Endometriosis in association with müllerian anomalies.

There have been many theories proposed regarding etiology and pathogenesis of endometriosis. The theories of retrograde menstruation, celomic metaplasia, and müllerian remnants are among these. In order to find out whether a higher prevalence exists in patients with müllerian anomalies and to test these theories, we reviewed the case records of our reproductive endocrinology clinic set up between 1989 and 1994. The study group included patients with müllerian anomalies (n =186) whereas the control group consisted of patients without müllerian anomalies (n = 3,240). The frequency of endometriosis was 37 of 186 (19.8%) in the study group as compared with 619 of 3,240 (19.1%) in the controls (p > 0.05). In 1 patient without functioning endometrium endometriosis was demonstrated. Obstructive anomalies were associated more with endometriosis as compared with nonobstructive anomalies (p < 0.001). The nonobstructive anomalies did not present a higher prevalence as compared with controls (p > 0.05). These results show that endometriosis is not more frequent in patients with müllerian anomalies as a whole, but outflow obstruction is an important contributing factor. Evaluating patients with müllerian anomalies contributes proof in favor of the theories of retrograde menstruation and celomic metaplasia, but against a possible relation of a developmental defect of differentiation or migration of the müllerian duct system during embryogenesis.