Those at highest risk of OHSS including patients with > 20 follicles or peak serum E2 > 4000 pg/ml, may be candidates for GnRH agonist trigger alone and freeze all oocytes or embryos, since such patients may have a higher incidence of significant OHSS after low dose adjuvant hCG use [21, 34]. This evidence concerns the gene GNRH1 and ovarian hyperstimulation syndrome.