Pathology/Lab Coding Alert

Under Medicares revised outpatient code editor (OCE), coders for hospital outpatient pathology and laboratory services will need to use modifiers appropriately to ensure reimbursement for multiple units of service. The national maximum units of service edits are part of the revision to OCE, which limits the number of times per day a specific CPT code can be reported for an individual patient. Although the revised OCE went into effect August 1, 2000, the maximum unit edits have been delayed until the January 2001 OCE update, according to a HCFA memo.

The maximum unit edits have not yet been made public (as of press time), so it is difficult to estimate the impact the edits might have on your practice or laboratory. You can prepare by learning appropriate coding strategies to override the edits for cases that warrant exceeding the maximum units of service. Under the maximum unit edits, billers must learn how to manage coding in order to be reimbursed for all services provided to hospital outpatients, advises 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 its northern Virginia chapter.

When a pathologist or laboratory legitimately provides multiple units of service beyond the maximum established by the OCE, appropriate modifiers must be used to override the maximum unit edits. When reporting multiple units of service, the pathologist must document the repeated tests and support the medical necessity of the procedures.

Use Modifier -59 for Repeat Anatomic Services

To override the maximum unit edits for repeat anatomic pathology services, coders can use modifier -59 (distinct procedural service), Castillo says. HCFA program memorandum A-00-35 indicates that if this modifier is present on a line item of an outpatient claim, the unit edits are not applied. Modifier -59 can be used to indicate that special circumstances warrant reporting the given number of units of a procedure, even if it is more than the maximum determined by HCFA. The multiple units might represent a different site or organ system, separate incision/excision, separate lesion or separate injury, as described in the CPT 2001 direction for modifier -59.

For example, if the maximum units for CPT 88305 (level IV surgical pathology, gross and microscopic examination) are established at 10 (as proposed by HCFA), but it is medically necessary for the pathologist to examine 12 separate specimens at that level, use modifier -59. The line items listed for the first 10 units of service should not be reported with the modifier. However, to be reimbursed for the additional two units, list each of them with the -59 modifier.

Modifier -91 for Multiple Units of Lab Tests

When multiple units of a laboratory test are performed, modifier -91 (repeat clinical diagnostic laboratory test) should be used under appropriate circumstances, 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. Modifier -91 may be used only for laboratory tests paid under the clinical diagnostic laboratory fee schedule. It should only be coded when the same test is conducted more than once for the same patient on the same day because multiple results are required in the course of treatment, Wolfgang says.

For example, multiple units of blood glucose (82947, glucose; quantitative) may be ordered at various times throughout the day if the treating physician needs to monitor a patients blood sugar level. Each subsequent measurement should be reported with modifier -91 to indicate that the test was repeated because it was medically necessary for the treatment of the patient.

Modifier -91 may also be required when the same code is used to report different lab tests. Many clinical laboratory codes describe a procedure that might be used to examine different analytes, Wolfgang says. For example, 83520 (immunoassay, analyte, quantitative; not otherwise specified) is commonly used to describe procedures investigating multiple individual substances. If four of the analytes are carried out for the same patient, the first unit would be reported without modifier -91, while each subsequent unit would be reported with the modifier.

Using modifier -91 as indicated in these examples is the appropriate coding standard to avoid the appearance of duplicate billing. It is also the only way to override the OCE maximum-unit edits for clinical laboratory tests. HCFA program memorandum A-00-35 states that if modifier -91 is present on a line item of an outpatient claim, the unit edits are not applied.

Remember that modifier -91 should be used only when it is medically necessary to repeat a laboratory test in the course of patient treatment. Do not use -91 if tests are run again for the following reasons:

To confirm initial results;
Because of testing problems related to specimens or equipment; and
For any other reason when a normal, one-time reportable result is all that is needed for appropriate patient treatment.

Local Rules and National Maximums

Many Medicare carriers local medical review policies (LMRPs) already contain limitations on units of service for various laboratory and pathology procedures. HCFA has not indicated whether it will allow more restrictive local units of service policies to override the national maximum units of service edits in the OCE. If billers find more restrictive local policies, they should ask their provider relations contact to change the policy to align with the national maximums. Be sure to reference any HCFA transmittals and program memorandums to support the change, Castillo advises. You should also contact HCFA and request a clarification of the policy when there is a discrepancy.

Once the OCE maximum units of service edits are in place, billers will need to use modifiers appropriately to ensure reimbursement for all pathology and lab services provided to hospital outpatients. Coders should already be using modifier -91 for repeat laboratory procedures to avoid the appearance of duplicate billing, Wolfgang says. And they should be prepared to use modifier -59 appropriately when the number of anatomic pathology services legitimately exceeds the nationally established maximum.