Review question

Cochrane authors sought to assess the safety and efficacy of flushing follicles as part of egg collection in women undergoing interventions to help them get pregnant, termed assisted reproductive technology (ART).

Background

Couples who have difficulty becoming pregnant naturally may choose to have interventions to help them get pregnant. These interventions are known as assisted reproductive technology (ART). One of these interventions is in vitro fertilisation (IVF), or a variant of IVF, called intracytoplasmic sperm injection (ICSI). During IVF, controlled ovarian stimulation uses hormones to stimulate multiple eggs to develop in the ovaries. After ovarian stimulation, a needle guided by ultrasound is used to collect these eggs that are inside follicles. Instead of using only suction to obtain the contents of follicles (aspiration), it has been proposed that flushing the follicles after aspiration may lead to collection of more eggs and higher chances of becoming pregnant and having a baby. This technique is called follicular flushing.

Study characteristics

This review included ten research studies that randomly assigned a total of 928 women to follicular aspiration alone or follicular flushing after aspiration. To see if there was a difference between the two techniques, we wanted to look at the main results of live birth rate (number of babies born per 1000 women) and miscarriage rate (number of miscarriages per 1000 women). We carried out a comprehensive search to identify all relevant research in this field available in July 2017.

Key results

Three studies reported on the main result of live birth rate and noted that follicular flushing probably has little or no effect on live birth rate compared with aspiration alone (moderate-quality evidence). This suggests that if a live birth rate of approximately 41% is seen with aspiration alone, the equivalent live birth rate with follicular flushing is likely to lie between 29% and 52%. None of the included studies reported on the miscarriage rate.

Studies also found that follicular flushing probably makes little or no difference in the number of eggs retrieved, the number of embryos, or the clinical pregnancy rate compared with aspiration alone. Although the quality of evidence was very low, it appears that follicular flushing takes much longer to perform than aspiration alone. Evidence was insufficient to permit any firm conclusions with respect to adverse events or safety.

More research is needed to find out whether any specific patient groups would benefit from follicular flushing.

Quality of the evidence

The quality of evidence for the main outcome of live birth rate was moderate. The quality of evidence for the other outcomes ranged from very low to moderate. The main limitations of included studies were lack of blinding (the process whereby women participating in the trial as well research staff are not aware of the intervention used), inconsistency (differences between different studies), and imprecision (insufficient data).