**2. Prevalence**

Although endometriosis was originally felt to be a disease only seen in women who had undergone a minimum of 5 years of ovulatory menstrual cycles, it is now well-documented that endometriosis can be seen as early as the premenarchal age group, in girls who have initiated thelarche (63). Prevalence is estimated to be 6–10% in the general female population and 35–50% of the patients experience pain and/or infertility. The prevalence in women without symptoms is 2-50%, depending on the diagnostic criteria used and the populations studied (9). The true incidence of endometriosis in adolescents is difficult to quantify and estimates vary among different studies. The incidence of endometriosis is difficult to quantify, as women with the disease are often asymptomatic, and imaging modalities have low sensitivities for diagnosis. Using this standard, investigators have reported the annual incidence of surgically diagnosed endometriosis to be 1.6 cases per 1,000 women aged between 15 and 49 years (64). The incidence is 40-60% in women with dysmenorrhoea and 20-30% in women with subfertility. According to the Endometriosis Association, 66% of adult women with endometriosis report the onset of pelvic symptoms before age 20, and those who seek care for symptoms as a teen see on average 4 or more physicians before receiving a diagnosis (15).
