Rescue of corpus luteum function with peri-ovulatory HCG supplementation in IVF/ICSI GnRH antagonist cycles in which ovulation was triggered with a GnRH agonist: a pilot study

Previous studies found a poor clinical outcome when a GnRH agonist (GnRHa) was used to trigger ovulation in GnRH antagonist IVF/ICSI cycles. This study aimed to determine the clinical and endocrine effects as well the optimal timing of HCG supplementation. Forty-five normogonadotrophic IVF/ICSI patients following a flexible antagonist protocol were prospectively randomized (sealed envelopes) to triggering of ovulation with a single bolus of either 10,000 IU of HCG (group 1, n = 15) or 0.5 mg buserelin s.c. In addition, the GnRHa triggered group was randomized into two groups: group 2 ( n = 17) was supplemented with HCG 1500 IU, 12 h after ovulation induction and group 3 ( n = 13) was supplemented with HCG 1500 IU 35 h after ovulation induction. Group 1 and group 3 had significantly higher luteal phase concentrations of progesterone ( P < 0.001) as compared with group 2. Moreover, the clinical pregnancy rate of groups 1 and 3 was similar and significantly higher ( P < 0.02) than that of group 2. A larger study, however, is required to substantiate these differences. No differences were seen regarding mid-luteal inhibin A concentrations between the three groups. Triggering of ovulation with GnRHa supplemented with 1500 IU HCG 35 h later (group 3) seems to secure a normal luteal phase and a normal clinical pregnancy outcome.