I didn't want to hijack the thread (Elution Studies) that prompted this one....

I couldn't help but notice the number of responses that stated an eluate would be made out to three months in the patient who was transfused within that time period or pregnant during said time frame.

If any of you have any statistics that support this practice, I'd love to see them.  I found a study where eluates were being performed out to one month on patients with positive DATs and in that instance, the authors reported only a 0.6% rate of finding an antibody that was not already detected in the patient's serum/plasma.  In following their parameters, it cost them $9000+ to find that one sample and concluded that the benefit vs cost was not justified.

The Technical Manual references Judd et al. (The evaluation of a positive direct antiglobulin test (autocontrol) in pretransfusion testing revisited.  Transfusion 1986;26:220-4) when it states: "For transfusion reactions, newly developed antibodies that are initially detectable only in the eluate are usually detectable in the serum after about 14-21 days."

In this day and age of Gel and Solid Phase testing, I find it hard to believe that antibodies are being detected ONLY in the eluate beyond the one month mark at a rate that would justifiy the cost of having a policy that has you performing them out to three months.  Even using the one month mark is pretty generous in my opinion.

We perform eluates if the patient has been transfused within the last 14 days, or is suspected of experiencing a transfusion reaction.  We also perform eluates in suspected HDFN cases and in other scenarios where we deem it may be beneficial.  That could include a patient who had been transfused say....two months prior, but only if the clinical situation warranted it; doing it "routinely" would not be considered.

Just as there is no single best test method for identifying antibodies, I'm sure our practice is not fool proof.  But I also believe that finding that rare situation where an antibody can only be detected in the eluate and not in the serum 2.5 months post transfusion does not justify the cost the other 99.4% of the time that these eluates provide information that was already obtained by testing the patient's serum/plasma.

If someone has some stats to suggest otherwise, like I said earlier, I'd love to see them.

I totally agree with you StevenB - nevertheless, at the moment, we still perform the elution up to three months (despite the huge cost/benefit disparity).

@StevenB I'll message you some details of our own internal study regarding 'informative eluates.'

True enough - all great points.  But, alas, we still do them every 3 months.  Something to put on the "TO DO" list...

Based on John Judd's study, we changed our criteria to "transfused within 4 weeks" and based in his work we are still being overly conservative.

We changed ours to transfused within 3 WEEKS on the recommendation of our Immunohematology Reference Laboratory following the Technical Manual reference. However, in the case of a new ID'D Warm Autoimmune patient who is going to likely be a frequent flier we will do an elution prior to transfusion just to get a baseline to compare to if necessary after the patient is transfused.