Women who have endometriosis have double the risk of developing inflammatory bowel disease as those without the disorder, according to a Danish study.
The study authors, from the Statens Serum Institut in Copenhagen, add that the effect can remain for up to 20 years after the initial endometriosis diagnosis.
They looked at 37,000 women who had been admitted to hospital with endometriosis between 1977 and 2007.
Over 13 years, 320 women developed inflammatory bowel disease, displaying a 50% increased risk compared with women without the condition.
Looking only at women whose endometriosis had been surgically verified, risk of developing inflammatory bowel disease increased further to 80% and again persisted for 20 years after initial diagnosis.
The authors say that the link may be due to common causes of both disorders or the effects of endometriosis treatment.