Weak positive indicator control cells when no stir ball is present

[kelliott15506]

Has anyone seen a weak positive reaction for the indicator control cells when no stir ball is present in the vial of indicator cells?

[AMcCord]

Yes. Without the stir ball the Echo is sampling a reduced number of indicator red cells/more diluent. The longer the vial is on the instrument without the stir ball, the more settled the red cells become and fewer and fewer of them are sampled/added to the test well. In the package insert for the indicator cells under Limitations: "Addition of too few indicator cells, as might occur with improper mixing of the reagent or through hemolysis of red cells, will cause weak falsely positive results." The vial should be discarded and a new vial with a stir ball loaded on the instrument before performing any additional testing. You'll see funky results with A and B cells missing the stir ball, too. Those vials should also be discarded and replaced with new vials/stir ball added.

[MeganPLT]

Great answer @AMcCord! I would just add - if you are just getting used to the echo or NEO - everyone has forgotten once and then they are really careful not to do it again; so don't beat yourselves up! I know I still check by ringing the vial like a bell at the beginning of my shift just to make sure! - Because - if the vial doesn't have the stirball and the person before you loaded it; it is stills works for the first couple hours or so until the red cells start to settle to the bottom of the vial!