Overcentrifugation may cause either a false negative result (if too much agitation is required for...

Overcentrifugation may cause either a false negative result (if too much agitation is required for resuspension), or a false positive, (if centrifuged clumps cannot be completely dispersed). High concentration of IgG paraprotein, and failure to adequately wash cells can leave unbound IgG which will neutralize antiglobulin reagent. Delay of addition of antiglobulin reagent may allow previously bound IgG antibody to dissociate from red cells.

Blood bank

Which of the following might cause a false positive indirect antiglobulin test: