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

[miki9]

Hello,


With 8 probe fish, the chromosomes can be damaged more than with a 5 probe fish ?? ???

And if this is correct, then in the test of 8 probe fish may happen that an embryo that is healthy the result is NO healthy (so you have a false negative).


??????????

[nuthinbutpink]

You should NEVER test more than 5 probes with FISH. It is not accurate and the odds of a NT are very high when you wash the cell, start over again and apply more dye to test the additional 3 probes. Nobody here in the US does that anymore because it is very outdated and has been shown not to improve the pregnancy rate. 5 probe for sure!

[miki9]

Nuthinbutpink,

But then why they offer, in **** the 8 probe fish ?? is not logical if you say that is not good?? I don't understand ??

[miki9]

Nuthinbutpink,

What is NT?

[nuthinbutpink]

They are not the most current in the Industry. You'll have to ask them that. There's no way anyone should use more FISH probes than 5. You are doing this for gender not for recurrent pregnancy loss.

FISH has an error rate of 10% per probe. If you use 8, odds are there will be a false positive in the bunch.

FISH is being phased out here, Australia and any other modern medical community. It has been proven not to help pregnancy rates so use as few probes as you can and remember that all you really need to know is gender!

[nuthinbutpink]

No Transfer. They can all test abnormal even though they may be normal due to the known error rate with FISH.

[miki9]

ok thank you very much.

[nuthinbutpink]

FISH is taking a 3D entity and flattening it out to view on a slide. They apply dye to highlight the specific chromosomes. If one chromosome is laying on top of the the other (say 2 chromosome XX), it could look like a single X female and be labeled Turner's when in fact, it could be a totally healthy girl. Any monosomy with FISH has a very high likelihood of being normal IMO. The more probes you use, the higher the chance that this occurs. The other scenario is that the chromosome fails to take the dye and doesn't light up making the cell/embryo seem abnormal.

FISH is totally fine when used properly to identify gender unless the above scenario occurs(not seeing 2 XX). It would be labeled abnormal but no opposite would result.

[miki9]

OK thankyou,

:happy: I will say to the Dr. In **** that I only want an 5 probe fish.

[letibe77]

FISH is taking a 3D entity and flattening it out to view on a slide. ... Any monosomy with FISH has a very high likelihood of being normal IMO. The more probes you use, the higher the chance that this occurs.

FISH is totally fine when used properly to identify gender unless the above scenario occurs(not seeing 2 XX). It would be labeled abnormal but no opposite would result.

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.

Oh, and what do I have to know about
Day 3 or 5 testing (PGD with FISH)? What is good / bad?

Thanks!

[nuthinbutpink]

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!

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.

[letibe77]

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!

[nuthinbutpink]

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.

[letibe77]

Thanks that helps a lot!!!