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Patient typed as A neg on Echo 2 months ago, now typing as A pos. Any ideas???


roberman

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2 months ago, a patient came in with just a blood type order. She typed as A neg on the Echo. We didn't do a 2nd type since we only do them on pts receiving products or T&Ss.

Last week she came in for a pre-op T&S and she typed as A pos (3+ with both anti-Ds on the Echo) as well as with tubes. We had her return for a redraw with the same results.

We scrutinzed all the work done on the Echo on that day 2 months ago. We ruled out pt mixups, clerical errors, reagent issues, QC problems, etc. The specimen tube ID had not been hand entered (It was barcode read.), nor had the results been edited.

Thinking it might be WBIT, I pulled the CBC results from both visits to look at indices, plts, etc. The 2 results from 2 months apart were virtually identical.

Her diagnosis was carcinoma in-situ. She was not on chemo and had not had any transfusions during the previous months.

Any ideas??? Thanks!

Robin

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We had a patient with lung cancer several years ago who went from O Neg (weak D negative) to O Positive in 2 months. We never found an explanation. We had transfused her several times previously and never had any problems. It was a gradual strengthening of the anti-D reaction, but we were using tube testing at the time. No change in methodology, reagents, no stem cell transplant...nothing. We initially left her as O Neg and gave her O Neg, but when it reached 3+ we felt like we really couldn't keep calling her O Negative anymore. She eventually reacted 4+ with the anti-D reagent. If you find an explanation, I would love to hear it!

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  • 1 year later...

If its not too late, I would love an update to this if there is any. We are in the very early stages of purchasing an ECHO and I recall from my Gel-Provue days that Rh discrepencies weren't unusual. I am now building 'experience" logs to have on hand as a reference should we run into these situations as we do have an active oncology dept. Thanks

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Had she received any blood product? We've had 2 patients that typed Rh neg on the Echo, but had history of them being Rh pos. On the bench in tube they were 3+. Immucor claims it was because they'd both been transfused Rh negative blood in the previous month. I'm not sure I buy their explanation. I've also noticed that the Anti-D Series 5 stops reacting as well when it gets low in the bottle and sometimes comes up negative when the Series 4 is 2+. 

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I have noticed that Anti-D Series 5 is frequently weaker that Anti-D Series 4 on the ECHO - but I don't think I have seen one that was negative when Series 4 was positive - low bottle or not.  I have noticed lately that both Series 4 and 5 are reacting better than they did during the first 2-3 years that we have had this ECHO.  I don't know whether that reflects reagent changes or some minor tweak that has happened to the ECHO over time as the field engineers get more familiar with the instrument.  The ABORh reaction strenghts are dependent on the "shaking" cycle of the instrument and that could be somewhat individualized in each instrument.

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Had she received any blood product? We've had 2 patients that typed Rh neg on the Echo, but had history of them being Rh pos. On the bench in tube they were 3+. Immucor claims it was because they'd both been transfused Rh negative blood in the previous month. I'm not sure I buy their explanation. I've also noticed that the Anti-D Series 5 stops reacting as well when it gets low in the bottle and sometimes comes up negative when the Series 4 is 2+. 

 

Were any of the donors weakly reactive with anti-D. I had a patient who typed 4+ on the Echo pre-transfusion, received 2 units of RC-LR labeled Rh Pos and post-transfusion typed Rh negative on the Echo and 2+ with anti-D by tube. The donor was very weakly reactive weak D positive - the donation was a double red and my patient got both units.

 

After playing with several sample drawn at different times over 2 days and 4 types of anti-D, I could see some odd things going on with that patient (reaction strengths all over the chart depending on the anti-D and which specimen), so I sent her out for molecular testing. Reference felt that she was probably an uncommon D variant, though they didn't put a name on it - which we would not have detected except for the transfusion with the weak D positive units. Serendipity at work.

Edited by AMcCord
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I do recall a poster presentation at AABB meeting in San Diego in 2011 reporting an unusual ABO typing discrepancy.  Instrument ABO typing differed from manual typing on a multiply transfused patient, where the patient had been transfused with multiple units of ABO compatible but non-identical donor RBC's.  After doing additional testing manually, they noted that if the sample was centrifuged and they sampled from near the bottom of the tube they got donor cells and donor ABO results whereas if they sampled near the top of the red cell layer they got more patient cells and patient ABO type.  You might want to look into where the instrument samples in the height of the tube. 

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I do recall a poster presentation at AABB meeting in San Diego in 2011 reporting an unusual ABO typing discrepancy.  Instrument ABO typing differed from manual typing on a multiply transfused patient, where the patient had been transfused with multiple units of ABO compatible but non-identical donor RBC's.  After doing additional testing manually, they noted that if the sample was centrifuged and they sampled from near the bottom of the tube they got donor cells and donor ABO results whereas if they sampled near the top of the red cell layer they got more patient cells and patient ABO type.  You might want to look into where the instrument samples in the height of the tube. 

Wow! That scenario is something to file away in my brain.

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I do recall a poster presentation at AABB meeting in San Diego in 2011 reporting an unusual ABO typing discrepancy.  Instrument ABO typing differed from manual typing on a multiply transfused patient, where the patient had been transfused with multiple units of ABO compatible but non-identical donor RBC's.  After doing additional testing manually, they noted that if the sample was centrifuged and they sampled from near the bottom of the tube they got donor cells and donor ABO results whereas if they sampled near the top of the red cell layer they got more patient cells and patient ABO type.  You might want to look into where the instrument samples in the height of the tube. 

I have also seen this.   

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But why would you have transfused A+ (current type) to an A= patient (previous type) to create the potential sampling problem.

 

Mass transfusion protocols/trauma protocols - male patients and older/elderly female patients could get Rh pos and maybe type O red cells. Although that is not a likely explanation for the patient in the original post as she had not been recently transfused.

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