OBJECTIVE: To investigate variation in the diagnosis and treatment of chronic endometritis (CE) at the national level in Japan.
METHODS: We performed a nationwide survey targeting all assisted reproductive technology (ART) facilities across Japan between 2021 and 2022. Diagnostic methods, criteria, and first- and second-line treatment protocols for CE were collected via a questionnaire.
RESULTS: Among 616 ART facilities, 437 responded to the survey (response rate: 70.9%) of which 339 (77.6%) implemented diagnosis and treatment of CE. In the diagnosis of CE, 214 (63.1%) facilities used CD138 immunohistochemical staining of endometrial tissue, while hysteroscopy was the most frequently used as an adjunct diagnostic method (241 facilities, 71.1%). The most frequent cutoff value of CD138-positive cells for diagnosing CE was 3-5 cells/20 high-power fields (50%), but 7.9% (17 facilities) and 5.1% (11 facilities) used cutoff values of 1 and 2 cells, respectively. The most common first- and second-line treatment methods were doxycycline (210 facilities, 61.9%) and ciprofloxacin + metronidazole (164 facilities, 48.0%), respectively.
CONCLUSIONS: There is considerable variation in the number of CD138-positive cells used for diagnosing CE. Establishing unified diagnostic criteria and therapeutic methods for CE is essential to provide standardized medicine for CE at the national level.

OBJECTIVE: To investigate the prevalence of chronic endometritis (CE) in infertile patients and whether it affects spontaneous pregnancy after reproductive surgery in infertile patients.
METHODS: In this study, we collected clinical information on infertility patients who underwent reproductive surgery at the Reproductive Medicine Centre of the Second Hospital of Lanzhou University from 2021.1 to 2022.8. All patients underwent laparoscopic and hysteroscopic surgery. Tubal lubrication was performed concurrently with endometrial sample collection and pathological examination. The specimens were immunohistochemically stained with CD38 and CD138, and those who tested positive at the same time were diagnosed with chronic endometritis. As of 2023.9, the patients were followed up by telephone to determine whether chronic endometritis impacted postoperative pregnancy.
RESULTS: A total of 81 patients were finally included in the study. Of these, 25 were in the chronic endometritis group, and 56 were in the non-chronic endometritis group. There were no appreciable differences between the two groups\' demographic statistics. Furthermore, neither the bilateral appendages nor the uterus\'s intraoperative conditions showed a statistically significant difference. Patients in the chronic endometritis group had a longer time to conception from the time of surgery (7 (6.00-11.75) vs. 10 (6.50-16.00), p = 0.467) and a lower rate of spontaneous pregnancies (8/25 = 32.00 % vs. 28/55 = 50.00 %, p = 0.132) than patients with non-chronic endometritis. Among the patients who had successful spontaneous pregnancies after surgery, approximately 77.14 % had live births and 22.86 % had miscarriages, and the live birth rate between the two groups was not significantly different. (21/28 = 75.00 % vs 7/8 = 87.50 %, p = 0.651) CONCLUSION: Chronic endometritis affects approximately 31.82% of infertile patients, and following reproductive surgery, it has no discernible impact on spontaneous pregnancy.

There is limited research on risk factors for chronic endometritis regarding reproductive history and clinical symptoms. Thus, this nested case-control study identified risk factors for chronic endometritis in women who have undergone hysteroscopy. Endometrial tissue sections were obtained from 502 women with intrauterine disorders who underwent hysteroscopy. Chronic endometritis was diagnosed via CD138 immunostaining. The women were divided into two groups: 271 women without chronic endometritis and 231 women with chronic endometritis. The prevalence of chronic endometritis was 46%. Univariate logistic regression revealed that prolonged menstruation and intermenstrual bleeding were associated with chronic endometritis, and subsequent multivariate logistic regression analyses showed that these were further independently associated. With univariable logistic regression, the gravidity and abortion history were correlated with chronic endometritis; however, no significant correlation was found with the adjusted odds ratio (OR) of 0.74 (95% confidence interval [CI] 0.46-1.19) or 0.76 (95% CI 0.58-1.11), respectively. No significant correlation was found between caesarean section history and the rates of chronic endometritis. No significant difference was found in all other variables between the three groups with > 5, ≤ 5 plasma cells and in a unknown group. Prolonged menstruation and intermenstrual bleeding were risk factors associated with chronic endometritis. Chronic endometritis should be considered and CD138 immunohistochemical examination should be recommended in women with these symptoms.

