Clinical Laboratory Procedures: Duplicate Denials

Published 07/07/2020

Denial Reason, Reason/Remark Code(s)
  • OA-18 - Duplicate Service(s): Same service submitted for the same patient
  • CPT codes: 36415, 80048, 80053, 80061, 83036, 84443, 85610

First: Verify the status of your claim before resubmitting. Use the Palmetto GBA eServices tool or call the Palmetto GBA Interactive Voice Response (IVR) unit.

  • All providers that have an EDI Enrollment Agreement on file may register to use this tool. If you haven’t already registered, please consider doing so.
  • Access the introductory article to learn more by selecting the 'Introducing eServices' graphic on the top of any of our main contract Web pages
  • Please note: Only one provider administrator per EDI Enrollment Agreement/per PTAN/NPI combination performs the registration process. The provider administrator can then grant permission to additional users related to that PTAN/NPI.
  • Billing services and clearinghouses should contact their provider clients to gain access to the system
  • Specific instructions for accessing claim status information through eServices are available in the eServices User Manual (PDF, 8.33 MB)

CPT modifier 91 may be submitted to identify an identical laboratory test for the same patient on the same date.

  • This modifier may not be submitted when tests are rerun to confirm initial results due to testing problems with specimens or equipment, or for any other reason when a normal, one-time, reportable result is all that is required
  • This modifier may not be used when other codes describe a series of test results (e.g., glucose tolerance tests)
  • For clinical laboratory tests ordered by an ESRD facility: these tests must be submitted with CPT modifier 91 if any single service (same CPT code) is ordered for the same patient, and the specimen is collected more than once in a single day, and the service is medically necessary
    • CPT modifier 91 must be submitted with services that meet these criteria, regardless of whether the test is also submitted with HCPCS modifiers CD, CE or EF
    • Any line item on a claim that meets these criteria and is submitted with CPT modifier 91 will be included into the calculation of the 50/50 rule
    • After calculation of the 50/50 rule, services used to determine the payment amount may not exceed 22


  • Read more about the 50/50 rule and instructions for submitting CPT modifier 91 in these circumstances in the CMS MLN Matters article MM4101

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