P-341 The effect of endometriosis on implantation success after single embryo transfer of a high-quality euploid blastocyst
Authors: Hernandez P , Gadea B , Mascarós J.M , Muñoz M 
Published: June 2022

Abstract

Study question
Does endometriosis limit the embryo competence to implant in patients undergoing transfer of a single high-quality euploid blastocyst?

Summary answer
Although implantation competence of euploid blastocysts after deferred single-embryo transfers (SET) decreases in endometriosis patients, the effect is not observed when high-quality embryos are transferred.

What is known already
Endometriosis, a frequent gynecological disease, is often associated with female infertility and worse IVF clinical outcomes. Multiple factors may be involved in the subfertility of those patients. Although both defective embryo and altered endometrial receptivity may compromise implantation, evidences suggest a major role of embryo in the endometriosis impaired reproductive outcomes. However, few studies examine implantation after transfer of high-quality euploid embryos. Two studies on this issue suggested that endometriosis does not impact on pregnancy rates but either the embryo morphology was not considered, or a small sample size was used even including transfers with more than one single embryo.

Study design, size, duration
Retrospective multicenter cohort study on the competence of euploid embryos from patients with endometriosis (n = 277) compared with disease-free control women (n = 4677). Implantation and other clinical outcomes (positive pregnancy test, live birth: LB, miscarriages) were examined after SET to ascertain the effect of endometriosis on embryo competence. Results were firstly analyzed in single transferred embryos with any morphological graduation but also when only single high-quality blastocyst (A+B according ASEBIR embryo grading) were transferred.

Participants/materials, setting, methods
Our study involved women aged 18-42 years old undergoing IVF after preimplantation genetic testing for aneuploidies (PGT-A) in IVIRMA Clinics between 2012 and 2019. Severe male factors and patients with altered karyotype or chromosomopathies in previous embryos or pregnancies were excluded. Presence of endometriosis was revealed at the time of surgery or after pelvic ultrasound or NMR. Chi-square test for categorical variables or Student’s-test for quantitative variables were used to assess the statistical significance (P &lt; 0.05).

Main results and the role of chance
A total of 394 euploid blastocyst from endometriosis patients were included in the analysis while 6581 belonged to the control group. Up to 91.5 % were transferred after vitrification-warming in a deferred cycle (338 and 6043 in endometriosis and control groups) while the rest were transferred in the same cycle of embryo biopsy or even the oocyte retrieval. Among the frozen-transferred blastocysts, 76.85% and 74.93% from endometriosis and control women were high-quality embryos on the day of transfer (p = 0.51). Data showed slight but not significant differences in the positive pregnancy test (57.76% vs. 61.37%) and implantation outcomes (49.11% vs. 53.74%) between endometriosis and control group when both frozen and fresh SET were considered. Focusing on deferred SET of euploid blastocysts with any ASEBIR grade, both the proportion of positive test (56.08% vs. 61.82%; p = 0.04) and implanted blastocyst (47.77% vs. 54.34%, p = 0.02) were significantly lower in endometriosis than in the control group. However, they did result in similar amounts of LB (39.14% vs. 43.39%; p = 0.15). Moreover, when the top-quality embryos were examined, none of the clinical outcomes after deferred SET of euploid blastocysts where significantly different between endometriosis and control group (implantation: 50.88% vs. 57.43%; LB: 41.55% vs. 45.60%; p &gt; 0.05).

Limitations, reasons for caution
Results should be interpreted with caution due to the retrospective nature of the study. Although groups were as homogeneous as possible, multivariate regression models to avoid confounding factors are still pending. Reproductive outcomes only after fresh SET or considering to the severity of the disease have not been evaluated yet.

Wider implications of the findings
Although further research is required to surely state no association between endometriosis and embryo reproductive competence, our results suggest a similar pregnancy prognosis in women with or without endometriosis when a high-quality euploid blastocyst is available for transfer. Future prospective studies should take into consideration the quality of the embryo.

Trial registration number
Not applicable