Cycles triggered with GnRH agonist: exploring low-dose HCG for luteal support

The aim of this study in patients at risk of ovarian hyperstimulation syndrome (OHSS) was to determine the efficacy and safety of luteal support using human chorionic gonadotrophin (HCG) after triggering ovulation with gonadotrophin-releasing hormone (GnRH) agonist in IVF/intracytoplasmic sperm injection antagonist cycles. A total of 192 OHSS-risk patients, following a GnRH antagonist protocol (0.25mg/day cetrorelix) during recombinant FSH stimulation, were triggered with 1.5mg s.c. leuproreline for ovulation. A total of three boluses of HCG were used for luteal support, 1000IU (group A, n=44), 500IU (group B, n=115) or 250IU (group C, n=33) every third day, starting the day after oocyte retrieval. For the reproductive outcome, main variables were biochemical and clinical pregnancy rates, and for OHSS, the variables were the numbers of moderate and severe OHSS cases. Overall pregnancy rate was 51.8% and clinical pregnancy rate was 43.4%. This study observed eight cases of moderate (4.2%) and seven of severe OHSS (3.6%). Six out of the seven (85.7%) severe cases were late-onset OHSS, related to pregnancy. In conclusion, GnRH agonist single dose for triggering ovulation and low doses of HCG used as luteal-phase support seem to secure a normal pregnancy outcome without increasing the OHSS risk.