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Growing embryos to the blastocyst stage does not necessarily require additional equipment in the lab or highly trained personnel. However, growing [i]good quality[/i] blastocysts does require a higher level of attention to detail than routine culture of embryos to Day 3 and perhaps, some addintional equipment. For example, in a recent post I was singing the praises of tri-gas incubators that decrease the oxygen level surrounding the developing embryos to more closely mimic the conditions in the Fallopian tube. Temperture is another issue. Embryos must be kept at body temperature thought the culture period, including the time the are out of the incubator for observations and manipulation. The correct pH of the culture medium must also be maintained thoughout. For most high volume "factory programs" it is very difficult to maintain these exacting conditions. In addition to a higher level of diligence, it does take more "embryologist hours" because the embryos are in the lab for 2-3 more days. It requires the embryologists work through the weekends (always a popular idea).
Culturing the embyos to the blastocyst stage does not guarantee genetic normalacy. About 20% of blastocysts are genetically abnormal. However, PGD doesn't do much better. Of the maximum of 11 chromosomes (out of 23) they can test, they are able to provide results with an accuracy of about 90%. Genetic abnormalities can also be found in the other 12 chromosomes they do not test for. So, its about a wash. When applied to the general population, PGD does not get you that much farther ahead and its considerable more expensive than blastocyst culture. Take that PGD aficionados! As you might have guessed, I'm not a big proponent of PGD for everyone. However, it is applicable in some specific patient populations.
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