Continuation of GnRH Agonist Administration for 1 Week, After HCG Injection, Prevents Ovarian Hyperstimulation Syndrome Following Elective Cryopreservation of All Pronucleate Embryos

Background: An approach consisting of elective cryopreservation of all embryos has been proposed for patients at risk of ovarian hyperstimulation syndrome (OHSS). Although elective cryopreservation can prevent pregnancy-induced late OHSS, it cannot prevent early OHSS. Early OHSS is reported to have been complicated with thromboembolism. The study was carried out to assess the efficacy with which the continued administration of GnRH agonist for 1 week after 5000 IU of hCG injection could prevent early OHSS.

Methods: This study employed an open controlled clinical trial at three centres for treatment of infertility in Sapporo. A total of 138 patients at risk of OHSS during IVF-embryo transfer from January 1, 1998 to December 31, 1999, were assigned in turn either to a group with elective cryopreservation of all pronucleate embryos (n = 68) or to one with continuation of GnRH agonist administration for 1 week after hCG injection following elective cryopreservation (n = 70). Subsequently, they were transferred in hormone replacement cycles. The development of severe OHSS (ascites, haemoconcentration) was compared between the two groups.

Results: A total of 10% of patients developed severe OHSS necessitating hospitalization because of a marked increase in ascites in the upper abdomen and the haemoconcentration in the elective cryopreservation alone group. On the other hand, none developed severe OHSS in the GnRH agonist continuation group.

Conclusions: In our study, continuation of GnRH agonist for 1 week after hCG injection prevented severe early OHSS following elective cryopreservation of all embryos. This treatment is safe and cost-beneficial, and should be performed promptly for patients at risk of OHSS.