When CE was defined as the presence of one or more CD138(+) ESPCs in 15 HPFs (100 × magnification) in three or more sections of eutopic endometrial curettage specimens obtained during the operation, its prevalence was 3.1% in the endometriosis group and 0% in the non-endometriosis group (no statistical difference). This evidence concerns the gene SDC1 and endometriosis.