The Prevalence of Incidental Endometriosis in Women Undergoing Laparoscopic Ovarian Drilling for Clomiphene-Resistant Polycystic Ovary Syndrome: A Retrospective Cohort Study and Meta-Analysis

To evaluate the incidence of endometriosis in polycystic ovary syndrome (PCOS) patients who did not present with any endometriosis symptoms and underwent laparoscopic ovarian drilling (LOD) for clomiphene citrate (CC) resistance, 225 and 630 women with CC-resistant PCOS without classic endometriosis symptoms were included in a retrospective study and a meta-analysis, respectively. All women underwent LOD. The main outcome parameter was the prevalence of incidental endometriosis. Laparoscopy revealed endometriosis in 38/225 (16.9%) women (revised American Fertility Society (rAFS) stage I: 33/38, 86.8%; rAFS stage II: 5/38, 13.2%). When women with CC-resistant PCOS without endometriosis were compared, lower body mass index (BMI) and lower 25-hydroxy-vitamin D levels were associated with the presence of endometriosis at laparoscopy (odds ratios (OR): 0.872, 95% confidence intervals (95%CI): 0.792–0.960; p = 0.005 and OR: 0.980, 95%CI: 0.962–0.999; p = 0.036; respectively). The inclusion criteria for the meta-analysis were fulfilled by 4/230 reports about LOD. After correction for study heterogeneity, the pooled prevalence of incidental endometriosis was 7.7% in women with CC-resistant PCOS. In conclusion, the rate of incidental endometriosis in women with CC-resistant PCOS might reflect the prevalence of asymptomatic endometriosis. All cases were affected by minimal or mild disease. Since the literature lacks reports on associated clinical outcomes, the relevance of this entity in such patients should be the subject of further studies.