Comparison of cryopreservation outcome with human pronuclear stage oocytes obtained by the GnRH antagonist, cetrorelix, and GnRH agonists.

This retrospective study was performed to examine the implantation and pregnancy rates of frozen-thawed pronuclear stage oocytes obtained with the use of a GnRH antagonist, Cetrorelix (Cetrotide((R)) ASTA-Medica, Frankfurt/M, Germany) used in a multidose protocol with hMG, and to compare these results with those obtained after a conventional long GnRH analogue protocol (Decapeptyl-Depot, Ferring, Kiel, Germany). The study population consisted of 31 infertile couples with frozen-thawed pronuclear stage oocytes after ICSI treatment using the GnRH antagonist Cetrorelix (Cetrorelix((R))) and 31 infertile couples with frozen-thawed pronuclear stage oocytes after ICSI treatment using the long GnRH analogue protocol. Patients underwent ICSI after down regulation with a GnRH agonist (Decapeptyl) and stimulation with hMG, or a GnRH antagonist (Cetrorelix) and hMG. The supernumerary pronuclear stage oocytes were cryopreserved and transferred in a later mildly stimulated cycle. The implantation and pregnancy rates for frozen-thawed pronuclear stage oocytes derived from the GnRH antagonist compared with the GnRH agonist were 3.26% versus 3.73% (P=1.0000) and 8.33% versus 10.25% (P=1.0000), respectively. To our knowledge we report here the first pregnancies obtained by the transfer of cryopreserved pronuclear stage embryos generated from ICSI using a GnRH antagonist in the collecting cycle. The use of Cetrorelix in a multiple dose protocol in combination with hMG does not demonstrate a negative effect on viability, implantation potential or pregnancy outcome as compared to 2PN conceptuses obtained from a long GnRH agonist-hMG protocol.