Pathology/Lab Coding Alert

Question: We perform a susceptibility test for staphylococcus isolates using a Vitek analyzer. Because one of the isolates tests Penicillin sensitive while most are Penicillin resistant, we also had to perform an induced beta lactamase test. Can we code the beta lactamase enzyme detection (87185) in addition to the original susceptibility study?

New York Subscriber

Answer: No, for a single isolate, you should not report 87185 in addition to the code for the original susceptibility test. Doing so goes against both CPT coding principles and Correct Coding Initiative (CCI) edits.

CPT provides a family of codes for susceptibility studies as follows, based on the lab method:

• 87181 -- Susceptibility studies, antimicrobial agent; agar dilution method, per agent (e.g., antibiotic gradient strip)

• 87184 -- ... disk method, per plate (12 or fewer agents)

• 87185 -- ... enzyme detection (e.g., beta lactamase), per enzyme

• 87186 -- ... microdilution or agar dilution (minimum inhibitory concentration [MIC] or breakpoint), each multi-antimicrobial, per plate

• 87188 -- ... macrobroth dilution method, each agent

• 87190 -- ... mycobacteria, proportion method, each agent.

CPT guideline: For a family of codes that share a common description preceding the semicolon, you should choose the single code within the family that most closely describes the procedure your lab performs.

CCI principle: Because the codes in the same family provide the same diagnostic information by different methods, the codes are "mutually exclusive."

It would not be medically necessary to perform two tests for the same purpose. That's why CCI bundles each of the susceptibility codes with all the other codes in the family on the mutually exclusive edit table.

Exception: Within the same family, CPT lists an add-on code +87187 (... microdilution or agar dilution, minimum lethal concentration [MLC], eachplate [List separately in addition to code for primary procedure]). Per  CPT instructions, you can list this code in addition to any of the other susceptibility study codes.

The case you describe presents a dilemma, because you could argue for the medical necessity of the beta lactamase test in addition to your original susceptibility test. Some would argue that 87185 should be an add-on code like +87187, but it is not.

Bottom line: You cannot legitimately override the CCI edit for 87185 and your original susceptibility test from the same family if you perform the tests on the same isolate.

-- Reader Questions and You Be the Coder were prepared with the assistance of R.M. Stainton Jr., MD, president of Doctors' Anatomic Pathology Services in Jonesboro, Ark.