The Timing of Intracytoplasmic Sperm Injection Relative to Oocyte Retrieval: A Systematic Review and Meta-Analysis

Background: It is currently inconclusive whether different intracytoplasmic sperm injection (ICSI) timings post oocyte retrieval (POR) lead to altered chance of clinical pregnancy and live birth following in vitro fertilization (IVF) treatment. This study, therefore, aimed to synthesize literature-based evidence for better clinical guidance regarding ICSI practice. Methods: A systematic review and meta-analysis were performed according to PRISMA guidelines. Studies were searched for in PubMed, MEDLINE, EMBASE, and the Cochrane Library. Outcome endpoints included clinical pregnancy and live birth rates (LBRs). Results: A total of 605 records were retrieved in the initial search. After exclusion, 30 articles were included for further screening for eligibility. For meta-analysis, 1 prospective and 5 retrospective cohort studies were included for pooled analysis, from which clinical pregnancy rates (CPRs) were evaluated in 6 studies while LBRs were evaluated in 3 studies. CPRs were comparable when ICSI was performed at (a) [Formula: see text] hours POR (risk ratio or RR = 1.00, [Formula: see text] confidence interval [CI] 0.94–1.08) vs [Formula: see text] hours, (b) [Formula: see text] hours (RR = 1.01, [Formula: see text] CI 0.88–1.16) vs [Formula: see text] hours, (c) [Formula: see text] hours (RR = 0.99, [Formula: see text] CI 0.93–1.05) vs [Formula: see text] hours, (d) [Formula: see text] hours (RR = 0.98, [Formula: see text] CI 0.93–1.02) vs [Formula: see text] hours, and (e) [Formula: see text] hours (RR = 1.05, [Formula: see text] CI 0.90–1.23) vs [Formula: see text] hours. However, LBR was reduced when ICSI was performed [Formula: see text] hours POR vs [Formula: see text] hours (RR = 0.94, [Formula: see text] CI 0.89–0.99), but such reduction disappeared when comparing [Formula: see text] hours POR (RR = 1.09, [Formula: see text] CI 0.85–1.38) vs [Formula: see text] hours. Conclusions: CPRs remain comparable when ICSI is performed at a range of timings up to 6-hour POR. However, LBR may benefit slightly by scheduling ICSI between 5- and 6-hour POR.