Endometriosis may occur as nodules below the peritoneal surface, often associated with extensive fibrosis. The pain of endometriosis is said to vary with the menstrual cycle although it can be present to some extent every day. The triad of dysmenorrhoea (pain with menstruation), dyspareunia (pain on intercourse) and non-menstrual pelvic pain is considered characteristic. A diagnosis of endometriosis is more prevalent in the subfertile population than in the general population, and women with diagnosed endometriosis are more likely to suffer difficulties in conceiving than other women. Endometriomas can be readily treated at laparoscopy. The choice of treatment for any particular woman depends very considerably on her plans with regard to fertility or contraception, and her personal preferences regarding the use of hormones and other drugs. Various forms of energy have been used to ablate or excise peritoneal endometriosis, including electrical or laser cautery.