APA Dictionary of Psychology

n. a disorder in which the uterine lining (endometrium) is found outside of the uterus, generally in the pelvic region but sometimes as far away as the lungs. The displaced uterine lining follows the same menstrual cycle as the lining within the uterus, including bleeding, which can lead to scarring of nearby organs. Endometriosis may affect up to 10% of women; statistics are inexact because many cases are asymptomatic and therefore undiagnosed. In diagnosed cases, symptoms may include severe pain, excessive bleeding, and dyspareunia. Endometriosis is often associated with infertility. Its cause is unknown. Psychosocial treatments focus on coping with pain, sexual dysfunction, and emotional issues related to infertility.