Pathology/Lab Coding Alert

Tip: Reserve 88384-88386 for ‘gene chips’

Simply counting probes won’t necessarily help you pick the right codes when your lab analyzes multiple nucleic acid markers.

You’ll need to know if the lab is using standard molecular diagnostics techniques or if it’s using a new array technology to characterize disease.

CPT Codes 2006 introduces three new codes for molecular probe arrays. If your lab uses one of the array platforms, you’ll need to learn how to use the following new codes:

• 88384--Array-based evaluation of multiple molecular probes; 11 through 50 probes
• 88385--… 51 through 250 probes
• 88386--… 251 through 500 probes.

What Is an Array, Anyway?

Arrays, commonly called “gene chips,” are devices that can hold many genetic probes in specific positions on a solid surface. “Array technology involves nucleic acid probes or DNA sequences imbedded in a platform such as a slide, chip or microbeads,” says Diana Voorhees, MA, CLS, MT(ASCP)SH, CLCP, principal with DV and Associates Inc. in Salt Lake City. “Microarrays” might pack thousands of probes on a tiny chip, but an array can also be tens of probes fixed on a slide.

By classifying large numbers of genes that may have altered expression patterns, arrays can aid in predicting biological behavior of certain cancers, for instance, and indicating susceptibility to treatment regimes.

Method, Not Number, Determines Code Family

Labs have used molecular diagnostic tests for years to analyze specific genetic or protein markers that aid in characterizing disease. A new CPT text note preceding 83890 specifies that “Codes 83890-83914 are intended for use with molecular diagnostic techniques for analysis of nucleic acids.”

Although arrays provide similar analysis, they allow for a much larger number of probes, and they are generally commercial products that a lab purchases and uses to analyze a given specimen. Another new CPT text note preceding 83890 states, “For array technology using more than 10 probes, see 88384-88386.”

If the lab uses standard molecular diagnostics techniques, you should report each step of the procedure using molecular diagnostics codes 83890-83914. For instance, you would list each probe using 83896 (Molecular diagnostics; nucleic acid probe, each). If the lab analyzes 44 specific nucleic acid probes, you should report 83896 x 44, plus 83912 (Molecular diagnostics; interpretation and report) for the interpretation.

Don’t miss: If the 44 probes are part of an array device that the lab purchases and uses, you should report 88384 for the test. You should document your code selection by stating that the lab used an array-based evaluation. Although arrays often involve large numbers of probes, the method, not the number of probes, is the key to code selection, Voorhees says.

Exception: You cannot report an array code for fewer than 11 probes, regardless of the method. A CPT text note following 88386 says, “For preparation and analyses of less than 11 probes, see 83890-83914.”

Count Probes for Arrays

Once you’ve determined that the lab used an array devise to evaluate multiple molecular probes, you have to know the number of probes to select the proper code. “The manufacturer’s literature should specify the number of probes, and you can use this information to select 88384, 88385 or 88386,” Voorhees says.

Warning: You should only select one code for an array, based on the total number of probes. Don’t use the codes additively, such as 88384 for the first 50 probes and 88385 for the next 250 probes.

Report Preparation in Addition to Array Codes

If the lab prepares the specimen for an array analysis using molecular diagnostic procedures such as nucleic acid extraction, enzymatic digestion or gene amplification, you can separately report the preparation steps along with the proper array code. A CPT text note following 88386 says, “For preparation of array-based evaluation, see 83890-83892, 83898-83901.”

For example: Laboratory-developed tests for cystic fibrosis screening use Third Wave Technologies’ CFTR InPlex ASRs for 46 mutations. Whether the lab reports the nucleic acid probe analysis using molecular diagnostics codes (such as 83896, Molecular diagnostics; nucleic acid probe, each) or the new array codes, you can separately report the specimen preparation and gene amplification as follows:

• 83891--Molecular diagnostics; isolation or extraction of highly purified nucleic acid

For the 19-plex amplification:

• 83900--Molecular diagnostics; amplification of patient nucleic acid, multiplex, first two nucleic acid sequences

• +83901 x 17--Molecular diagnostics; amplification of patient nucleic acid, multiplex, each additional nucleic acid sequence (list separately in addition to code for primary procedure)

For two cleavages per mutation (46 mutations):

• 83892 x 92--Molecular diagnostics; enzymatic digestion.

The bottom line: Although the preparation charges are the same, the new array codes may pay much less than the molecular diagnostics codes for the same probes. Laboratory-developed tests using the CFTR InPlex ASRs use 5 probes for each of the 46 mutations (83896 x 5 x 46), as well as signal amplification (83908 x 46) and mutational scanning (83903 x 46) for each nucleic acid sequence, says Stephen Day, PhD, former director of medical affairs for Third Wave Technologies in Madison Wis. “Reimbursement for array code 88385 is far less than for all of the combined molecular diagnostics codes for this service,” he says. 

Array Codes Include Interpretation and Report

Although you can list molecular diagnostics specimen-preparation codes with array codes, you can’t use molecular diagnostics interpretation code 83912. “The array codes include the evaluation and reporting services, so you should not list 83912 with 88384-88386,” Voorhees says.

Unlike the molecular diagnostics codes, the array codes include a technical component for actually performing the test and a professional component for the pathologist’s professional interpretation. The Medicare Physician Fee Schedule lists a modifier TC (Technical component) and modifier 26 (Professional component) value for these codes. 

Watch for Lab Certification Specialty

CPT added the array codes to the anatomic pathology subsection because pathologists will use the tests primarily to process surgical and cytopathology specimens, according to the AMA’s CPT Changes 2006, An Insider’s View. That means labs that use the new codes should have a histopathology certification under the Clinical Laboratory Improvement Amendments (CLIA).

If your lab performs molecular diagnostics but is not registered for histopathology, you may have problems with payment. “But most high-complexity labs that perform molecular diagnostics should not have a problem with certification for the new array codes,” Voorhees says.