YorkshireExile

You are lucky you have retired! Definition is (I think!) - a parameter associated with the result of a measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand. The ISO requirement we are supposed to meet is: 5.5.1.4 Where examinations include a measurement step but do not report a measured quantity value, the laboratory should calculate the uncertainty of the measurement step where it has utility in assessing the reliability of the examination procedure or has influence on the reported result. The explanation is this: To ensure that measurement results are useful and safe in medical practice and to permit meaningful comparison with medical decision limits and previous results of the same kind in the same individual, medical laboratories require estimates for the overall variability in values reported by their measurement procedures." I imagine that all makes you none the wiser!! Sorry - I couldn`t do it in 50 words!

This question may be mainly for UK Blood Transfusion labs, but we have just had an ISO 15189 inspection and our inspector says we should be doing Uncertainty of Measurement (UoM) in Blood Transfusion labs, especially with regards to Blood grouping. Now, I have no idea how UoM relates to Blood Bank procedures, and my inspector failed to convince me, but he said that this is quite common in the UK now and many Transfusion labs are doing this. So for anyone working in a UK Blood Bank who are ISO 15189 accredited, are you doing UoM calculations for any BB procedure? If you are, can you please explain to me how it is relevant and what are you actually doing? UoM is relevant to Haematology and Chemistry with all their CVs and SDs and Bias calculations etc, but what the heck has it got to do with Blood Bank work!

We were told by our CAP inspectors that we need to include evidence on our competency form that all the tasks were actually done. We had to include MRNs, or Accession numbers, or product unit numbers. I can`t see any space on you form to include these details. Do you add them, or do you just fill in the date/method boxes?

Thank you "Byfaith". it does help! Have you ever had any problems performing EXM with Cerner Millenium? Or is it all good as long as the EXM rules are built correctly?

We recently got some new refrigerators and for the alarm checks there is just a button we press for high and low alarm checks which automatically cools or warms the temperature of the probe. This only affects the probe - the chart pen does not move. i would presume all modern refrigerators have this function. Why should I have to mess around with the probe, taking it out of its container and placing it in warm or cold water - possibly damaging it in the process - all so that the pen on the chart can move? Aren``t these automatic probe checks, with retreiveable documentation, good enough for CAP?

Thank you for the replies. What about another couple of scenarios we are considering. If an automated blood group is ever edited for any reason, does that disqualify from doing the EXM? If for some reason a RBC unit is not entered electronically into your inventory in the computer using the barcodes, but is instead entered manually, does that disqualify from doing the EXM?

We are currently validating the use of electronic crossmatch in our hospital. For those hospitals who currently do EXM, if the DAT is positive does that mean that sample is not valid for EXM? If so, how did you validate this? We are having difficulty to make a positive DAT part of the criteria for EXM exclusion. All we can think of is to add Positive DAT to the list of antibodies under antibody ID so it would then be recognised. The computer system we are using is Cerner Millenium.

Could you send me a copy as well? We recently re-designed our competency assessment to meet the six elements that CAP says you have to include, and it seems so cumbersome and lengthy now. Thank you.

Smiller - When you say you have done a "recent" pos DAT workup, how do you define recent? What time frame?

And if not pregnant or not transfused within the last 3 months?

What do people use as the criteria for when to repeat antibody investigations? If the previous sample was only three days old, and the new antibody screen was positive with the same strength reactions as the three day old one, would you do a full antibody workup again? What if the previous sample was seven days old or even one month old? When would you repeat the full antibody workup? if the patient has been recently transfused or is pregnant would that affect when you repeat your antibody work up? Interested to hear what you all do.....

For our hospital the donation center does not provide whole blood so we have to reconstitute PRBC with plasma to make an exchange unit. I would like to ask Malcolm what type of red cells are used for exchange transfusions in the UK? Is it CPD-SAGM or just CPD units? We get CPD-SAGM units from our supplier and have to centrifuge the unit to remove the SAGM, then we add plasma to achieve a HCT of around 45 to 50%.

Does anyone use RBC expiration rate for their monthly quality indicators (key performance indicators)? If so, what do you use as your denominator? Do you use number of RBCs transfused in the month or the the number of RBCs received from your blood supplier per month? We use number of RBCs received from our blood supplier as we wanted to monitor we don`t excessively order blood that may not be used and expire. But now I have read that this may not be correct. Also, what is your target? We state our expiration rate should be <2%.

Thank you Baby Banker and Neil for your recent input. So as we are using leucoreduced blood, does that mean that a blood unit would never be implicated in causing CMV infection in a recipient? Or there is. and always will be, a very small risk a leucoreduced unit can cause a CMV infection?

Thanks Malcolm, So you are saying that blood should be leucoreduced and CMV negative for the categories that I stated? What if the blood donation center that supplies my blood does not do CMV testing? All I can do then is give the leucoreduced blood. On a similar topic, we had a newborn baby receiving a number of leucodepleted RBC top-up transfusions since birth. At 35 days old the baby had a CMV quantitative screen done and was CMV negative. At 65 days old the baby was tested again and the CMV screen was positive. Is the reason for this purely down to one of the transfused units? Or could other factors be involved eg infection passed on by another healthcare worker, or by the family, or by environmental causes?