OBJECTIVE: To investigate the impact of antibiotic treatment for chronic endometritis (CE) on the pregnancy outcome of frozen-thawed embryo transfer (FET) cycles and the relevant clinical risk factors associated with CE.
METHODS: A retrospective cohort analysis was conducted on 1352 patients who underwent hysteroscopy and diagnostic curettage at Nanjing Maternal and Child Health Hospital from July 2020 to December 2021. All patients underwent CD138 immunohistochemical (IHC) testing to diagnose CE, and a subset of them underwent FET after hysteroscopy. Patient histories were collected, and reproductive prognosis was followed up.
RESULTS: Out of 1088 patients, 443 (40.7%) were diagnosed with CE. Univariate and multivariate binary logistic regression analyses revealed that parity ≥ 2, a history of ectopic pregnancy, moderate-to-severe dysmenorrhea, hydrosalpinx, endometrial polyps, a history of ≥ 2 uterine operations, and RIF were significantly associated with an elevated risk of CE (P < 0.05). Analysis of the effect of CE on pregnancy outcomes in FET cycles after antibiotic treatment indicated that treated CE patients exhibited a significantly lower miscarriage rate (8.7%) and early miscarriage rate (2.9%) than untreated non-CE patients (20.2%, 16.8%). Moreover, the singleton live birth rate (45.5%) was significantly higher in treated CE patients than in untreated non-CE patients (32.7%). Survival analysis revealed a statistically significant difference in the first clinical pregnancy time between treated CE and untreated non-CE patients after hysteroscopy (P = 0.0019). Stratified analysis based on the presence of recurrent implantation failure (RIF) demonstrated that in the RIF group, treated CE patients were more likely to achieve clinical pregnancy than untreated non-CE patients (P = 0.0021). Among hysteroscopy-positive patients, no significant difference was noted in pregnancy outcomes between the treatment and control groups (P > 0.05).
CONCLUSIONS: Infertile patients with a history of parity ≥ 2, hydrosalpinx, a history of ectopic pregnancy, moderate-to-severe dysmenorrhea, endometrial polyps, a history of ≥ 2 uterine operations, and RIF are at an increased risk of CE; these patients should be recommended to undergo hysteroscopy combined with CD138 examination before embryo transfer. Antibiotic treatment can improve the reproductive outcomes of FET in patients with CE, especially those with RIF.

BACKGROUND: To explore the incidence of chronic endometritis (CE) in patients with infertility and different forms of adenomyosis and analyze potential high-risk factors for infection.
METHODS: This retrospective cohort study included 154 patients with infertility in the Liuzhou Maternity and Child Healthcare Hospital. Among them, 77 patients with adenomyosis were divided into four subgroups based on magnetic resonance imaging (MRI): internal, exterior, intramural, and full-thickness. Meanwhile, 77 patients did not have adenomyosis. Hysteroscopy and endometrial biopsy were performed in the proliferative phase. The main outcome measures were the morphology of the endometrium, syndecan-1 (CD138) immunohistochemical staining, clinical characteristics, and prevalence of CE in the adenomyosis subgroups.
RESULTS: In comparison to the non-adenomyosis group, the adenomyosis group had significantly higher body mass index (BMI) and CA125 levels. The menstrual cycle in the adenomyosis group was significantly shorter, and menarche was significantly earlier. In comparison to the non-adenomyosis group, the adenomyosis group had a significantly higher diagnostic rate of CE (75.3% vs. 46.8% according to hysteroscopy and 74.0% vs. 33.8% according to histopathology, both with p < .050). The incidence of CE was significantly lower in patients with internal adenomyosis when compared with the other three subgroups. Increased BMI contributed to a higher risk of CE.
CONCLUSIONS: The prevalence of CE was significantly higher in patients with adenomyosis and infertility. The differences in the incidence of CE are closely associated with the classification of adenomyosis. When patients with infertility are diagnosed with adenomyosis, it is recommended to identify the subtype and screen for endometritis.

