COMPARATIVE-STUDY OF THE SURVIVAL RATE OF FROZEN-THAWED EMBRYOS WITH PERFORATED ZONAE FROM MICROSURGICAL FERTILIZATION AND FROZEN-THAWED EMBRYOS WITH INTACT ZONAE

Objective: To compare the survival rate of frozen-thawed embryos with perforated zonae from microsurgical fertilization (subzonal inseminati on) (SUZI) with that of embryos with intact zonae. Design: Thirty-eigh t embryos resulting from microsurgical fertilization by SUZI were cryo preserved in 16 patient cycles. Within the same period, 140 zonae-inta ct embryos from 46 patient cycles were cryopreserved. The survival rat e of the SUZI embryos was compared with the zonae-intact embryos after thawing. Clinical pregnancies were compared after the transfer of the thawed embryos. Results: The total survival rates were 94.7% and 89.3 % for thawed SUZI embryos and zonae-intact embryos, respectively. With in each type of embryo, total survival rates were similar irrespective of the age of the embryos at freezing. The blastomere loss per thawed embryo was the same for zonae-intact and SUZI embryos. One clinical p regnancy was obtained in patients who received thawed SUZI embryos and nine in patients who received embryos with intact zonae. Conclusions: It is concluded that SUZI embryos can be cryopreserved and thawed wit h the same degree of confidence as zonae-intact embryos. The low impla ntation rate of thawed SUZI embryos requires confirmation in a larger clinical series.