8 PROBE FISH OR 5 PROBE FISH ??? - PGD

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Originally Posted by letibe77

Hi Nuthingbutpink,

you seem to know a lot about the FISH method. Thats great because perhaps you could answer me one more question:
If they tell me for exemple they had 1 abnormal XX embryo, can they test it again (I would pay for that) - just to be sure? Or isn't this possible? I hope you understand what I mean.
Thanks!

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Only if they have day 5 testing capability. They would have to take cells from the trophoblast, the outer layer of the embryo, and assuming they could do that, yes, they could do a rapid FISH test for gender.

It depends what the abnormality was whether or not it is likely to be normal. Any monosomy could retest 100% normal- that is the most common situation.

Thanks for your answer :)
So, did I get it right: if the abnormality is f.e. a trisomy (3x21 or XXX) - then this is a real abnormality? A retest isn't necessary?
But a monosomy (f.e. 1x21 or X) could be a "false negative" A retest could show this?

Thanks!

There is a quoted 10% error rate per probe with FISH.

The monosomy example has just proved itself to be true with FISH and more likely than a trisomy to be normal. I can't answer beyond that because I just don't know.

Unless your clinic performs day 5 biopsies, there will be no retesting. It's not the same as day 3.

Dr Potter retests Natera day 3 abnormals IF it is a single issue on day 3. He does not rebiopsy complex abnormals.

Thanks that helps a lot!!!