What is the best predictor of severe ovarian hyperstimulation syndrome in IVF? A cohort study.

PURPOSE: The purpose of the present study is to study what is the best predictor of severe ovarian hyperstimulation syndrome (OHSS) in IVF. METHODS: This is a retrospective analysis of all consecutive IVF/intracytoplasmic injection cycles performed during a 5-year period (2009-2014) in a single university fertility centre. All fresh IVF cycles where ovarian stimulation was performed with gonadotrophins and GnRH agonists or antagonists and triggering of final oocyte maturation was induced with the administration of urinary or recombinant hCG were analyzed (2982 patients undergoing 5493 cycles). Because some patients contributed more than one cycle, the analysis of the data was performed with the use of generalized estimating equation (GEE). RESULTS: Severe OHSS was diagnosed in 20 cycles (0.36%, 95% CI 0.20-0.52). The number of follicles ≥10 mm on the day of triggering final oocyte maturation represents the best predictor of severe OHSS in IVF cycles. The cutoff in the number of follicles ≥10 mm with the best capacity to discriminate between women that will and will not develop severe OHSS was ≥15. CONCLUSION: The presence of more than 15 follicles ≥10 mm on the day of triggering final oocyte maturation represents the best predictor of severe OHSS in IVF cycles.