Risk factors for deep endometriosis: a comparison with pelvic and ovarian endometriosis

Objective: To assess whether deep endometriosis has different risk factors compared with endometriosis at other sites. In epidemiological terms, this should be the case if deep endometriosis represents a different condition than ovarian and peritoneal endometriosis. Design: Case-control study. Setting: University hospitals. Patient(s): The first group of cases included 181 women with a diagnosis of deep endometriosis. The second group of cases included 162 women with endometriosis at other sites. The control group included women younger than 55 years of age who were admitted for acute non-gynecological, non-hormonal, non-neoplastic conditions. Intervention(s): Questionnaire. Main Outcome Measure(s): Odds ratios. Result(s): The age distribution of women with cases of deep and ovarian and pelvic endometriosis was not statistically significantly different. A higher body mass index decreased the risk of both deep as well as ovarian and pelvic endometriosis: the estimated ORs for women reporting a body mass index of ≥21 vs. those reporting a body mass index of <21 were 0.6 (95% confidence interval [CI], 0.3–0.8) for deep endometriosis and 0.6 (95% CI, 0.4–0.9) for pelvic and ovarian endometriosis. Parous women were at decreased risk: in comparison with nulliparae, the odds ratio for deep endometriosis was 0.1 (95% CI, 0.1–0.2) for women reporting one or more births. The corresponding value for pelvic and ovarian endometriosis was 0.1 (95% CI, 0.1–0.2). Conclusion(s): This study suggests that deep as well as ovarian and pelvic endometriosis share similar risk factors.