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Daily QC for DAT and weak D test?

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I am wondering if daily QC is needed for DAT and weak D test if we perform the test as following?

DAT:

Poly-specific - patient's tube plus saline control tube;

Mono-specific: patient IgG / IgG pos. control / IgG neg. control

                        patient C3d / C3d pos. control / C3d neg. control.

Weak D test:

patient anti-D tube plus Rh control tube.

 

In the facility I previously worked for, we did as the above and did not do daily QC; but where I currently work, we do daily QC, as well as the above. Is it necessary to do both? Need you input and if you can provide references regarding the issues, it will be much appreciated. Thanks. 

 

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I'm not sure I really understand what you are getting at in your last post.  Unless I am mistaken, which I may well be, there seems to be a mix-up between 'reagent control', (in the sense of, making sure that the patient is not reacting non-specifically with the reagent) and QC (where you check that the reagent is working correctly).

In terms of checking to see that your patient is not reacting non-specifically with a component of the buffer or diluent, this really needs to be carried out with every single test.  If you are working in cards or cassettes, then most cards/cassettes have an in-build control that fulfils this purpose in cases where you are using patient red cells.  If you are working in tube, you need to make sure that whatever you take as a control contains as nearly as possible whatever substances are contained in the antiserum.  It is very important in the case of a weak D test, as if the patient has a positive DAT this will automatically give you a (false) positive in the weak D test)

For QC, as to whether you carry out a daily control and how you do that depends rather on your national guidelines.

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The guideline says "Test polyspecific and anti-IgG reagents against IgG coated cells, C3 coated cells and unsensitised cells at time of use or once daily as applicable".

Although to me the guideline is not very clear, my interpretation to it is that for polyspecific reagent, we can test it daily against IgG coated cells (supposed to be positive), C3 coated cells (supposed to be positive as well)  and unsensitised cells (such like commercial antibody screening cells - supposed to be negative) as daily QC. For the mono-specific anti-IgG and anti-C3d reagents, since we do pos. control and neg. control along with patient samples at the time of use, we do not need to do daily QC for them. Does anyone agree with my interpretation regarding this issue? Could you please share the policy regarding this issue in your facility? Thank you.

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We don't perform QC with the patient test, we do it once daily. We do include a saline control with DATs and a 6% albumin control with weak D testing.

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We QC the anti-C3b, -C3d on every day of use as required by standards (this is not a reagent we use every day). As David says, a positive and negative control are done for QC. We use a drop of Coombs Control cells for the negative control and a drop of Complement Control cells for the positive control. With the patient we run a saline control. For Weak D testing we run the Monoclonal Control as recommended by the manufacturer of the antisera.

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