Endometriosis reduces ovarian response in controlled ovarian hyperstimulation independent of AMH, AFC, and women's age measured by follicular output rate (FORT) and number of oocytes retrieved.

Purpose: To determine the influence of endometriosis on the ovarian response during controlled ovarian hyperstimulation measured by number of oocytes retrieved and the follicular output rate (FORT).

Methods: A retrospective, single center study included 96 women, who underwent ICSI treatments for male factor infertility according to World Health Organisation between 2016 until 2018. A total of 96 patients were included in the study with 205 fresh ICSI cycles. The study group included 26 patients with endometriosis after surgical and medical treatment; the control group included 70 patients without endometriosis. The women with endometriosis underwent 47 and the control group 158 ICSI cycles. Women underwent fresh intracytoplasmatic sperm injection cycles after controlled ovarian hyperstimulation following a GnRH-antagonist protocol. The FORT was calculated as the ratio of pre-ovulatory follicle count × 100/small antral follicle count at baseline.

Results: A lower number of retrieved oocytes (5.89 vs. 7.25, p = 0.045), lower FORT (75.67 vs. 94.63, p = 0.046), lower number of metaphase II oocytes (4.87 vs. 6.04, p = 0.046), and lower fertilization rate after intracytoplasmatic sperm injection (40.61 vs. 57.76, p = 0.003) were found in women with endometriosis compared to women without endometriosis. The number of oocyctes retrieved was 0.71 lower in the group with endometriosis than in the group without (p = 0.026). The FORT was 24.55% lower in the group with endometriosis (p = 0.025).

Conclusions: Endometriosis reduces the FORT and the number of metaphase-II oocytes after controlled ovarian hyperstimulation independly of women's age, antral follicle count and anti-Müllerian hormone.