[tri-med] Re: Amnio Issues

with ashleigh and rj my blood work at 28 weeks came back positive. so we 
went with a level 2 u/s and thay could'nt see anything wrong with either 
child. was asked to have amnio but the change of  losing the baby was high 
so we waited until thay where born, with taylor it came back neg, which it 
should of came neg, but if we had amnio with him it would of told us it was 
triosmy 8 mosaic but we did'nt have it. gina son taylor triosmy 8 mosaic( 
talking about down's with ashleigh and rj) and thay our fine health childern
----- Original Message ----- 
From: "Karen" <karens@xxxxxxxxxxxxxxxx>
To: <tri-med@xxxxxxxxxxxxx>
Sent: Monday, September 25, 2006 12:53 PM
Subject: [tri-med] Re: Amnio Issues



----- Original Message ----- 
From: <TRIER9
> I am fumbling through this discussion. Actually it is about false
> positive's
> for Down syndrome. I know of 1 mom where this happened.....and then  of
> course I was asked HOW does this happen!

A false positive is really uncommon in an amnio - in a CVS its very
possible, not so in an amnio if correct guidelines are followed.

Human error is the most likely problem - remember all karyotypes are done by
human beans.

Not enough cells - possibly but only in the case of mosaicism.

Testing the mothers cells instead of the baby's - not usual in an amnio
because only the first draw could contain contaminant from the mothers skin.
The second draw should have had the mothers cells flushed out. Of course the
operator could have been really bad and taken a sample of the placenta not
the amnion but that should have been visually apparent from the draw.

Placenta has a chromosomal anomaly not the baby - thats very common and is
called confined placental mosaicism. It is usually only detected in a CVS
which takes a sample of the placenta NOT the baby or the amnion. An amnio
should be clear of that.

So my best guess as to why it happens gets back to human error - samples
mixed up along the way (hey it happened to Alex's original blood sample sent
for karyotype) or simply an error in reading the reading the results.
Chromosomal tests are 99.8% accurate - that 0.02% comes from
somewhere...........

Life consists not in holding good cards but in playing those you hold well.
                                            -- Josh Billings

Keep Looking For Rainbows!!
   _--_|\
 /Karen \
 \ _.--._ /
          v Karen, Mum to Alex (11 years, T-18 Mosaic)
http://members.optushome.com.au/karens


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                       www.trisomyonline.org
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