The most common symptoms of endometriosis are pain and infertility.1
Other common symptoms of endometriosis include:1
- Painful or even debilitating menstrual cramps, which may get worse over time
- Pain during or after sex
- Pain in the intestine or lower abdomen
- Painful bowel movements or painful urination during menstrual periods
- Heavy menstrual periods
- Premenstrual spotting or bleeding between periods2
- Problems getting pregnant3
For some women, the pain associated with endometriosis gets milder after menopause. However, hormone therapy, such as estrogen or birth control pills given to reduce menopausal symptoms, may cause the pain and other symptoms to continue.
Researchers know that pain is a primary symptom of endometriosis, but they do not know exactly what causes the pain.
The severity of the pain does not correspond with the number, location, or extent of endometriosis lesions. Some women with only a few small lesions experience severe pain; other women may have very large patches of endometriosis but experience little pain.1,6
- Patches of endometriosis respond to hormones in a similar way as the lining of the uterus. These tissues may bleed or have inflammation every month, like a regular menstrual period. However, the blood and tissue shed from endometriosis patches stay in the body and are irritants, which can cause pain.
- In some cases, inflammation and chemicals produced by the endometriosis areas can cause the pelvic organs to stick together, causing scar tissue. This makes the uterus, ovaries, fallopian tubes, bladder, and rectum appear as one large organ.
- Hormones and chemicals released by endometriosis tissue may irritate nearby tissue and cause it to release other chemicals that cause pain.
- Over time, some endometriosis areas may form nodules or bumps on the surface of pelvic organs or become cysts (fluid-filled sacs) on the ovaries.
- Some endometriosis lesions have nerves in them, tying the patches directly into the central nervous system. These nerves may be more sensitive to pain-causing chemicals released in the lesions and surrounding areas. Over time, they may be more easily activated by the chemicals than normal nerve cells are.
- Patches of endometriosis might also press against nearby nerve cells to cause pain.
- Some women report less endometriosis pain after pregnancy, but the reason for this is unclear. Researchers are trying to determine whether the pain reduction results from the hormones the body releases during pregnancy or from changes in the cervix, uterus, or endometrium that occur during pregnancy and delivery.
Endometriosis pain can be severe, interfering with day-to-day activities. Understanding how endometriosis is related to pain is a very active area of research because it could allow for more effective treatments for this type of pain.