Supernumerary ovary on recto-sigmoid colon with associated endometriosis

A supernumerary ovary is a rare gynecological anomaly, and is usually excised due to its malignant transformation potential. We report a case of a supernumerary ovary and endometriosis situated on the anterior rectosigmoid colon. When laparoscopy was conducted, a firm, 5-cm mass was discovered on the anterior rectosigmoid colon along with normal ovaries. In this case, the discovery of a supernumerary ovary implied the presence of endometriosis. It is unusual for endometriosis and a supernumerary ovary to exist simultaneously.