The use of follicle flushing during oocyte retrieval in assisted reproductive technologies: a systematic review and meta-analysis.

study questionDoes follicular flushing during assisted reproductive technologies (ART) improve the number of oocytes retrieved? SUMMARY ANSWER: Follicular flushing during ART does not result in a greater number of oocytes in normal responders. WHAT IS KNOWN ALREADY: Despite limited evidence supporting the use of follicular flushing, it continues to be a common procedure in many ART clinics. Prior studies have provided conflicting results regarding the routine use of flushing during oocyte retrieval. STUDY DESIGN, SIZE, DURATION: Systematic review and meta-analysis of 518 patients who participated in 6 randomized trials over 20 years. PARTICIPANTS/MATERIALS, SETTING,

methodsLiterature searches were conducted to retrieve randomized controlled trials on follicle or ovarian flushing in ART. Databases searched included PubMed, EMBASE, Web of Science and the Cochrane Database of Clinical Trials (CENTRAL). Six trials that included 518 subjects matched the inclusion criteria. Studies included were limited to trials that were published, randomized trials comparing oocyte retrieval with a single-lumen pick-up needle versus follicle flushing after direct aspiration with a multi-channel oocyte pick-up needle in ART patients. MAIN RESULTS AND THE ROLE OF CHANCE: In each of the trials, measures of the oocyte yield (oocytes retrieved divided by follicles aspirated), total oocytes retrieved, fertilization or pregnancy were not different when comparing direct aspiration with follicle flushing. Four trials reported a higher operative time with follicle flushing. Results of the meta-analysis indicated no significant differences in the oocytes retrieved [weighted mean difference: 0.07, 95% confidence interval (CI): -0.13 to 0.29] or the oocyte yield (odds ratio: 1.06, 95% CI: 0.95-1.18) between the non-flushing and flushing groups. LIMITATIONS, REASONS FOR CAUTION: All trials featured an open label design and the majority of patients in this meta-analysis were normal responders. The applications of these results to poor responders, patients undergoing natural cycle ART or minimal stimulation ART should be made with caution. WIDER IMPLICATIONS OF THE

findingsFollicle flushing does not improve ART outcomes in normal-responding patients and should not be performed. This meta-analysis should solidify this recommendation as it includes the largest trial published on the subject and is consistent with a recently published Cochrane review. STUDY FUNDING/COMPETING INTEREST(S): This work was supported, in part, by the Program in Reproductive and Adult Endocrinology, NICHD, NIH, Bethesda, MD. The authors have no competing interests to declare. TRIAL REGISTRATION NUMBER: N/A.