Case Report: Immediate vs. delayed azithromycin for chronic endometritis: a retrospective cohort study on cure rates and pregnancy outcomes.

Background: Although azithromycin has demonstrated potential therapeutic efficacy in the treatment of chronic endometritis (CE), comprehensive studies on the optimal timing of administration are lacking. Our study aims to evaluate the impact of different timing of azithromycin treatment on cure rates and pregnancy outcomes in patients with CE. Methods: A retrospective cohort study was conducted involving infertile women diagnosed with CE via hysteroscopy during the proliferative phase. Participants with mild CE were assigned to either: immediate treatment (500 mg oral azithromycin daily for 5 days within the same cycle), or delayed treatment (identical treatment dosage and duration in the subsequent cycle). Follow-up endometrial biopsy with CD138 immunohistochemistry was performed during the secretory phase. Cure rates and pregnancy outcomes were compared between the two groups. Results: No significant differences in cure rates were observed between the Immediate treatment group (88.40%) and the delayed treatment group (93.63%) (P > 0.05). The average time from initial diagnosis to follow-up was significantly shorter in the Immediate treatment group (14.80 ± 3.23 days) compared to the delayed treatment group (44.20 ± 7.00 days) (P < 0.0001). Additionally, there were no significant differences in biochemical pregnancy (80.90% vs. 86.39%), clinical pregnancy (70.91% vs. 76.87%), ongoing pregnancy (88.46% vs. 89.38%), or early miscarriage rates (11.54% vs. 8.85%) between the two groups (P > 0.05). To further elucidate the relationship between treatment timing and pregnancy outcomes, we performed multivariate regression analysis. This analysis demonstrated that the different treatment timings for CE were not identified as independent risk factors for biochemical pregnancy [1.44 (0.77-2.68), P = 0.25], clinical pregnancy [1.35 (0.80-2.28), P = 0.264] and ongoing pregnancy [0.83 (0.36-1.88), P = 0.65]. Conclusions: In patients with CE, same-cycle treatment offers the advantage of a significantly shorter follow-up time, which may be beneficial for patients undergoing assisted reproductive technology (ART) cycles. Our analysis confirmed that same-cycle treatment significantly accelerates the entire ART process. Furthermore, although the effect of azithromycin treatment timing in chronic endometritis patients did not reach statistical significance, the observed positive trends of pregnant outcomes justify further investigation with larger sample sizes to determine its clinical efficacy.