Gonadotropin-Releasing Hormone (GnRH) Agonist Trigger in a GnRH Antagonist Protocol and Severe Ovarian Hyperstimulation Syndrome.

Aims: Ovarian hyperstimulation syndrome (OHSS) is an iatrogenic and potentially life-threatening complication of ovarian stimulation. The best strategy to prevent it is to use a gonadotropinreleasing hormone (GnRH) agonist (GnRHa) to trigger final oocyte maturation in a GnRH antagonist protocol, followed by cryopreservation of all oocytes/embryos (freeze-all strategy). The objective of this study is to describe two cases of a rare occurrence of severe OHSS following GnRHa trigger in a GnRH antagonist protocol and freeze-all strategy. Presentation of Case: Two patients (a 33-year-old patient, and a 31-year old patient) were submitted to in vitro fertilization (IVF). The ovarian stimulation started on day 2 of her menstrual cycle in a step-down GnRH antagonist protocol. The final oocyte maturation was induced with a bolus of 0.2 mg triptorelin in both cases. Due tothe risk of OHSS, all the embryos were cryopreserved and no embryo transfer was performed. In the case 1, two days after oocyte retrieval, the patient was seen at the emergency and was diagnosed with severe OHSS with bilateral pleural effusion. In the case 2, three days after oocyte retrieval, the patient was seen at the emergency unit and was diagnosed with severe OHSS. Both patients were managed in an intensive care unit. Conclusions: Unless the substitution of human chorionic gonadotropin (hCG) by GnRHa triggering in antagonist cycles is done in combination with no embryo transfer (which is the best form of OHSS prevention), and unless it virtually completely eliminates the onset of OHSS, this complication may still occur in certain groups of patients.