What is endometriosis?

Endometriosis is a chronic condition characterised by growth of endometrial tissue in sites other than the uterine cavity, most commonly in the pelvic cavity, including the ovaries, the uterosacral ligaments, and pouch of Douglas (fig 1).⇓ Common symptoms include dysmenorrhoea, dyspareunia, non-cyclic pelvic pain, and subfertility (table 1).⇓ The clinical presentation is variable, with some women experiencing several severe symptoms and others having no symptoms at all. The prevalence in women without symptoms is 2-50%, depending on the diagnostic criteria used and the populations studied.1 The incidence is 40-60% in women with dysmenorrhoea and 20-30% in women with subfertility.^w1-w3 The severity of symptoms and the probability of diagnosis increase with age.^w4 The most common age of diagnosis is reported as around 40, although this figure came from a study in a cohort of women attending a family planning clinic.^w5 Symptoms and laparoscopic appearance do not always correlate.2 The American Society for Reproductive Medicine has published a classification of severity of endometriosis at laparoscopy.^w6