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PPP Validation

From Heather DeVries: Greetings! We were inspected by CAP this week, and at one facility they questioned the validation of PPP. Our current procedure, written in 2001, states that the AVERAGE of 10 specimens

must yield a platelet count of less than 5000/uL in order to validate a centrifuge. At the facility in question, one specimen had a count of 10,000/uL, and another was 13,000/uL. But the rest were so low that the average was <5000/uL and the centrifuge was considered validated. The inspector said specimens processed by that centrifuge must be double-spun.
I am wondering what procedures other laboratories use. Do they have a policy for an outlier? Or is one specimen that yields a platelet count of >10,000 enough to say that a centrifuge is not validated for single-spins?

Hi, Heather, thanks for the question, it is sure to generate reponses. I will check with our UAB folks on Wednesday, however just superficially it seems like your CAP inspector was correct. I think each centrifuge mus consistently produce PPP with a count less than 10,000/uL. It would be interesting to learn what the unspun counts wer for the specimens you ran through your QC.

Comments (2)
Specimen Management
Mar 22, 2017 10:35am

I rethought my previous
I rethought my previous comment – we shouldn’t restrict our QC to specimens with counts within the reference range. Although it would be good information, that doesn’t do anything for the patient with a high count that could come through our normal workflow. Either the centrifuge can account for high counts, or it can’t. Do you agree?
Hi, Heather, yes, I agree. There are likely to be many patient specimens with high platelet counts coming through each day, your facility’s centrifugation procedure should be effective in all but the most elevated cases.

Mar 22, 2017 10:22am

Excellent point on the unspun
Excellent point on the unspun counts – I think Kim Kinney had the same thought! If we consider pre-centrifugation counts, would you say that the count should be within our reference range to be acceptable? Any samples with counts outside the range would not be used in validating the PPP.

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