Endometriosis is the result of implantation of menstrual products from the endometrium that are not cleared by the immune system. To determine whether endometriosis is associated with inflammatory bowel disease (IBD) — also an autoimmune-related disorder — investigators in Denmark conducted a nationwide cohort study involving 37,661 women (mean age, 38.6 years) hospitalized with endometriosis during a 40-year period.
During >492,000 person-years of follow-up, the standardized incidence ratio was 1.5 for ulcerative colitis and 1.6 for Crohn disease. The risk for ulcerative colitis was highest among women diagnosed with endometriosis between the ages of 25 and 34. The risk for Crohn disease was highest among women diagnosed before age 25. The mean interval between endometriosis diagnosis and diagnosis of IBD was 10.8 years for ulcerative colitis and 9.8 years for Crohn disease. Risks for IBD remained elevated after >20 years of observation and were even higher when the analysis was confined to women with surgically verified endometriosis.
Comment: These data suggest a shared immunologic basis for endometriosis and IBD. Patients with endometriosis and clinical features associated with IBD should undergo gastrointestinal evaluation.