Ovarian hyperstimulation syndrome prevention strategies: reducing the human chorionic gonadotropin trigger dose

This article reviews the biological plausibility and evidence for the use of a low triggering dose of human chorionic gonadotropin (hCG) in the prevention of ovarian hyperstimulation syndrome (OHSS). A systematic search of the literature revealed very little published data for or against the use of low-dose hCG in the prevention of OHSS after assisted reproductive technology. We have had success at avoiding OHSS as a result of gentle stimulation and low-dose sliding scale hCG trigger based on estradiol (E₂) levels. We therefore present the biological plausibility for such an approach by reviewing the relationship between OHSS, vascular endothelial growth factor, and hCG; the physiology of hCG; the relationship between risk of OHSS and E₂ at trigger; and the physiology of alternative methods of triggering such as recombinant luteinizing hormone and gonadotropin-releasing hormone agonist. We also present the results of a quasi-experimental before and after study of the sliding scale protocol for hCG trigger dose in in vitro fertilization with or without intracytoplasmic sperm injection cycles.