Could a small recurring coding error be costing your lab more than you think? Volume multiplies every mistake, since a single coding pattern repeats across hundreds or thousands of tests before anyone notices. Medical necessity mismatches, where the diagnosis doesn’t clearly support the test ordered, are among the most common causes of denials, especially for panels and reflex testing. Laboratory medical billing services catch mismatched diagnosis codes and unusual test frequency early, verify necessity before submission, and work denials quickly.