What is the difference between the anachoice screen and the ana screen, ifa? the first one came back positve, but the second came back negative.

Diff. lab techniques: Different labs have different ANA tests, which is a test for antibodies a person makes that attach to his own body's tissues, that end up causing auto-immune disease. Modern tests use "reflex" or "cascade" techniques, meaning one test is done first, and then if positive, another test is done, and then if positive again, a third test is done. Tests have various "positive" ranges (gets complicated).