OBJECTIVE: To identify the vaginal microbial signature in women with chronic endometritis (CE) and investigate the potential of vaginal microbiome characterization as a novel diagnostic tools for CE.
METHODS: A cross-sectional study was conducted to compare the characteristics of the vaginal microbiome in 98 women who underwent endometrial biopsy for routine clinical inspection of infertility (49 women diagnosed with CE and 49 with non-CE). The vaginal microbiome was analyzed using 16S ribosomal RNA gene amplicon sequencing. The study included an analysis of diversity, bacterial abundance, and microbial function. In addition, microbial markers were identified, and a CE classifier was developed.
RESULTS: The relative abundances of genera, including Bifidobacterium, Prevotella and Gardnerella, were found to be different between the two groups. Analysis of the Kyoto Encyclopedia of Genes and Genomes pathways reported differential expression in metabolism-related pathways in the two groups. We identified four microbial markers of CE (Enterobacter, Prevotella, Faecalibacterium, and Phascolarctobacterium) and developed a predictive classifier for diagnosing CE, achieving an area under the curve of 83.26%.
CONCLUSIONS: The results of the current study revealed that, compared with the non-CE controls, patients with CE have a different vaginal microbiota, highlighting the diagnostic significance of the vaginal microbiome as a promising noninvasive biomarker in detecting CE.

This study aimed to investigate the effect of diagnosis and treatment of chronic endometritis (CE) on the outcome of assisted reproductive technology (ART) with or without repeated implantation failure (RIF). This retrospective analysis included patients who underwent pathological examination for diagnosis of CE at Yamagata University Hospital. The examination was performed for all patients planned for ART with or without RIF. Patients who were examined within 6 months of the first oocyte retrieval or embryo transfer were included. We counted the number of CD138-positive cells within the endometrial stroma in patients\' specimens and analyzed the patients\' clinical information. Clinical rates of pregnancy and implantation were determined. A total of 80 women met the inclusion criteria: 13 CE-negative patients (17.3%) and 67 CE-positive patients (83.7%). A significant decrease was noted in the CD138-positive cell count between the first biopsy and second biopsy after CE treatment (p < 0.001). In addition, no significant differences were noted in ongoing pregnancy rates between the CE-negative patients and those who underwent CE treatment. The CD138-positive cell counts at first biopsy tended to be lower in each pregnancy group than in the non-pregnancy group. For patients planned to undergo ART, examination for diagnosis of CE with or without RIF could be considered. Pathological CD138-positive cell counts were considered useful for CE diagnosis and treatment decision-making. The study findings suggest the efficacy of antimicrobial agents in CE treatment, contributing to improved pregnancy outcomes.

