Predictors for persistent endometrial cavity fluid from fresh to subsequent frozen embryo transfer

Introduction: During the process of assisted reproductive technology, clinicians are always faced with the problem of endometrial cavity fluid (ECF) interfering with pregnancy outcomes, especially those patients with ECF. The aim of this study was to identify which characteristics of those patients with ECF during the preparation of fresh embryo transfer would predict their recurrent ECF when they were to undergo this cycle of frozen embryo transfer due to cancellation of fresh embryo transfer or failure to obtain a live birth after fresh embryo transfer. Methods: We collected relevant clinical information of those patients receiving assisted reproduction therapy at Reproductive Hospital affiliated with Shandong University between January 2014 and December 2020, including those patients who developed ECF before fresh embryo transfer and canceled fresh embryo transfer for different reasons or did not obtain pregnancy after transfer. Patients were divided into persistent and transient ECF groups according to whether they still had ECF before the current cycle of frozen embryo transfer. We compared relevant data that may influence the persistence of ECF and performed logistic regression analysis to examine whether these variables were associated with the persistence of ECF. Results: The proportion of continued existence of ECF was 14.13% (276/1953). The variables related to the persistence of ECF were as follows: polycystic ovarian syndrome status, previous hysteroscopic adhesiolysis history, history of cesarean section, controlled ovarian hyperstimulation protocol, and endometrial thickness on human chorionic gonadotropin trigger day. Conclusions: It is recommended to inform those patients who present with a thin endometrium on human chorionic gonadotropin trigger day, the diagnosis of polycystic ovarian syndrome, a history of hysteroscopic adhesiolysis, cesarean section history, or were treated with gonadotropin-releasing hormone antagonist protocol that the ECF is less likely to resolve spontaneously, and early intervention based on the corresponding high-risk factors should be recommended.