"Coasting" (withholding gonadotrophins) for preventing ovarian hyperstimulation syndrome

Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic and potentially life threatening condition resulting from excessive ovarian stimulation. Its reported incidence varies from 1% to 10% of in vitro fertilization (IVF) cycles. The factors leading to this syndrome have not been completely explained. It seems likely that the release of vasoactive substances, secreted by the ovaries under human chorionic gonadotropin (hCG) stimulation plays a key role in triggering this syndrome. The hallmark of this condition, is a massive shift of fluid from the intra-vascular compartment to the third space resulting in profound intra-vascular depletion and hemoconcentration.

The objective of this review is to assess the effect of "coasting" (withholding gonadotrophins) as a preventative strategy in the management of OHSS following superovulation in assisted reproduction treatment on the incidence of all clinical grades of OHSS, in comparison with "early unilateral follicular aspiration (EUFA)" or other interventions.

Publications in the literature that described randomised controlled trials (RCTs) in which "coasting" was used as a preventative strategy to OHSS were included. The Cochrane Menstrual Disorders and Subfertility Review Group specialised register of controlled trials was searched. In addition, MEDLINE (PUBMED) 1985 to 2002, EMBASE (1985 to 2001), CINHAL (1985 to 2001) and National Research Register were also searched.

Randomised controlled trials (RCTs) in which coasting was used as a preventative strategy to OHSS were included.

Two reviewers, Mr N.N. Amso (NNA) and Dr A. D'Angelo (ADA) scanned the titles and the abstracts of the reports identified by electronic searching in order to find relevant papers. One reviewer (ADA) obtained copies of the full text articles and made copies for the other reviewer (NNA) in which details of authors, institution, results and discussion were removed in order to assess their eligibility for inclusion. Then, both reviewers extracted data independently using forms designed according to Cochrane guidelines. Disagreements were resolved by discussion. Additional information on the trial methodology or data were requested by writing twice to the corresponding authors directly. The interventions compared were "coasting" versus "early unilateral follicular aspiration (EUFA)" or no "coasting" or other interventions. Statistical analysis was performed in accordance with the Cochrane Menstrual Disorders and Subfertility Group guidelines.

This review identified thirteen studies but only one trial met our inclusion criteria. There was no difference in the incidence of moderate and severe OHSS (n=30, OR 0.76, 95% CI 0.18, 3.24)and in the clinical pregnancy rate (n=30, OR 0.75, 95% CI 0.17, 3.33) between the groups.

There is a lack of randomised controlled trials for where coasting is compared with no coasting or other interventions such as embryo freezing or intra-venous albumin infusion for prevention of OHSS. There is insufficient evidence to determine if coasting is an effective strategy for preventing OHSS.