Will GnRH antagonists provide new hope for patients considered 'difficult responders' to GnRH agonist protocols?

We have assessed the use of cetrorelix, a gonadotrophin releasing hormone (GnRH) antagonist, in conjunction with clomiphene citrate and gonadotrophin in 31 in-vitro fertilization (IVF)/gamete intra-Fallopian transfer (GIFT) cycles for 25 difficult responders. Group I included 18 poor responders (24 cycles) with no live birth in 23 previous IVF:cycles with GnRH agonists, Group II included seven patients (seven cycles) with polycystic ovaries. Thirteen previous IVF/GIFT cycles with GnRH agonists had resulted in one live birth and three of these patients had developed ovarian hyperstimulation syndrome (OHSS). The treatment protocol involved a daily dose of clomiphene citrate 100 mg for 5 days and gonadotrophin injections from cycle day 2. Cetrorelix 0.25 mg/day was started when the leading follicle readied 14 mm, The outcome in both groups was favourable compared to previous treatment with GnRH agonists, In group I the abandoned cycle rate was 29 versus 57% (P = 0.06), More oocytes were produced (6.4 versus 4.7 oocytes/cycle) at a lower dose of follicle-stimulating hormone (FSH) (709 versus 1163 IU/oocyte; P = 0.08) and two live births resulted (11.8%), In group II fewer oocytes were produced (10.2 versus 14.5 oocytes/cycle), using a lower dose df gonadotrophin (170 versus 189 IU/oocyte) and resulted in one ongoing pregnancy. No patients experienced OHSS, This report is preliminary and a further controlled randomized study is required.