Why does surgery for endometriosis-associated infertility often fail to improve pregnancy outcome?

Endometriosis can impair natural reproduction through multiple mechanisms, including distortion of pelvic anatomy and chronic peritoneal inflammation. On this basis, surgical treatment might be reasonably expected to benefit. However, clinical evidence challenges this belief. Surgery can indeed improve natural reproduction, but real benefits are modest. The reasons for the disappointing efficacy of surgery are discussed in this review. They include the presence of 'microscopic' endometriosis, th