Pathology/Lab Coding Alert

When a payer assumes that you've either unbundled or duplicate-billed, modifier -59 (Distinct procedural service) and -91 (Repeat clinical diagnostic laboratory test) can tell it otherwise. The problem is knowing when and how to use each modifier for multiple services, repeat tests or bundled procedures.

Instructions for modifiers -91 and -59 and circumstances for their use sometimes appear to overlap "" says Kenneth Wolfgang MT (ASCP) CPC CPC-H director of coding and analysis for National Health Systems Inc. a coding consultation company in Camp Hill Pa. Even knowing when to use a modifier and when to report unmodified multiple units of service is not always clear.

Not every repeat lab test requires modifier -91 and not every distinct service requires modifier -59. ""To sort out which modifier to use you have to know the reason that the two tests were ordered together and your payers' rules for the claim "" Wolfgang explains. Report -91 for Subsequent Test ValuesEven though CPT defines modifier -91 as ""Repeat clinical diagnostic laboratory test "" not every lab test repeated for the same patient on the same day warrants using it. ""Only use -91 when it is medically necessary to obtain subsequent reportable test values "" says Anne Pontius MBA CMPE MT (ASCP) president of Laboratory Compliance Consultants Inc. in Raleigh N.C.

For example a patient with high blood pressure who has been on a low-salt diet may receive a plasma renin activity (PRA) test (84244 Renin) in the morning in the supine position. Because physicians may use variations in PRA levels due to time of day and patient position to evaluate certain conditions such as hyperaldosteronism they may order a repeat renin in the afternoon with the patient standing upright for a period of time. Report the second 84244 with modifier -91 to indicate that the lab performed two separate renin assays for the same patient on the same day.

You should use modifier -91 even if you conduct a lab test as part of a panel and repeat the test separately at another time of day Wolfgang says. ""On rare occasions it may be necessary to assign a -91 modifier even though you're reporting two different codes. It is appropriate to report -91 because you're repeating the same lab test for subsequent results.""

If the lab performs an electrolyte panel to evaluate acidosis for instance and the physician later orders a follow-up bicarbonate test report both 80051 (Electrolyte panel) and 82374 (Carbon dioxide [bicarbonate]). Append modifier -91 to 82374 to specify that you repeated the bicarbonate. Medicare's Correct Coding Initiative (CCI) edits require you to use modifier -91 in this instance to indicate that you did not ""unbundle"" the bicarbonate from [...]