Embryo freezing to prevent ovarian hyperstimulation syndrome

One of the primary goals of ART is to achieve some degree of supraphysiologic ovarian stimulation. Too vigorous a response can lead to ovarian hyperstimulation syndrome (OHSS), which is potentially life threatening. The incidence of severe OHSS is low, yet global proliferation of ART suggests that the absolute number of cases will be increasing. The clinical course of OHSS is more severe in patients who conceive. Should gonadotropin therapy induce too great a response, OHSS can best be prevented via cycle cancellation and withholding HCG. An alternative, which would not forfeit oocyte retrieval, is to perform elective cryopreservation of all resulting pre-embryos. This requires a strategy to identify patients at risk accurately. Several centers have bypassed fresh embryo transfer to lessen the risk of OHSS. By consensus it appears that this approach reduces but does not eliminate the risk of severe OHSS. Chances of pregnancy are excellent in subsequent cryo thaw transfers.