Comparison of gonadotrophin-releasing hormone analogues and human chorionic gonadotrophin for the induction of ovulation and prevention of ovarian hyperstimulation syndrome: a case-control study.

Gonadotrophin-releasing hormone analogue (GnRHa) has been suggested as an alternative to human chorionic gonadotrophin (HCG) for triggering ovulation, while preventing ovarian hyperstimulation syndrome (OHSS). Since a prospective, controlled study would be unethical at this point, we used a retrospective, case-self control approach to compare GnRHa with HCG in that context. A group of 16 in-vitro fertilization (IVF) patients who had severe OHSS in previous cycles, in which HCG was given to trigger ovulation, were studied in subsequent cycles in which GnRHa was used. Each GnRHa cycle (case) was compared to a previous HCG cycle that resulted in OHSS (self control). None of these subsequent cycles resulted in severe OHSS. The use of GnRHa did not affect the number of oocytes retrieved or their quality. Serum oestradiol concentrations on the day of ovulation triggering were significantly (P < 0.01) higher in the GnRHa cycles compared to HCG cycles. Exogenous progesterone and oestradiol were effective in maintaining relatively constant serum oestradiol and progesterone serum concentrations during the luteal phase. Pregnancy rate per cycle was similar in the two groups. In conclusion, the use of GnRHa to induce ovulation in IVF patients, who are at high risk for developing OHSS, effectively eliminates this risk without affecting other parameters of the stimulation cycle.