Endometriosis is a disease in which tissue that normally grows inside the uterus grows outside it.The main symptoms are pelvic pain and infertility. Nearly half of those affected have chronic pelvic pain, while in 70% pain occurs during menstruation. Pain during sex is also common. Infertility occurs in up to half of women affected.Less common symptoms include urinary or bowel symptoms. About 25% of women have no symptoms. Endometriosis can have both social and psychological effects.

The cause is not entirely clear. Risk factors include having a family history of the condition. Most often the ovaries, fallopian tubes, and tissue around the uterus and ovaries are affected; however, in rare cases it may also occur in other parts of the body.The areas of endometriosis bleed each month, resulting in inflammation and scarring. The growths due to endometriosis are not cancer. Diagnosis is usually based on symptoms in combination with medical imaging. Biopsy is the most sure method of diagnosis.[4] Other causes of similar symptoms include pelvic inflammatory disease, irritable bowel syndrome, interstitial cystitis, and fibromyalgia.