We performed this retrospective case-control study analyzing 428 first-attempt 
in vitro fertilization (IVF) cycles, among which 254 involved women with a 
previous or present diagnosis of ovarian endometriosis. First, the results of 
these 254 cycles were compared with 174 cycles involving patients with proven 
non-endometriotic tubal infertility having similar age and body mass index. 
Women with ovarian endometriosis had a significantly higher cancellation rate, 
but similar pregnancy, implantation and delivery rates as patients with tubal 
infertility. Second, among the women with ovarian endometriosis, the women with 
a history of laparoscopic surgery for ovarian endometriomas prior to IVF and no 
visual endometriosis at ovum pick-up (n = 112) were compared with the 
non-operated women and visual endometriomas at ovum pick-up (n = 142). Patients 
who underwent ovarian surgery before IVF had significantly shorter period, lower 
antral follicle count and required higher gonadotropin doses than patients with 
non-operated endometriomas. The two groups of women with a previous or present 
ovarian endometriosis did, however, have similar pregnancy, implantation and 
live birth rates. In conclusion, ovarian endometriosis does not reduce IVF 
outcome compared with tubal factor. Furthermore, laparoscopic removal of 
endometriomas does not improve IVF results, but may cause a decrease of ovarian 
responsiveness to gonadotropins.