Follicular flushing at oocyte retrieval: a reappraisal

Abstract

A survey of Australian assisted reproduction technique (ART) units revealed many (> 50%) use flushing of the follicle in addition to direct aspiration of the fluid during oocyte retrieval. The rationale is that flushing offers an advantage to the patient, with a larger number of oocytes being collected and thus a higher potential for pregnancy Following a complication in a patient, the medical staff determined that flushing might have been implicated. While this was later shown to be unfounded, the unit changed the method of oocyte collection, thus providing an opportunity historically to evaluate the differences between aspiration of follicular fluid alone or with additional flushing of each follicle. Thus the aim of this analysis was to test the hypothesis that aspiration alone does not effect the outcomes of ART with respect to oocyte numbers collected, their quality and subsequent fertilisation, or ultimate pregnancy rate in a large patient group (n = 2378). During the review period (1991-1993) the manufacturer of the aspiration needles; the pump and pressure used for aspiration; the staff involved in all procedures; and the premises, equipment and media used for oocyte collection and culture remained constant. Similarly the two patient groups did not differ in their demographics and physical characteristics. There was no difference (p > 0.5) in the number of oocytes collected, the number of embryos created or the pregnancy rate for that treatment cycle. There was also no significant difference between the two groups in fertilisation rates, irrespective of the type of treatment being used in vitro fertilisation (IVF), gamete intrafallopian transfer (GIFT) or intracytoplasmic sperm injection (ICSI)). The data presented in this paper are not prospective. They use historical comparison and are confounded by minor changes in ovarian stimulation protocols, but the conclusions are still valid. These data suggest there is no difference in the outcome of ART (from oocyte collection through to pregnancy rate) whether or not aspiration of follicles is accompanied by flushing. First principles of surgery advocate the shortest possible operating time, the simplest procedure and minimum amount of tissue handling as maxims for reducing complication. Therefore, as a routine, flushing would seem superfluous in ART.