Effect of the size of zona pellucida opening by laser assisted hatching on clinical outcome of frozen cleaved embryos that were cultured to blastocyst after thawing in women with multiple implantation failures of embryo transfer: a retrospective study

Abstract

Purpose To evaluate the effect of the size of zona pellucida opening by laser assisted hatching for frozen cleaved embryo that were thawed after both fresh and frozen cleaved embryo transfer cycles failed and were cultured to blastocyst after thawing in patients with multiple implantation failures. Materials and methods Of 101 consecutive procedures

Vitrification of human embryos subjected to blastomere biopsy for pre-implantation genetic screening produces higher survival and pregnancy rates than slow freezing

“…Concerns have been raised if embryo biopsy may damage the embryo, leading to a diminution in the viability and implantation potential of both fresh and pre-cryopreserved embryos [33,34,35]. Our findings as well as those of others [36,37] suggest that, with the hand of a skilled operator, no such reduction in embryo viability would be observed. The PR and IR were highest in cases where vitrified blastocysts that had previously undergone blastomere biopsy (37% and 36%) versus those where cryopreserved by conventional freezing (23% and 26%).…”

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

“…In addition, in our previous retrospective study, quarter of zona pellucida thinning by laser assisted hatching significantly increased the rates of pregnancy and implantation in frozen-thawed embryo transfers at the cleavage-stage, compared with controls without assisted hatching (unpublished data). On the other hand, we have recently shown in a retrospective study that half of zona pellucida opening by laser assisted hatching improves pregnancy, implantation and delivery rates of frozen-thawed cleavage-stage embryos that were cultured to blastocyst after thawing and assisted hatching was conducted at the blastocyst-stage, compared with 40 μm (about one eighth of zona pellucida) opening [14]. It is possible that half of zona pellucida thinning in cryopreserved embryo transfer may be associated with higher pregnancy rate than is quarter thinning.…”

Effect of the site of assisted hatching on vitrified-warmed blastocyst transfer cycles: a prospective randomized study

“…(4) The opening of 50 μm probably is not large enough for the hatching process. Large ZP opening (1/2 or 2/3 of the zona diameter) [10,34] or total removal of the ZP [35] resulted in higher delivery rates than partial opening. Whether the possibility of MZT can be reduced by enlarging the opening size or total removal of the ZP needs more clinical data.…”

“…However, there was no international standard protocol for AH technique. The size of the opening [9][10][11], the depth of the micro dissection in ZP [12,13] and the site of AH [14] may all influence the effectiveness of AH. A recent in-vitro observational study of vitrified blastocysts suggested the existence of polarity in the hatching process of human embryos [14].…”