UNPREDICTABLE CASES OF COMPLICATED OVARIAN HYPERSTIMULATION IN IVF

Objective-To characterize a subpopulation of complicated cases of ovar ian hyperstimulation syndrome (OHSS). Method-Descriptive retrospective study. Results-0.75% of our IVF-ET population suffered from OHSS. Amo ng this group, 33% did not exhibit any recognized risk criteria of OHS S in terms of infertility characteristics and ovarian response to exog enous gonadotrophins. Only severe (ascites) OHSS cases were considered (n = 5) in this study. Previous IVF-ET attempts had been uneventful a nd during the complicated trial, estradiol peak levels and numbers of oocytes retrieved remained below 2,500 pg/mL (conversion factor to SI unit, 3.671) and 10, respectively. In all cases, the luteal phase was supplemented by hCG and all patients became pregnant. A threshold leve l of exogenous and/or endogenous hCG seems to be responsible for the o ccurrence of OHSS. Conclusion-One-third of the patients developing an ovarian hyperstimulation syndrome after IVF-ET had not previously show n risk criteria. A causal role of exogenous and/or endogenous hCG is s uggested.