Case report: Two successful pregnancies following the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos

Abstract

Purpose To report successful pregnancies after the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos. Methods and results A total of five day 7 blastocysts developed from vitrified cleaved embryos were re-vitrified and re-warmed. All of five re-vitrified day 7 blastocysts (100%) survived after warming and were transferred to three patients. Two of the women became clinically pregnant. Of these women, one woman delivered a healthy baby and the other pregnancy is ongoing at 26 weeks of gestation. Conclusions This is the first report of successful pregnancies after the transfer of re-vitrified human day 7 blastocysts developed from vitrified cleaved embryos.

Case report: successful delivery following the transfer of a human re-vitrified day-7 spontaneously hatched blastocyst developed from vitrified cleaved embryos

“…In the author's clinical experience, artificial shrinkage of the blastocoele has proved to be effective for increasing the survival rate of vitrified day-5, day-6 and day-7 zona-intact expanded blastocysts [4,15], of vitrified day-5 and day-6 spontaneously hatched blastocysts [19,20] and of re-vitrified day-7 zona-intact expanded blastocysts developed from vitrified cleaved embryos [16]. Therefore, the same vitrification protocol was applied to the day-7 hatched blastocyst, which could be why successful survival of re-vitrified day-7 hatched blastocyst in the present report was observed.…”

“…In our clinical experience, acceptable pregnancy rate of vitrified day-7 zona-intact expanded blastocysts (55%; 6/11) [15], day-5 and day-6 spontaneously hatched blastocysts (75%; 3/4) [20] and re-vitrified day-7 zona intact expanded blastocysts developed from vitrified cleaved embryos (67%; 2/3) [16] was observed following the transfer of these embryos into day-5 endometrium. Thus, the same endometrium preparation was applied to the re-vitrified day-7 hatched blastocyst transfer, which could be why successful implantation of re-vitrified day-7 hatched blastocyst in the present report was obtained.…”

“…On day 3, two fresh cleaved embryos were transferred, but no implantation occurred. The remaining ten day-3 embryos were vitrified by the method developed by Kuwayama et al [3] using a cryotop (Kitazato Supply Co., Fujinomiya, Japan), albeit with slight modifications, and has been described previously [16]. The cryotop consists of a 0.4 mm wide × 20 mm long × 0.1 mm thick polypropylene strip attached to a plastic handle and equipped with a cover straw.…”

“…With the improvement of culture systems and blastocyst cryopreservation techniques, some pregnancies are achieved following the transfer of cryopreserved day-7 zona-intact blastocysts [13][14][15], re-cryopreserved day-7 zona intact blastocysts [16], and day-5 and day-6 spontaneously hatched blastocysts [17][18][19][20]. However, as far as is known, there are no reports on pregnancies following the transfer of re-cryopreserved day-7 spontaneously hatched blastocysts.…”

Impact of the size of zona pellucida thinning area on vitrified-warmed cleavage-stage embryo transfers: a prospective, randomized study

“…The embryos were vitrified by the method developed by Kuwayama et al [18] using a cryotop (Kitazato Supply Co., Fujinomiya, Japan), albeit with slight modifications, and has been described previously [19,20]. The cryotop consists of a 0.4 mm wide×20 mm long×0.1 mm thick polypropylene strips attached to a plastic handle and equipped with a cover straw.…”