THE EFFECT OF ENDOMETRIOSIS ON IMPLANTATION - RESULTS FROM THE YALE-UNIVERSITY IN-VITRO FERTILIZATION AND EMBRYO-TRANSFER PROGRAM

Objective: To investigate the effect of endometriosis on implantation. Design: Case-control study from Yale University IVF-ET program. Patie nts: Two hundred eighty-four consecutive IVF cycles were analyzed retr ospectively. Patients with endometriosis only (n = 35; 89 cycles) were compared with an age-matched control group with tubal infertility (n = 70; 147 cycles) and also to a group with unexplained infertility (n = 15; 48 cycles). Data from the endometriosis group was analyzed furth er in subgroups of minimal-mild (43 cycles) and moderate-severe (46 cy cles). Results: No difference was found in the number and the quality of oocytes retrieved and fertilization rates between the endometriosis , the tubal infertility, and the unexplained infertility groups. The q uality and the number of embryos transferred in each group were compar able. A trend toward reduced pregnancy rate per transfer (14.8%) in th e endometriosis versus tubal or unexplained infertility groups (25.7% and 23.3%, respectively) was observed. Implantation rate (gestational sac per transferred embryo) was significantly lower in the endometrios is versus the tubal infertility group (3.9% versus 8.1%; unexplained i nfertility group, 7.2%). Analysis of first cycles only across all grou ps revealed that the implantation rate also was significantly lower in the endometriosis versus the tubal infertility group (3.1% versus 9%; unexplained infertility group, 6.7%). Within the endometriosis group, although the pregnancy rate per cycle and per transfer were similar i n subgroups, patients with minimal-mild endometriosis had the lowest i mplantation rate. Conclusion: We conclude that, in patients with endom etriosis, implantation rate is low. Abnormal implantation, which may h e secondary to endometrial dysfunction or embryotoxic environment, is a factor in endometriosis-associated subfertility.