Stages of endometriosis: Does it affect oocyte quality, embryo development and fertilization rate?

Objective: To investigate the effect of endometriosis and its different stages over Intracytoplasmic Sperm Injection (ICSI) outcomes among infertile women without previous history of ovarian surgery. Methods: A total of 440 women enrolled in ICSI cycles were recruited and divided into two groups: endometriosis (n=220) and control group (n=220). Endometriosis patients without previous surgical treatment and with diagnostic laparoscopy were further stratified based on disease stage. Clinical and laboratory parameters, ovarian reserve markers, the number and quality of oocytes and embryos and fertilization rate were analyzed and compared among the various severity grades of endometriosis and the control group. Results: Patients with advanced endometriosis had significantly fewer retrieved oocytes with small effect size (p<0.001, eta(2)=0.04), lower metaphase II oocytes (p<0.001, eta(2)=0.09) and fewer total numbers of embryos (p<0.001, eta(2)=0.11) compared with less severe disease or women with tubal factor infertility. The fertilization rate in women with severe endometriosis was similar to that of the control group and in those with minimal/mild endometriosis (p=0.187). Conclusions: Severe endometriosis negatively affects ovarian response, oocyte quality and embryos. However, fertilization rate is not different among the various stages of endometriosis.