Background: Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic and potentially life threatening condition resulting from excessive ovarian stimulation. Reported incidence varies from 1% to 10% of in vitro fertilization (IVF) cycles. The factors contributing to OHSS have not been completely explained. The release of vasoactive substances secreted by the ovaries under human chorionic gonadotrophin (hCG) stimulation may play a key role in triggering this syndrome. This condition is characterised by a massive shift of fluid from the intra-vascular compartment to the third space resulting in profound intra-vascular depletion and haemoconcentration.
Objectives: To assess the effect of withholding gonadotrophins (coasting) on the prevention of ovarian hyperstimulation syndrome in assisted reproduction cycles.
Search strategy: For the update of this review we searched the Cochrane Menstrual Disorders and Subfertility Review Group Trials Register (July 2010), CENTRAL (inception to July 2010), MEDLINE (PubMed) (inception to July 2010), and EMBASE (inception to July 2010) for randomised controlled trials (RCTs) in which coasting was used to prevent OHSS.
Selection criteria: Only randomised controlled trials (RCTs) in which coasting was used to prevent OHSS were included.
Data collection and analysis: Two review authors independently selected trials and extracted data. Disagreements were resolved by discussion. Study authors were contacted to request additional information or missing data. The intervention comparisons were coasting versus early unilateral follicular aspiration (EUFA), no coasting or other interventions. Statistical analysis was performed in accordance with the Cochrane Menstrual Disorders and Subfertility Group guidelines.
Main results: This updated review identified 16 studies of which four met the inclusion criteria. There was no evidence of a difference in the incidence of moderate and severe OHSS (odds ratio (OR) 0.53, 95% CI 0.23 to 1.23), live birth (OR 0.48, 95% CI 0.14 to 1.62; P = 0.24) or in the clinical pregnancy rate (OR 0.69, 95% CI 0.44 to 1.08) between the groups. Significantly fewer oocytes were retrieved in coasting groups compared with GnRHa (OR -2.44, 95% CI -4.30 to -0.58; P = 0.01) or no coasting (OR -3.92, 95% CI -4.47 to -3.37; P < 0.0001). Data for coasting versus EUFA were not pooled for number of oocytes retrieved due to heterogeneity (I(2) = 87%).
Authors' conclusions: There was no evidence to suggest a benefit of using coasting to prevent OHSS compared with no coasting or other interventions.