Body Fluid Controls

[johermajan]

We run body fluids except CSF on LH750. We do background check first and then run sample in duplicate but we never use any external control for QC. We got dinged during our last CAP inspection for not using any control material or not having any procedural control. He cited that running the test in duplicate has nothing to do with QC requirement. What does your laboratory do? Do you use external controls?

[nziegler]

Beckman has specific body fluid controls available.  We run those.

[EWEVANS]

We use a procedural control on all body fluids. We make a cytospin slide on all specimens (regardless of count) and compare that slide to the number of cells counted (either via instrumentation or hemacytometer). We look to see if the count 'matches' what we see on the slide, i.e. if the RBC count was 10,000 and the WBC was 100, we should see 1000 RBC for every WBC (or so). If you look at the slide and you see more WBCs then RBCs, we require the count to be repeated. We notate this internal QC check on each report in our LIS. We've never had any CAP issues regarding this policy.

Edited July 17, 2013 by EWEVANS

[SMILLER]

What? You are using a cytospin to verify a count from an automated analyzer and/or hemocytometer? Am I getting this right? You may as well use a Wright's stained CBC peripheral smear to verify a RBC count!

Scott

[EWEVANS]

Yes, and I understand what you are saying. We don't have a large number of body fluid counts (about 1/day) and we seem to get them in batches, none for a few days, then 3-4 in one day, and not all of them are run through our analyzer (CSF, extremely low cell counts below linearity, so small a specimen volume, etc.) It doesn't seem cost effective to buy a commercial control when it is easy to look at the cytospin (which we would make on the specimen anyway) and confirm that the cell count appears to match. Besides, we very rarely see high enough RBC counts on body fluids that would compare to a peripheral blood cell count. If we do they are a usually clotted, so a cell count cannot be assessed, or b, if they are that high they are run on our Sysmex and the lower control level if adequate.

What we do is a simple, cost effective procedural control that suits our test volume and type of specimen seen. If we saw a higher volume of specimens that had a significant cell counts, I would re-think our control method.

[johermajan]

I agree that it doesn't seem cost effective to buy a commercial control when you're getting low volumes of body fluid request. But I don't understand how the correlation of the  automated or hemocytometer cell count with a cytospin slide works, considering that a cytospin is a concentrated preparation of the body fluid being tested.