Endometriosis screening in patients attending an IVF clinic: a proof-of-concept retrospective cohort study

Given that (i) endometriosis affects approximately 40% of women diagnosed with fertility problems and (ii) this condition may be an underestimated cause of idiopathic infertility, it is essential to identify high-risk patients for laparoscopic screening and reduce the diagnostic delay. We performed a retrospective analysis of 312 women (208 diagnosed with endometriosis and 104 controls) admitted to an in vitro fertilisation (IVF) unit in the city of Brest (France) between June 2007 and July 2014. As part of the women's infertility treatment, levels of cancer antigen 125 (CA-125) were assayed in blood samples collected on the day of oocyte retrieval. Surplus serum was used to set up a new sperm agglutination test. It was observed that sperm agglutination was significantly correlated with endometriosis and CA-125 levels (p < 0.01 for both). By building a decision tree, we identified a subpopulation of patients with low CA-125 levels and a high risk of endometriosis. This proof-of-concept study constitutes a first step towards a high-quality, controlled, multi-centre trial. If our preliminary results are confirmed, the decision tree should improve the medical care given to women in IVF programmes by identifying potential endometriosis sufferers for laparoscopic examination and enabling them to be counselled about precautionary measures.