The effect of chronic endometritis on the clinical outcomes of patients with failure of first embryo transfer

Abstract

Objective: To investigate the effect of chronic endometritis (CE) on the clinical outcomes of patients with failure of first embryo transfer. Methods: A total of 5 605 cycles of frozen-thawed single blastocyst transfer in the reproductive center of the Third Affiliated Hospital of Zhengzhou University from January 2017 to June 2021 were retrospectively collected. After the failure of first embryo transfer, all patients underwent hysteroscopy, and when necessary, endometrial pathology and immunohistochemistry were combined to diagnose CE. Patients were divided into two groups: non-CE group (5 033 cycles) and CE treatment group (572 cycles). The main outcome was live birth rate and the secondary outcomes included clinical pregnancy rate and early abortion rate. The quantitative data were represented by Median (Q1, Q3). The rank sum test was used for comparison between groups. The factors related to live birth rate were analyzed by binary logistic regression model. Results: The incidence of CE was 10.21% (572 cycles) in patients with the failure of first embryo transfer. The maternal age in the non-CE group was 31.0 (29.0, 34.0) years old, and that in the CE treatment group was 31.0 (29.0, 34.0) years old (P<0.001). There was a statistically significant difference in endometrial preparation between the two groups (P=0.010). The endometrial thickness in the CE group was 9.0 (8.2, 10.3) mm on progesterone transformation day, which was higher than that of [9.5 (8.6, 11.0) mm] in the non-CE group (P<0.001). There was no significant difference in clinical pregnancy rate (60.3% (3 035 cycles) vs 63.1% (361 cycles), P=0.193), early abortion rate (17.1% (520 cycles) vs 20.5% (74 cycles), P=0.112) and live birth rate (49.2% (2 477 cycles) vs 49.3% (282 cycles), P=0.969) between the non-CE group and the CE treatment group. The maternal age, endometrial thickness on progesterone transformation day and blastocyst grade were related factors of the live birth rate, and the OR(95%CI) were 0.94 (0.93-0.96), 1.10 (1.06-1.14) and 2.07 (1.84-2.32)), respectively (all P<0.001). Compared with the non-CE group, the CE treatment group did not affect the live birth rate after transplantation, the aOR (95%CI) was 0.99 (0.82-1.18), P=0.882. Conclusions: For patients who underwent the failure of first embryo transfer, hysteroscopy is recommended before single frozen blastocyst transfer, and if necessary, combined with immunohistochemical screening for CE. After standardized treatment, CE patients could obtain similar clinical pregnancy rate, early miscarriage rate and live birth rate as non-CE patients.