We have a lady who had a negative antibody screen at booking and 28 weeks (Rh pos to make things easier). She had pre induction bloods taken and came back with a 3+ reaction in cell one only but with a dual population effect. A panel was done and the IAT and enzymes were both negative.

 

A repeat sample was taken and it reacted again on the analyser but this time 3+3+2+ reactivity.

 

The plasma was removed from both samples and hard spun and the resulting plasma yielded negative antibody screens when done manually.

 

The cards on the analsyer don't look like genuine agglutination - there is too clearly defined a gap between the two populations and it looks more like a 4+ reaction MF rather than a 3+ or 2+.

 

We use Ortho and centrifuge at 1000 RCF for 5 minutes to give the correct dilution for the (awkwardly sensitive to TMC issues) analyser. Both samples we tested using the same lot of cards and cells.

 

So my question is - what on earth is going on?

Edited October 2, 20159 yr by Auntie-D

Post delivery samples have now arrived and they are clean as a whistle, negative!

Further update - both prior samples were sent to our sister hospital and came up negative.

 

Stranger...

Fibrin?

Cold ants?  Did you put up a panel in the IgG cards with incubation at RT?

Interference from white cells?

Fibrin?

Cold ants?  Did you put up a panel in the IgG cards with incubation at RT?

Interference from white cells?

 

No to fibrin.

 

We haven't done RT panels - with 3 samples showing different results all taken within 3 hours of each other I couldn't see the point - especially now we know that the samples are negative in our sister lab with the same technology and same batches of reagents. Plus the 3rd (post delivery) sample is negative. Also the reverse group is fine.

 

White cell interference is unlikely as the analsyer samples at the top of the tube, well away from the buffy layer.

Edited October 2, 20159 yr by Auntie-D

What about the wells in your cards?  Any signs of dried gel?

Cold would have been my guess. The sister sample could have been shipped in a cold environment and antibody adsorbed onto cells before testing? But other than that, I got nothing....

I had met specimen showed different reaction in our lab and reference lab, we guess it was because drugs. The drugs concentration  in the patient's  blood will reduce along with  time

But this can not explain why the same specimen got different result in two labs

Cold Antibody: Anti-M?  (Gel is notorious for picking up Anti-M due to it's acidy ... so don't expect duplication with tube.)

 

And Anti-M is so persnickity ... reacts with homozygous-only sometimes, reactive cold-only sometimes, reactive warm sometimes ... and sometimes the screening cells are all M Positive ... temperature of the plasma/gel card/room at time of testing ... etc.

 

We find 'a lot' of Anti-M's on our prenatals ... just a thought to chase down.

 

Have you considered sample contaminated with IV fluid.

Wouldn't an Anti-M or contamination give the same results at our sister lab though?

OK - so let's start from the beginning.  What is wrong with this patient?  Was the patient receiving any fluids at the time of taking the sample?  what were the other results? 

Patient was in labour - 1st sample on admission, 2nd repeat and 3rd post natally. The medics claim she wasn't on any IV infusions and had gone into labour naturally, not induced.

 

All haematology and chemistry results within normal parameters.

 

DCT negative.

DCT????????????????????????

I was sort of looking for the other IH results.  But I've gone back to the original posting.  I am convinced that this was fibrin.  Sorry, but it disappeared when you hard spun the plasma - that is screaming fibrin to me.  Even if it IS an EDTA sample

I agree Anna - especially since it is a pregnancy specimen.  EDTA is not immune to fibrin formation.  That strong mf rx usually shouts anti-M to me but a strong alternative is fibrin in the specimen.

I have seen this before, cold auto.  We did an auto adsorption at 4C, and reran the sample; like yours, clean as a whistle. And I agree with catchmenow51 about the potential adsorption in transport.