Comparison of cryopreservation outcome with human pronuclear stage oocytesobtained by the GnRH antagonist, Cetrorelix, and GnRH agonists

This retrospective study was performed to examine the implantation and preg nancy rates of frozen-thawed pronuclear stage oocytes obtained with the use of a GnRH antagonist, Cetrorelix (Cetrotide(R) ASTA-Medica, Frankfurt/M, G ermany) used in multidose protocol with hMG, and to compare these results w ith those obtained after a conventional long GnRH analogue protocol (Decape ptyl-Depot, Ferring, Kiel, Germany). The study population consisted of 31 i nfertile couples with frozen-thawed pronuclear stage oocytes after ICSI tre atment using the GnRH antagonist Cetrorelix (Cetrorelix(R)) and 31 infertil e couples with frozen-thawed pronuclear stage oocytes after ICSI treatment using the long GnRH analogue protocol. Patients underwent ICSI after down r egulation with a CnRH agonist (Decapeptyl) and stimulation with hMG, or a G nRH antagonist (Cetrorelix) and hMG. The supernumerary pronuclear stage ooc ytes were cryopreserved and transferred in a later mildly stimulated cycle. The implantation and pregnancy rates for frozen-thawed pronuclear stage oo cytes 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), respe ctively. 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 nega tive effect on viability, implantation potential or pregnancy outcome as co mpared to 2PN conceptuses obtained from a long GnRH agonist-hMG protocol. ( C) 2000 Elsevier Science Ireland Ltd. All rights reserved.