Comparison of diagnostic tests for chronic endometritis and endometrial dysbiosis in recurrent implantation failure: Impact on pregnancy outcomes

Chronic endometritis (CE) and endometrial dysbiosis (ED) are major causes of recurrent implantation failure (RIF). CE is diagnosed via hysteroscopy or the endometrial CD138 test; ED is examined using endometrial microbiome testing with next-generation sequencing. ED is characterized by a reduction in Lactobacillus species. However, correlations between the results of the three tests and the efficacy of treatment against CE and ED in pregnancy outcomes remain unclear. We analyzed 73 patients with RIF who underwent all three tests (hysteroscopy, endometrial CD138 test, and endometrial microbiome test). Patients with CE received antibiotics, whereas those with ED received antibiotics and vaginal Lactobacillus probiotics. The incidences of CE diagnosed using hysteroscopy and the CD138 test were 56.2 and 49.3%, respectively, and the prevalence of ED was 53.4%. No correlations were observed among the test-positive individuals in these three tests. Among patients with ED, 88.9% had a post-treatment clinical pregnancy, a significantly higher rate than that in patients without ED (p = 0.021). Multivariate analysis demonstrated that ED was associated with clinical pregnancy (odds ratio (OR): 6.29, p = 0.031). In conclusion, the three tests detected different populations of patients with RIF. ED diagnosed using the endometrial microbiome test was associated with favorable pregnancy outcomes after testing.