MicroCoomb’s test or Incubated (sensitive) DAT

[JoyG]

Hi everyone,

I have been requested to perform the above on a patient with clinical signs of hemolysis but DAT negative.  I am having trouble finding a reference.  How is the above performed?

[galvania]

Dear Joy

Most DATs are pretty sensitive now anyway.  I have never heard that 'incubating' a DAT will help it.  I would suggest that you use a polyspecific Coombs reagent - gel is more sensitive than tube - in case it's IgA (rare, but possible).  - Or a battery of monospecific AHGs. I would also check with the clinician to see if he's possibly thinking about PCH - this could give you a negative DAT as all the coated cells would already be haemolysed - but then you need to do a Ham's test, with added fresh AB plasma for a source of complement.

[Malcolm Needs ☆]

I agree wholeheartedly with Anna, but would add that it could be hyperhaemolysis - very rare, but it happens, and you do get a negative DAT.

 

WAIHA can also present with a negative DAT, but again, this is rare.

[JoyG]

Thank you!

[carolyn swickard]

^{Isn't this the same as that Super DAT that has been discussd before?  I couldn't find the thread before when I searched under "Super DAT", does anyone else know how to find it?}

[David Saikin]

You could always try an elution . . . I have seen neg DATs with a strongly positive eluate in gel. (using the Immucor ELU II kit).

[AMcCord]

In the past we had an oncologist who wanted 'super sensitive' DATs on a few of his patients. We sent them to our ARC reference lab, who sent them on the the ARC in Philadelphia. How they did the test, I don't know. Haven't had another request since that Dr left.