P-322 Chronic endometritis in infertile patients: diagnosis, treatment and follow-up

Abstract Study question Could chronic endometritis treatment have a positive effect on pregnancy outcomes in infertile patients? Summary answer Pharmacological treatment of chronic endometritis (CE) seems to increase the likelihood of spontaneous pregnancy and the success of ART (Assisted Reproductive Techniques) in infertile patients. What is known already Infertility is defined as the inability to conceive after 12 months of unprotected intercourse. A small percentage of infertility is caused by uterine malformations, fibroids, or endometrial infections, such as CE, caused by common microorganisms (Streptococcus, Enterococcus faecalis, etc) Endometritis is defined as an infection or inflammation of the endometrium. Chronic endometritis disrupts endometrial receptivity and contributes to polyabortivity. As it is characterized by a mixed inflammatory infiltrate, plasma cells CD138+ can be a diagnostic marker. The treatment of CE includes oral doxycycline for mildly positive cases and gentamicin combined to corticosteroids for more severe cases. Study design, size, duration Between 2022 and 2023, 414 patients with idiopatic infertility scheduled for ART in a fertility center underwent Vacuum Aspiration Biopsy Random Assay (Vabra) to investigate chronic endometritis. Immunohistochemistry (IHC) for the detection of the plasma cell marker CD138+ on endometrial tissue obtained through VABRA was used for the diagnosis of CE. The aim of the study was to evaluate a possible correlation between pharmacological treatment for chronic endometritis and the achievement of pregnancy. Participants/materials, setting, methods Oral doxycycline was admistered to mildly positive patients (≤ 5 plasma cells CD138+ per 10 HPF), whereas uterine instillation of gentamicin and corticosteroids was usedfor strongly positive (>5 plasma cells CD138+ per 10 HPF). Except in some cases due to the clinical history of patients (polyabortivity, repeated failure of implantation) even the mildly positive were treated with instillation of antibiotic. Two categorical variables were examined: pharmacological treatment for CE and pregnancy after treatment. Main results and the role of chance In the recruited group of 414 patients, 266 (64.25%) were negative for plasma cells CD138+, 72 (17.39%) were strongly positive and 76 (18.36%) were mildly positive. In the strongly positive group 64 patients (89%) were treated with antibiotic instillation: 45% of them obtained pregnancy after embryo transfer and 10% of them got pregnant spontaneously. Only 12% of the non-treated women obtained pregnancy after ET. In the mildly positive group, 10 patients were treated with antibiotic instillation: 50% of them were pregnant after ET. Concurrently, 27 of the mildly positive women took oral doxiciclin: 44% of them obtained pregnancy after ET and 12% got pregnant spontaneously. In the group of 39 patients who received no treatment only 6 (15%) were pregnant after ET. A chi-square test was used to analyse the correlation between pharmacological treatment and pregnancy after treatment. A p-value <0.05 was considered significant. The statistical analysis yielded a p-value of 0.001, indicating a statistically significant correlation between pharmacological treatment (oral or intrauterine instillation) and pregnancy success post-treatment. In a subsequent analysis, the two treatment categories were combined into a single categorical variable, and the results confirmed a statistically significant correlation (p-value = 0.002) between treatment and pregnancy achievement. Limitations, reasons for caution Although IHC is the most reliable method for diagnosing chronic endometritis, no international diagnostic criteria exist. As a consequence there is still not a standardized technique for CD138+ immunostaining of endometrial samples and IHC results can be affected by experimental factors. Additionally, no criteria for plasma cell quantification are available. Wider implications of the findings Further studies should investigate the success of pharmacological treatment depending on the synchrony between the ovarian and uterine cycles. Moreover, it might be beneficial the use of a specific antibiotic targeting the bacterial strain recovered in patients with CE. Trial registration number No