Impact of endometriosis on in vitro fertilization and embryo transfer cycles in young women: a stage-dependent interference

OBJECTIVE: Endometriosis is a frequent indication for in vitro fertilization and embryo transfer (IVF-ET). Its influence on IVF-ET cycles remains controversial. We evaluated the impact of the severity of endometriosis on IVF-ET cycles in young women. DESIGN: Retrospective cohort study. SETTING: Academic tertiary referral centre. SAMPLE AND METHODS: In a retrospective cohort analysis, 164 IVF-ET cycles in 148 women with endometriosis-associated infertility were analyzed. Eighty cycles performed during the same period on 72 consecutive women with tubal infertility were considered as controls. All patients were younger than 35 years old. MAIN OUTCOME MEASURES: Response to controlled ovarian hyperstimulation (COH), number of oocytes retrieved, fertilization, implantation and pregnancy rate (PR). RESULTS: Clinical PR was lower in the group with endometriosis (all stages) in comparison with the tubal factor group. Higher total gonadotropin requirements, lower response to COH and lower oocyte yield were also found in the endometriosis group. Stage-stratified analysis showed a lower fertilization rate in stage I-II (52.6% stage I-II, 70.5% stage III-IV and 71.9% tubal factor). In stage III-IV endometriosis there was a higher cycle cancellation rate, a reduced response to COH and a lower PR compared with both the stage I-II and the tubal infertility groups (PR 9.7, 25 and 26.1%, respectively). CONCLUSIONS: Stage III-IV was strongly associated with poor IVF outcome. A decreased fertilization rate in stage I-II might be a cause of subfertility in these women, owing to a hostile environment caused by the disease.