2010年11月27日 星期六

胚胎切片可增加試管嬰兒成功率百分之94(ASRM的論文)

胚胎切片可增加試管嬰兒成功率百分之94(ASRM的論文)

http://www.youtube.com/watch?v=GHeW2RpLH74





ASRM: Screening Embryos Boosts IVF Success

By Todd Neale, Staff Writer, MedPage Today
Published: October 26, 2010
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine.
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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.


Note that this study suggests that the use ofquantitative PCR and copy number analysis for screening may significantly improve implantation outcomes.
DENVER -- Preimplantation screening of embryos for an abnormal number of chromosomes resulted in improved outcomes for women undergoing in vitro fertilization, a small randomized trial showed.
Screening, which was performed by taking a single cell from the blastocyst and subjecting it to quantitative PCR, significantly increased implantation rates (76.1% versus 51.8%) and clinical pregnancy rates (94.9% versus 78%) (P<0.05 for both), according to Richard Scott Jr., MD, of Reproductive Medicine Associates of New Jersey in Morristown.

The results, although preliminary, demonstrate that aneuploidy screening can better select embryos for transfer and improve in vitro fertilization outcomes, Scott said at the American Society for Reproductive Medicine meeting here.

And the test may enable greater use of single embryo transfer, which would limit the numbers of multiple births, he said.

Andrew La Barbera, PhD, scientific director of ASRM, explained in an interview that there has been some controversy over use of preimplantation aneuploidy screening because several randomized studies have found no benefit.

But, he said, those studies used FISH (fluorescence in situ hybridization) to evaluate the number of chromosomes. The technique, which involves fixing a nucleus on a microscope slide and staining it with fluorescently labeled markers for various chromosomes, can yield incorrect or inconclusive results because of the possibility that the chromosomes will obscure each other.

Biochemical techniques like the one used by Scott and his colleagues may be a way to improve the accuracy of aneuploid screening.

"It was never that aneuploidy screening didn't make sense; it was only that we didn't have an appropriate technology to allow us to do it effectively," Scott told MedPage Today.

La Barbera echoed Scott's view noting that while the study was preliminary, "it's very promising."

Scott and his colleagues developed a technique for 24 chromosome aneuploidy screening that involved the biopsy of a single cell from the blastocyst on day five of maturation. The DNA was subjected to quantitative PCR and copy number analysis to determine the number of chromosomes. Results are obtained within four hours.

The researchers recruited adult women younger than 43 who had no more than one prior failed cycle of in vitro fertilization for the study, which is ongoing.

All of the patients underwent routine care without restrictions. Embryos were allowed to develop for five days. At that time, the patients were randomized to aneuploidy screening followed by fresh embryo transfer (39 patients) or immediate fresh embryo transfer (41 patients).

The mean age in each group was 33. There were significantly fewer embryos transferred in the screening group (1.8 versus 2.0, P=0.02).

The primary outcome, implantation rate, was significantly better in the screening group (P=0.002).

Rates of chemical pregnancy, clinical pregnancy, and delivered pregnancy were all significantly higher in the screening group (P<0.05 for all).

Despite the lower number of embryos transferred in the screening group, there was a significantly higher rate of twin births (about 70% versus 30%, P=0.002), most likely because of the higher implantation rate, according to Scott.

Although screening with test improved outcomes, there remains the potential for false-abnormal results, which would result in discarding viable embryos, and false-normal results, which would result in implantation of an aneuploid embryo.

In the clinical experience of Scott and his colleagues, there have been more than 970 embryos that were screened as normal and transferred. Of those, three have resulted in abnormal gestations -- one each because of tetraploidy, trisomy 13, and Turner's syndrome -- for an overall clinical error rate of 0.3%.

Scott noted that the test would not reliably detect tetraploidy.

In the future, the test will likely cost patients about $2,500. Scott said that it would add about 15% to 20% to the cost of an in vitro fertilization cycle, but increase the chances of delivering by more than 50%, making the test cost-effective.

The cost benefits would become even more apparent, he said, if the technology can continue to lower the number of embryos that need to be transferred, with the goal of selecting just one embryo. By avoiding multiple births, costs in the millions of dollars in obstetric and pediatric care could be saved, he said.

A cost-effectiveness analysis has not, however, been performed.

Scott reported that he had no conflicts of interest.


Primary source: American Society for Reproductive Medicine

Source reference:
Scott R, et al "A prospective randomized controlled trial demonstrating significantly increased clinical pregnancy rates following 24 chromosome aneuoploidy screening: biopsy and analysis on day 5 with fresh transfer" ASRM 2010; Abstract O-05.

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