QC of saline cubes attached to cell washers

[Julie Shannon]

We are using S/P Cat # B3158-1 and there is a statement on the cube saying that a negative control must be run daily at Coombs.

One issue is that we have 12 washers and rarely would each be used in a calendar day. But - since we do not log the station but rather the QC rack, we can't prove that a station is NIU. We work in circular pods with lazy susans so we generally share reagent racks.

Second issue - what is a suitable negative control? I am thinking just a negative DAT should be sufficient? Maybe one drop of a reverse or screen cell?

I am stumped on exactly how to implement this so I figured I would ask the subject matter experts.

[Malcolm Needs ☆]

Think you just need to run a sample that has inert plasma and red cells, and then, once washed, add your AHG, spin gently (should be negative) and then add IgG-coated red cells, mix, spin gently again, and should be positive.

It's just to ensure that the wash is efficient. Sadly, to do it properly, you should do it for each bay in each of your washers!

[Julie Shannon]

The requirement doesn't indicate that it is checking adequate washing (that would be cell washer QC). This seems to be something stated on the box by the manufacturer - seems like it is to be sure the saline isn't giving false positives (contamination).

[Malcolm Needs ☆]

Ah, I see what you mean Julie, but this test would surely do to show that the saline would not produce false positives. The only thing is that you would only need to do a couple of tubes, rather than 1 in each bay as I originally suggested.

[John C. Staley]

Or.........buy some one else's saline. Just a thought.

[SMILLER]

We run a weak D negative control daily, ending with a tube coombs, so i would think we would be covered. Except I am pretty sure that we do not record our lot numbers of saline anyway. Probably should go read what it says on our saline cubes. Never been an issue with inspectors as far as I know.

[ANORRIS]

The cube of saline only suggests a neg control be run daily..."should" what does aabb say?

[AMcCord]

My saline simply says 'inspect visually on a daily basis' for discoloration and particulates. I have a box for a checkmark for daily visual inspection of the saline along with all other reagents in our rack. We also perform a negative AHG test post incubation/wash, so I think that would cover false positives due to bacterial contamination, if an inspector asked.

[David Saikin]

Why not just verify "negativity" with your first patient run of the day . . . assuming the pt will have a negative absc (or whatever). It seems this is like proving my balance for donors is working correctly. I weigh the 1st unit collected each day. It has to fall into defined parameters - if it does, then my balance is working fine. Why make extra work when you are already in compliance - JUST DEFINE IT!

[David Saikin]

Should - you can do it if you want to. Must - you must do it. That's how the FDA interps those words.

[AMcCord]

I agree with David - spell it out so that something you are already doing anyway will take care of the requirement.

[Julie Shannon]

That is exactly what we are investigating as of today. Just asked for a sample cube from a different source. What a pain! We surely would know right away if we had a contaminated cube on board.