Does follicular flushing increase oocyte number in poor responders? An update of a systematic review

Does flushing of the follicles at ovum retrieval increase the number of retrieved oocytes in poor-response IVF patients?

An update of an electronic literature search was performed to identify randomized controlled trials (RCT) investigating follicular flushing versus no flushing in women with a poor response to IVF treatment. No exclusion criteria for type of needle, stimulation or protocol were applied. A meta-analysis was conducted using the software RevMan 5.4.

Six RCT were identified that had the primary objective of testing for an increase in mean number of cumulus-oocyte complexes or/and metaphase II oocytes between flushing and no flushing. A double-lumen needle was used in five trials, one study investigated a pseudo-double-lumen needle, and a conventional single-lumen needle was used in all the control groups. The main risk of bias in all the included studies is a lack of blinding of the physicians performing the puncture and incomplete data in four trials. A heterogeneity of direction and size of effect of follicular flushing on mean oocyte number retrieved was detected (I² = 80, P = 0.0001), which precludes a synthesis of the data. Two studies showed a decrease or tendency towards a decrease in oocyte numbers, one study showed similar oocyte numbers, and one study showed a strong tendency towards increased oocyte numbers with flushing. A similar picture was seen for metaphase II oocytes (I² = 73, P = 0.002).

It is uncertain whether follicular flushing in poor-response IVF patients affects the number of retrieved oocytes. Larger pragmatic trials are warranted to clarify the effect of flushing on oocyte numbers and clinical outcomes in poor responders and monofollicular patients.