OBJECTIVE: A review of current knowledge on the pathophysiology, diagnostic and treatment options for chronic endometritis in infertile women.
RESULTS: One of the major causes of failed in vitro fertilization (IVF) is undiagnosed intrauterine pathologies, including chronic inflammation of the uterine mucosa - chronic endometritis. However, some authors relativize the negative impact of chronic endometritis on reproductive outcomes. The etiopathogenesis of chronic endometritis is due to qualitative and quantitative changes in the endometrial microbiome with abnormal multiplication of microorganisms naturally occurring in the uterine cavity or vagina. There is no uniform consensus on the most common pathogen causing chronic endometritis. It is characterized by infiltration of plasma cells into the endometrial stroma outside the menstrual cycle, accompanied by hyperaemia and endometrial oedema. Clinical symptoms are very mild or absent. The diagnosis of chronic endometritis is often difficult because there is no specific clinical or laboratory diagnostic method. The following investigative options are commonly used for the diagnosis of chronic endometritis: diagnostic hysteroscopy, histopathological examination of the endometrium including CD 138 immunohistochemistry and culture from the uterine cavity. However, standardised international hysteroscopic and histopathological criteria for accurate diagnosis of chronic endometritis are still lacking. Empirically administered antibiotic therapy improves the success rate of pregnancy and delivery of a viable foetus in infertile patients with proven chronic endometritis. In addition to reviewing the current knowledge of chronic endometritis, this article discusses the importance of hysteroscopy in the diagnostic process.
CONCLUSIONS: Chronic endometritis is often a clinically silent disease with negative impact on reproduction in infertile women. Although there are still many unresolved issues, the introduction of hysteroscopy into the diagnostic process is important for clinical practice; however, hysteroscopy even in combination with histological examination of the endometrium, often does not allow an unequivocal diagnosis of chronic endometritis. Further prospective randomised studies in a selected group of women with proven chronic endometritis and repeated failure to implant proven euploid embryos should refine this knowledge.

Chronic endometritis (CE) is an inflammatory pathologic condition of the uterine mucosa characterized by unusual infiltration of CD138(+) endometrial stromal plasmacytes (ESPCs). CE is often identified in infertile women with unexplained etiology, tubal factors, endometriosis, repeated implantation failure, and recurrent pregnancy loss. Diagnosis of CE has traditionally relied on endometrial biopsy and histopathologic/immunohistochemistrical detection of ESPCs. Endometrial biopsy, however, is a somewhat painful procedure for the subjects and does not allow us to grasp the whole picture of this mucosal tissue. Meanwhile, fluid hysteroscopy has been recently adopted as a less-invasive diagnostic modality for CE. We launched the ARCHIPELAGO (ARChival Hysteroscopic Image-based Prediction for histopathologic chronic Endometritis in infertile women using deep LeArninG mOdel) study to construct the hysteroscopic CE finding-based prediction tools for histopathologic CE. The development of these deep learning-based novel models and computer-aided detection/diagnosis systems potentially benefits infertile women suffering from this elusive disease.

BACKGROUND: To investigate the impact of chronic endometritis (CE) on the recurrence of endometrial polyps (EPs) in premenopausal women after transcervical resection of endometrial polyps (TCRP).
METHODS: This prospective study enrolled 507 women who underwent TCRP between January 1, 2022 and December 31, 2022. The patients were divided into a CE group (n = 133) and non-CE group (n = 374) based on the expression of CD138 in the endometrium. The EP recurrence rate at 1 year after TCRP was compared between the CE and non-CE groups and between groups with mild CE and severe CE. The impact of CD138 expression by resected EPs on EP recurrence also was investigated.
RESULTS: The EP recurrence rate at 1 year post-TCRP was higher in the CE group than in the non-CE group (25.6% vs. 10.4%) and also higher in the severe CE group than in the mild CE group (34.5% vs. 18.7%). Additionally, the EP recurrence rate was higher among patients with CD138-expressing EPs than among those with EPs lacking CD138 expression (30.5% vs. 6.5%). The odds ratio (OR) for EP recurrence in the CE cohort compared with the non-CE cohort was 3.10 (95% confidence interval [CI] 1.84-5.23) after adjustment for EP number and precautions against EP recurrence. The ORs for EP recurrence in patients with mild CE and severe CE were 2.21 (95%CI 1.11-4.40) and 4.32 (95%CI 2.26-8.26), respectively. Similarly, the OR for EP recurrence in cases with CD138-expressing EPs relative to cases with EPs lacking CD138 expression was 6.22 (95%CI 3.59-10.80) after adjustment for EP number and precautions against EP recurrence.
CONCLUSIONS: CE multiplied the recurrence rate of EPs in premenopausal women after TCRP, and this effect positively correlated with CE severity. CD138 expression by EPs also was associated with a higher risk for EP recurrence.