P-433 Endometrial cavity fluid and clinical pregnancy outcomes in assisted reproduction cycles. A systematic review and meta-analysis
Authors: Salim A , Balachandren N , Kastora S  L , Mavrelos D , Saridogan E 
Published: July 2024

Abstract

Study question
Does Endometrial cavity fluid (ECF) presence affect clinical pregnancy rates in assisted reproduction (ART) cycles? Does ECF aspiration improve clinical pregnancy outcomes?

Summary answer
ECF aspiration appears to improve clinical pregnancy outcomes by 56%.

What is known already
Accumulation of ECF has been a notable finding in ART cycles. The origin of ECF is up to debate; nonetheless, it is frequently associated with a concurrent diagnosis of hydrosalpinx, gonadotropin therapy, subclinical uterine infections, polycystic ovary syndrome amongst other causes. A recent meta-analysis of nine studies highlighted that the presence of ECF substantially diminishes the rates of implantation and clinical pregnancy following embryo transfer, particularly when exceeding 3.5 mm. However, the benefit of ECF aspiration upon clinical pregnancy remains obscure.

Study design, size, duration
The present meta-analysis aimed to compare clinical pregnancy rates between patients with ECF on the day of embryo transfer undergoing ECF aspiration vs. those who did not. The study was conducted according to the PRISMA guidelines. Six databases (Embase, MEDLINE®, APA PsycInfo, Global Health, HMIC Health Management Information Consortium and Google Scholar) and two additional sources were searched from inception to 23rd November 2023.

Participants/materials, setting, methods
Observational and Randomized Control Trials meeting inclusion criteria underwent analysis. Quality assessment for observational studies utilised the ROBINS-I Risk of Bias (RoB) tool, and Cochrane RoB V2 tool was used to assess RCTs. Certainty of evidence was evaluated through the GRADE framework. The Meta-analysis was conducted by computing Odds Ratio (OR), Random Effects (RE) using the Haensel-Mantel method. Summative and subgroup data were analysed via the web-based Cochrane RevMan platform.

Main results and the role of chance
A total of 3 studies were deemed eligible for inclusion, of which 2 were observational (Hou et al., 2022; Hussaini et al., 2018) and a single RCT (Saad et al., 2019). Observational studies were deemed of moderate RoB while the RCT of low RoB. Certainty in overall evidence (GRADE) was deemed moderate. A total of 379 patients were included in the meta-analysis, of a median age 29 [IQR 24.45, 34]. Previous diagnoses of endometriosis, adenomyosis or uterine surgery were not reported in any of the included studies, while only two studies reported the percentage of tubal factor infertile patients in their respective included sample (73% and 25%, Ntotal=125). When aggregately analysed, ECF aspiration resulted in a significant increase in clinical pregnancy rates, OR 1.56 [95% CI 1.04, 2.33], I2= 1%, P = 0.03. Additionally, subgroup analysis of low RoB studies, OR 1.61 [95% CI 1.08, 2.40], I2= 0%, P = 0.02, successfully controlled for heterogeneity whilst also yielding statistically significant results.

Limitations, reasons for caution
Inherent to the nature of observational studies, our meta-analysis suffers from the scarcity of robust randomized control studies and adequately powered observational evidence.

Wider implications of the findings
Our study suggests that ECF aspiration at embryo transfer may improve clinical pregnancy outcomes. However, robust RCTs are required to assess the degree of clinical impact as well as the patient subgroups and their clinical characteristics that may benefit more from such an intervention.

Trial registration number
not applicable