To make choosing embryo easier - Pre-implantation genetic screening (PGS in Taiwan)
January 07, 2014
How many embryos do you want to transfer? Which embryo do you want to transfer? Many IVF couples just looked down at the records of the frozen embryos with their puzzled faces, and finally decided to ask the technicians to help them to choose the best embryo for them.
According to the released report by Mackay Memorial Hospital in 2013 Annual Meeting of Taiwanese Society of Reproductive Medicine, they found the grading of embryo morphology and the maternal age were two crucial factors to the clinical outcomes through the retrospective study generated by 273 IVF cases recruited from 2009 to 2013. The data has been shown as follows,
Twins | Single | Implantation failure | |
Number of IVF cases (%) | 78 (28.6) | 85 (31.3) | 110 (40.3) |
Age Grading of embryo morphology (Gardner Criteria) | Young ---------------------------- > Old Good ---------------------------- > Poor | ||
Number of retrieved eggs、Concentration of oestrodial /progestosterone、AMH、Thickness of endometrium、Timing of the triggered shot | No significant difference | ||
They scored each embryo as following table, and then they transferred one single blastocyst when the total score was over 90. The rate of multiple birth was successfully reduced to 14.3% from 30% by this way.
Score | 50 | 42 | 35 | 30 | 10 |
Grade | 6AA, 5AA, 4AA | 4AB, 4BA, 4BB | 3AA, 3AB, 3BA, 3BB | 4AC, 4BC, 4CB, 3BC, 3CB | 4CC, 3CC |
Based on this rule, the clinical outcome of single blastocyst transfer (SBT) was displayed,
Number of cases | Clinical pregnancy(%) | Blighted ovum(%) | |
1st FET | 20 | 14 (70.0%) | 3 (21.4%) |
2nd FET | 4 | 3 (75.0%) | 0 (0%) |
Cumulative Pregnancy Rate | ─ | 85.5% | ─ |
FET: Frozen-thawed embryo transfer
In the report released by Stork Fertility Center, we related the effect of the grading of embryo morphology and the maternal age with the chromosomal aneuploidy by the aCGH platform.
(Since 2015, we have shifted our PGS platform from aCGH to NGS, which is more robust in the detection of chromosomal mosaicism and segmental aneuploidy).
(Since 2015, we have shifted our PGS platform from aCGH to NGS, which is more robust in the detection of chromosomal mosaicism and segmental aneuploidy).
1.Trophectoderm cell grading: The chromosomal aneuploid rate was significantly higher in grade C embryo than that of grade A or B.
2. The formation rate of blastocyst: The chromosomal aneuploid rate was significantly higher in D6-formed blastocyst than that of D5-formed blastocyst in the group younger 35 years. In the group older than 35 years, the difference was not that obvious.
In conclusion, to evaluate the quality of a blastocyst, three factors were important －grading of the embryo, maternal age and the formation rate of blastocyst. Nowadays, the PGS (aCGH) has become more ubiquitous before embryo transferring, and it improves the accuracy of choosing not only the "good-looking" one but also "chromosomal normal" one to be transferred.
References:
Trophectoderm grade predicts outcomes of single-blastocyst transfers. Fertility and Sterility. 2013. 99(5): 1283-1289.
PGS is a comparatively new tech for us.
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