Is endometrial receptivity affected in women with endometriosis? Results from a matched pair case-control study of assisted reproductive technology treatments

Research question: Is endometriosis detrimental to embryo implantation? Design: A retrospective matched case-control study of women with a surgical or ultrasound diagnosis of endometriosis at Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico di Milano between 2015 and 2021. Women with endometriosis who underwent a 'freeze-all' cycle during an IVF treatment were eligible to be included. They were matched to patients without the disease, who also underwent cryopreserved blastocyst transfer cycles, in a 1:1 ratio by age (±1 year), and number (=) and quality (±1 top versus low) of cryopreserved blastocysts. All women underwent single frozen embryo transfer, and assisted reproductive technology outcomes suggested by the Core Outcome Measure for Infertility Trials initiative were evaluated. The main outcome was the cumulative live birth rate per cycle. Results: One hundred and one women with endometriosis and 101 matched unaffected women were included. Cumulative live birth rate per cycle did not vary between women with and without endometriosis (50% versus 58%, respectively; P = 0.32). On the basis of the Kaplan-Meier analysis, the predicted success rates over four embryos transferred were also similar (74% versus 82%, respectively; P = 0.67). Conclusion: In women with moderate or severe endometriosis, these retrospective results seem to indicate no or a limited effect of the disease on endometrial receptivity.