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Eluate last wash


Okie
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Agree with @donellda. Running the antibody screen on the last wash is all that is necessary. It will show that there is no reactivity verifying adequate washing for the elution procedure, which is why you are testing the last wash.

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22 hours ago, Baby Banker said:

They've never been positive.

That made me think. I must have done many hundreds of elutions and have never seen reactivity in the last wash. Perhaps I was just lucky. I assume someone on this Forum has encountered reactivity in the last wash. Anyone care to share their experience(s) ? What were the circumstances ? What was the patient's diagnosis ? How did you resolve the issue ?

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I was just curious because we used the screen cells for years, and now we've been told to test the whole panel.  Most of us on the bench feel this is wasteful. 

We did have one case where a patient had a previous anti-c and was transfused 10 O Neg RBCs in the ER.  Of course, the majority of those RBCs were c positive, and we never could get the last wash to come up negative.  

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On 6/22/2022 at 10:52 AM, Okie said:

I was just curious because we used the screen cells for years, and now we've been told to test the whole panel.  Most of us on the bench feel this is wasteful. 

We did have one case where a patient had a previous anti-c and was transfused 10 O Neg RBCs in the ER.  Of course, the majority of those RBCs were c positive, and we never could get the last wash to come up negative.  

@Okie, we started doing the whole panel (on the eluate only, not the last wash) because we had an elution CAP survey that had a Di(a) in it. The screen cells, of course, did not pick it up. It was an ungraded challenge but we decided in the long run to perform a full panel on the eluates in case an antibody against a low frequency antigen is causing the positive DAT.

@AuntiS, I'm curious, why are you running Acells and B cells on the last wash? I understand the eluate but I do not see why you would need to ever run more than the screen cells on the last wash.

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On 6/22/2022 at 6:07 AM, exlimey said:

That made me think. I must have done many hundreds of elutions and have never seen reactivity in the last wash. Perhaps I was just lucky. I assume someone on this Forum has encountered reactivity in the last wash. Anyone care to share their experience(s) ? What were the circumstances ? What was the patient's diagnosis ? How did you resolve the issue ?

I've seen it a couple of times. Both were patients with WAIHA who were very actively hemolyzing their own red cells. DATs were 4+++ - like almost didn't need to centrifuge - positive.  Sent both samples to reference lab and neither one could be resolved. I think they tried 12 washes on one sample without success (more than policy, but they were curious to see what would happen). Ugly cases, idiopathic as far as the experts could determine.

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2 hours ago, AMcCord said:

I've seen it a couple of times. Both were patients with WAIHA who were very actively hemolyzing their own red cells. DATs were 4+++ - like almost didn't need to centrifuge - positive.  Sent both samples to reference lab and neither one could be resolved. I think they tried 12 washes on one sample without success (more than policy, but they were curious to see what would happen). Ugly cases, idiopathic as far as the experts could determine.

yep. I've seen that too.

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22 minutes ago, jayinsat said:

yep. I've seen that too.

As have I, but I STILL don't understand the need to try and determine the specificity of an antibody causing a WAIHA, when almost all of them, if not actually all of them, are only mimicking specificities only, and so, to give truly compatible blood would mean giving something like Rhnull units, or En(a-) units - and why would anyone waste such precious units on such a case?  Indeed, as so many were proved to be anti-Rh17 or anti-Rh18, or, indeed, anti-Wrb, why even wasted such rare red cells proving that the wheel has already been invented?  Sorry, but I just don't understand this obsession.

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@AuntiS - as far as running the last wash with A1 and B cells - my thought is that it serves as a negative control for your possible (although VERY unlikely) ABO specific antibodies that may be left.  

We run a panel and A1, B cells with ALL our eluates except cord blood eluates.  For them we run screening cells and x3 A1 or B cells depending on mom/baby ABO incompatibility (we prefer rapid acid over LuiFreeze for cord bloods)

For our last washes we run screening cells and A1,B cells

In the end it comes down to how the protocols are written for each facility.:bow:

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