Ovarian hyperstimulation syndrome in the 21st century

PURPOSE OF REVIEW: Ovarian hyperstimulation syndrome (OHSS) complicates a considerable part of stimulated in-vitro fertilization (IVF) cycles and is a potential iatrogenic cause of death in otherwise healthy women undergoing fertility treatment. The triggering factor of OHSS is the widespread use of human chorionic gonadotropin (hCG) to induce final oocyte maturation. The aim of this review is to summarize different approaches available, using alternative triggering protocols such as gonadotropin-releasing hormone agonist (GnRHa) or kisspeptin for final oocyte maturation. RECENT FINDINGS: According to the latest European Society of Human Reproduction and Embryology report, the incidence of OHSS ranges from 0.18 to 1.40% in European countries. However, OHSS is still subject to substantial underreporting. New triggering protocols using GnRHa have shown to be similar to the gold standard hCG-trigger with regard to the reproductive outcome, but with a significant decrease in - and almost elimination of - OHSS. Lately, promising results have been reported for the use of kisspeptin to induce final oocyte maturation. Although until now no study has been performed in an OHSS risk population, theoretically, the risk of OHSS development might be even further reduced after kisspeptin trigger. SUMMARY: GnRHa trigger is currently the best tool we have to prevent OHSS and at the same time maintain good reproductive outcomes. Future research will explore the safety and efficacy of kisspeptin trigger.