A condition in which the tissue that lines the uterus grows into the muscular wall of the uterus.

Adenomyosis can lead to an enlarged uterus and painful, heavy periods. The cause of adenomyosis isn't clear. Risk factors include past uterine surgery, childbirth and middle age. Adenomyosis often goes away after menopause.

Adenomyosis symptoms can include heavy or long-lasting menstrual bleeding and serious cramping or sharp pelvic pain during periods. It also can cause ongoing pelvic pain, pain during sex and pressure in the lower stomach area.

Adenomyosis treatment can include medicine to control pain or lessen heavy menstrual bleeding. If treatment doesn't ease serious pain, surgery to remove the uterus might be done. This is called a hysterectomy.