胚胎品質影響冷凍解凍之存活率

胚胎之品質亦影響冷凍解凍之存活率與著床率，
碎片>25%(C, D等級)之胚胎，胚葉blastomere不一致之胚胎，冷凍解凍之存活率較低

http://humrep.oxfordjournals.org/content/22/suppl_1/i9.full.pdf+html?ijkey=585c21253b2644a26b17a7d5cd20dfe24c87f97f&keytype2=tf_ipsecsha


O-023 Oral Single frozen embryo transfer: embryological
prognostic factors
M. Sole´
1
, A. Gomez1
, M. Boada1
, B. Coroleu1
, P. Barri1
, J. Santalo2
, A. Veiga1
1
Institut Universitari Dexeus, Obstetricia-Ginecologia i Reproduccio,
Barcelona, Spain, 2
Departament de Biologia Cel-lular i Fisiologia,
Universitat Autonoma de Barcelona, Barcelona, Spain
Introduction: Pregnancy outcome of frozen embryo transfer (FET) is known
to be related with multiple clinical and embryological factors.
We have focused in the current retrospective study in three essential embryological factors: embryo quality prior to freezing, embryo damage after
thawing and the resumption of mitosis prior to transfer. The purpose of this
study was therefore to evaluate the importance of these factors to select the
best embryo to transfer after thawing.
Material and Methods: A total of 356 no selected single frozen embryo transfers (sFET) were performed during the years 2001–2005 at the Institut Universitari Dexeus. No oocyte donation cycles were included. The mean age (+SD)
of the women at the time of embryo cryopreservation was 35+4,6 years. All
patients involved had their embryos frozen with propanodiol in a slow-freezing
protocol. The majority of 356 embryos were frozen on day 3 (79,8%).
The parameters examined in fresh embryos were cell number, percentage of
cytoplasmic fragmentation and the symmetry of the blastomeres.
After thawing, the embryo was evaluated for the number of surviving blastomeres and then cultured overnight. Just prior to transfer a second evaluation
was performed for the evaluation of mitosis resumption (4 groups were established: blastomere fusion, non-cleaved, one cell cleaved, two cells cleaved and
compactation embryos).
To compare categorical variables chi-square on Fisher exact test was used.
T-test on ANOVA to continuous variables.
Results: The implantation and pregnancy rate (PR) per transfer was 19,9%.
The number of cells at day 3 were related to the PR with embryos with less
than 6 cells showing a decreased PR (9,7% vs. 23,6% with six at least; p,0,05).
Although it seems that there is a relationship between embryo fragmentation
and PR (PR 21,2% when ,25% fragmentation versus PR¼11,4% when
.¼25%) this difference is not statistically significant.
The symmetry of blastomeres was also an important factor. The PR when the
blastomeres were similar or slightly different in size was 34,5% and 26.9%
respectively. A clear reduction in the PR was observed (12,7%; p,0,01)
when blastomeres were different.
The outcome in terms of blastomere survival shows than intact embryos and
embryos with.80% intact blastomeres have similar PR (25,9% and 23,5% respectively). This is significantly higher (p,0,01) than the PR observed when the
survival rate is between 50 and 80% and 50% or less (16,3 and 3,6% respectively).
The degree of blastomere cleavage after overnight culture in the four groups
was also analyzed. PR was 13,4% for embryos with no further cleavage and
15,4% when only one blastomere cleaved. In contrast the PR was significantly
higher (p,0,01) in embryos with cleavage of 2 cells or when compaction was
observed (26,7%).
Conclusions: In order to decrease the multiple pregnancy rates in frozenthawed cycles it is necessary to perform single embryo transfers and to select
the embryo with the highest implantation potential.
Implantation potential has been shown to be related to morphological parameters in the fresh embryo such as the number of cells, the symmetry of the
embryo and their fragmentation. As previously described, the implantation
ability of the frozen-thawed embryos is also correlated with the survival rate.
A high degree of mitosis resumption seems to be necessary to achieve high
implantation rates, with at least two blastomeres showing further cleavage after
overnight culture.
According to our study a frozen-thawed embryo with high implantation
potential has less than 25% of fragmentation, similar or equal blastomeres
prior cryopreservation, with at least a 80% of survival rate and with 2 or
more blastomeres cleaving after thawing and overnight culture.