The optimal length of ‘coasting protocol’ in women at risk of ovarian hyperstimulation syndrome undergoingin vitrofertilization

Abstract

Ovarian hyperstimulation syndrome (OHSS) is a serious and potentially life-threatening complication following ovarian stimulation for in vitro fertilization (IVF). Coasting is the practice whereby the gonadotrophins are withheld and the administration of human chorionic gonadotrophin (hCG) is delayed until serum oestradiol (E₂) has decreased to what is considered to be a safe level, to prevent the onset of OHSS. This study aimed to assess the length of coasting on the reproductive outcome in women at risk of developing OHSS. Coasting was undertaken when the serum E₂ concentrations were ≥17000 pmol/L but 2 measurements were performed and hCG was administered when hormone levels decreased to P < 0.05) and decreased implantation rate (P < 0.05) compared to those coasted for 1 – 3 days. Pregnancy rate/embryo transfer and live birth rate did not differ between groups. In conclusion, coasting appears to decrease the risk of OHSS without compromising the IVF cycle pregnancy outcome. Prolonged coasting is, however, associated with reduced implantation rates, perhaps due to the deleterious effects on the endometrium rather than the oocytes.