Severe Ovarian Hyperstimulation Syndrome (OHSS) After Gonadotrophin Releasing Hormone Agonist (GnRHa) Triggering

Using a Gonadotrophin Releasing Hormone Agonist (GnRHa) trigger and freezing all eggs or embryos is the most effective strategy for preventing Ovarian Hyperstimulation Syndrome (OHSS) in IVF cycles. The literature predominantly suggests that severe OHSS can virtually be eliminated using the GnRHa trigger. The aim of this study was to determine the clinical characteristics and disease severity of OHSS in patients who received a GnRHa trigger compared to standard Human Chorionic Gonadotropin (HCG) trigger.

Retrospective cohort study of patients with OHSS admitted to a single tertiary referral hospital over a five-year period, from January 2016 to December 2021. HCG and GnRHa trigger cohorts were compared with respect to baseline characteristics, IVF cycle characteristics and OHSS outcomes.

Of 150 cases of severe OHSS requiring admission, 24 (16%) occurred after a GnRHa trigger and 126 (84%) occurred after an HCG trigger. Baseline characteristics were not significantly different. Baseline AMH and the number of oocytes retrieved were significantly higher in the GnRHa group ((69.6 versus 41.4 p < 0.0001) and (28.3 versus 21.7 p = 0.0038) respectively). There was no significant difference in most markers of clinical severity or length of hospital admission.

Using a GnRHa trigger and freeze-all protocol reduces but does not eliminate OHSS in high-risk women. Further preventative strategies may be necessary in this population.