Follicular flushing during oocyte retrieval in assisted reproductive techniques.

backgroundFollicular aspiration under transvaginal ultrasound guidance is routinely performed as part of assisted reproductive technology (ART) to retrieve oocytes for in vitro fertilisation (IVF). The process involves aspiration of the follicular fluid followed by the introduction of flush, typically culture media, back into the follicle followed by re-aspiration. However, there is a degree of controversy as to whether this intervention yields a larger number of oocytes and is hence associated with greater potential for pregnancy than aspiration only.

objectivesTo assess the safety and efficacy of follicular flushing as compared with aspiration only performed in women undergoing ART. SEARCH

methodsWe searched the following electronic databases up to 13 July 2021: the Cochrane Gynaecology and Fertility Specialised Register of Controlled Trials, CENTRAL (containing output from two trial registries and CINAHL), MEDLINE, Embase, and PsycINFO. We also searched LILACS, Google Scholar, and Epistemonikos. We reviewed the reference lists of relevant papers and contacted experts in the field to identify further relevant studies. SELECTION CRITERIA: We included randomised controlled trials (RCTs) that compared follicular aspiration and flushing with aspiration alone in women undergoing ART using their own gametes. Primary outcomes were live birth rate and miscarriage rate per woman randomised. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed studies identified by search against the inclusion criteria, extracted data, and assessed risk of bias. A third review author was consulted if required. We contacted study authors as needed. We analysed dichotomous outcomes using Mantel-Haenszel odds ratios (ORs), 95% confidence intervals (CIs), and a fixed-effect model, and we analysed continuous outcomes using mean differences (MDs) between groups presented with 95% CIs. We examined the heterogeneity of studies via the I MAIN

resultsWe included 15 studies with a total of 1643 women. Fourteen studies reported outcomes per woman randomised, and one study reported outcomes per ovary. No studies were at low risk of bias across all domains; the main limitation was lack of blinding. The certainty of the evidence ranged from moderate to very low, and was downgraded for risk of bias, imprecision, and inconsistency. We are uncertain of the effect of follicular flushing on live birth rate compared to aspiration alone (OR 0.93, 95% CI 0.59 to 1.46; 4 RCTs; n = 467; I AUTHORS'

conclusionsThe effect of follicular flushing on both live birth and miscarriage rates compared with aspiration alone is uncertain. Although the evidence does not permit any firm conclusions on the impact of follicular flushing on oocyte yield, total number of embryos, number of cryopreserved embryos, or clinical pregnancy rate, it may be that the procedure itself takes longer than aspiration alone. The evidence was insufficient to permit any firm conclusions with respect to adverse events or safety.