I-13: Blastocyst Culture and Freezing
نویسنده
چکیده مقاله:
It should now be beyond doubt that blastocyst culture results in better pregnancy rate (PR). This calls for fewer embryos to be transferred, and indeed blastocyst culture is of most value when the intention is to put back one embryo at a time. The PR with one top-grade blastocyst is 45-65% in different studies. If two top-grade blastocysts are transferred, the PR usually does not differ, but the rate of multiples increases manyfold. Given a good freezing programme, the cumulative PR after one fresh and one frozen single blastocyst transfer exceeds that of a fresh two-blastocyst transfer. Culture can be done open, or in drops under oil. The use of a low-oxygen (”three-gas”) incubator is beneficial. ET shall be performed on day 5. PR decreases if fresh ET is done on day 6, but embryos frozen on day 5 or day 6 perform equally when transferred in a freeze-thaw cycle. Preferrably, this should be a spontaneous or a FSH stimulated cycle. Oestrogen / progesteron cycles may result in a higher rate of miscarriages. Only top-grade or next to top-grade blastocysts should be frozen to ensure good results. The fact that there are fewer day 5 embryos to be frozen than after 2-3 days culture is an advantage rather than the opposite, as the PR per embryo is higher. Puncturing of the expanded blastocyst is crucial and can be done just as well with a needle as by laser. Most studies have shown that vitrification is superior to slowfreezing, but these studies often have surprisingly poor results for slow-freezing with low surviving rates and low PR. At our unit, 76% of thawed blastocysts survive and are transferred with a PR after transfer of a single blastocyst of 56%, which is the same as the comparable fresh transfer. Where three or more embryos are transferred, there is no advantage of blastocyst culture. Indeed, it only results in even more multiple pregnancies.
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عنوان ژورنال
دوره 6 شماره 2
صفحات -
تاریخ انتشار 2012-09-01
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