Endometriosis is present in 75% of adolescents with chronic pelvic pain not responsive to medical management. 2/3 of patients with endometriosis say symptoms started before the age of 20 and 21% before the age of 15. 90% of adolescents are more likely to have acyclic pain and non gynecologic symptoms of endometriosis like gastrointestinal and urinary symptoms. 56% of them experience migraines.
(
Reference)