Pathology/Lab Coding Alert

CMS has disabled the unit-of-service edit in the Outpatient Code Editor (OCE) until implementation of the new version in October 2002.

Edit 15, "service unit out of range for procedure," was causing many denials for claims filed under the Outpatient Prospective Payment System (OPPS). CMS discontinued the edit on May 6, 2002, and providers who have had claims returned due to the edit should resubmit after that date.

"Because the maximum units for each service have not been publicized, coders have had to take a hit-or-miss approach to edit 15, which limits the number of times per day a specific HCPCS Codes can be reported for an individual patient," says Laurie Castillo, MA, CPC, CPC-H, CCS-P, member of the national advisory board of the American Academy of Professional Coders (AAPC) and president of Physician Coding and Compliance Consulting in Manassas, Va. "Although coders have a brief reprieve while the edit is suspended, they must understand appropriate modifier usage to ensure fair payment for multiple units of service once the edit is back online."

OCE Edits OPPS Claims

OCE is the CMS software package for processing outpatient claims issued to fiscal intermediaries and carriers. "Although OCE has been used for years to identify incorrect billing data for hospital outpatients, it was expanded to play a central role in processing OPPS claims," Castillo says.

FIs and carriers use the revised code-editing software to edit outpatient Part A and Part B claims. The software has two main functions: 1) to edit claims data to identify and return a message regarding errors, and 2) to assign an ambulatory payment classification (APC) number for each service covered under OPPS to determine reimbursement. Edit 15 for maximum unit of service is just one of 54 edits in OCE. When one of the edits identifies a reporting discrepancy in the diagnosis, procedure, modifier, date, or units of service, for example, the OCE either 1) rejects or denies the claim or line item, or 2) returns or suspends the claim.

"Claims with a service unit greater than allowable for the procedure are returned to the provider [RTP]," says Castillo. A claim RTP means the provider can resubmit the claim once the problems are corrected, according to CMS. "In other words, you can resubmit the bill using appropriate modifiers to override the edit," Castillo says.

CMS Determines Maximum Units of Service

According to program memorandum A-02-025, CMS reviewed narrative code descriptions and standards of medical/surgical practice (those used in the development of the national Correct Coding Initiative) to establish the maximum units of service for each HCPCS code. No maximum allowable units of service have been established for "unlisted procedures," because these codes may represent multiple, different procedures. Nor has CMS established a maximum unit of service for most codes that include "each" or "each additional" as part of the descriptor due to the variable medical conditions involved in their use.

"Until the maximum units of service for each procedure are publicized, coders must rely on the OCE message to determine if the lab has exceeded a limit," Castillo says.

Use Modifiers to Override Edit

"Coders for hospital outpatient pathology and laboratory services need to use modifiers appropriately to ensure payment for multiple units of service that exceed the edit 15 maximums," says Kenneth Wolfgang, MT (ASCP), CPC, CPC-H, member of the national advisory board of the American Academy of Professional Coders and director of coding and analysis for National Health Systems Inc., a coding consultation company in Camp Hill, Pa. Labs must also document the repeated tests or procedures and maintain physician verification of medical necessity for the services.

To override the maximum unit edits for repeated pathology services that might represent a different site or organ system, separate excisions or lesions, or different patient encounters, coders should use modifier -59 (Distinct procedural service),Wolfgang says. "An obvious example is a pathologist's evaluation of multiple skin lesions from different anatomic sites [88305, Level IV surgical pathology, gross and microscopic examination, skin, other than cyst/tag/debridement/plastic repair]," he says.

"But CMS also indicates that modifier -59 is appropriate for reporting multiple clinical lab tests when they involve different anatomic sites, such as bacterial cultures taken from multiple lesion sites (e.g., 87070 and 87075)," Wolfgang says. Report the first procedure without modifier -59 and each subsequent procedure of the same code with modifier -59.

"When performing multiple units of clinical laboratory tests, use modifier -91 (Repeat clinical diagnostic laboratory test) rather than -59 in most cases," says Wolfgang. Use modifier -91 only when it is medically necessary to repeat a lab test for the same patient on the same day in the course of treatment.

For example, if the treating physician orders multiple units of blood glucose (82947, Glucose; quantitative) throughout the day to monitor a patient's blood sugar level, report each unit of 82947 after the first with modifier -91.

"Do not use -91 if tests are run again to confirm initial results or to resolve equipment errors or for other reasons when a normal, one-time reportable result is all that is needed for appropriate patient treatment," Wolfgang says. Also use modifier -91 when the same code is used to report different lab tests. "Many clinical laboratory codes, such as 83520 [Immunoassay, analyte, quantitative; not otherwise specified], describe a procedure that might be used multiple times to examine different analytes," Wolfgang explains.

"Not only is modifier -91 use in these cases a correct coding standard to avoid the appearance of duplicate billing, it is also the correct way to override OCE's edit 15," says Wolfgang. According to CMS, modifier -91 will bypass the unit-of-service edits applied to clinical laboratory test codes in the 80000-89399 range of CPT codes.

"Because modifiers -91 and -59 are interpreted and applied in different ways by different payers and government contractors, ask those sources for specific guidance," Wolfgang says.