometriosis likely impairs fertility in two ways: first, by causing distortion of the fallopian tubes so that they are unable to pick up the egg after ovulation, and second, by creating inflammation that can adversely affect the function of the ovary, egg, fallopian tubes or uterus.
Pain is the most common symptom of endometriosis. Women with endometriosis can experience pelvic or lower abdominal pain, pain with menses (dysmenorrhea), pain with intercourse (dyspareunia) and pain during bowel movements (dyschezia). Symptoms can be constant or “cyclical,” meaning that they worsen before and during the period, and then improve. Women may have constant pelvic or lower abdominal pain as well. Other symptoms include infertility, bowel and bladder symptoms (bloating, constipation, blood in the urine, or pain with urination), and possibly abnormal vaginal bleeding.
Some physicians may treat suspected endometriosis based on a woman’s symptoms or physical examination findings to see if they improve without proceeding to surgery. However, to formally diagnose endometriosis, a doctor must perform laparoscopy (surgery in which a doctor looks in the abdomen with a camera through the belly button) to visualize and biopsy suspected endometriosis lesions. Endometriosis lesions can vary in appearance. “Endometrioma” is the term for endometriosis within an ovary, and is often nicknamed “chocolate cyst” because the material inside the cyst looks like chocolate syrup.
The most conservative therapy for endometriosis is with medications. Non-steroidal anti-inflammatory medications, like ibuprofen, may help with the pain associated with endometriosis. Medications that control a woman’s hormones may also help with endometriosis pain. Some examples are oral contraceptive pills and gonadotropin releasing hormone (GnRH) agonists, the latter of which put women into a “temporary” menopause-like state.
Surgery can diagnose endometriosis, and it can also treat endometriosis via removal (excision) or burning (fulguration) of endometriosis lesions. With surgery, removal of scar tissue can alleviate pain and relocate the ovaries and fallopian tubes to their normal position in the pelvis. Surgery has been shown to help some women with endometriosis to become pregnant. If a woman with endometriosis is no longer interested in becoming pregnant, she and her doctor may decide to remove the ovaries and possibly the uterus. A woman cannot become pregnant if she does not have a uterus.
If a woman with endometriosis is having trouble getting pregnant, there are different medications and treatments available that can help her to become pregnant.
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