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MODIFIER PT VS MODIFIER 33 Screening Colonoscopy

Ann Johnson

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DOES ANYONE HAVE A GOOD ARTICLE DESCRIBING THE DIFFERENCE BETWEEN MODIFIER PT - screening colonoscopy for Medicare pt switched to diagnostic aka therapeutic colonoscopy where pathology is taken VERSUS MODIFIER 33 preventative service for commercial carrier.

I thought that PT was to be used for Medicare pts and that modifier 33 was to be used for commercial carriers to identify that a screening colonoscopy had been changed to a diagnostic therapeutic colonoscopy with pathology taken.

Would love to hear your thoughts on this issue.

ASC Coder
Last edited:


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I don't have an article handy for the -33 but there's a "MLN Matters" addressing the -PT. It's MLN Matters Number MM7012. You can look them up at www.cms.gov.

Some of our commercial payors don't accept the -33. Every policy is different. Now we're also seeing commercial policies with higher coinsurance %'s for PREVENTIVE services versus diagnostic/therapeutic ... how irrational. After getting used to patients calling and complaining that their colonoscopy wasn't 'coded correctly' because it wasn't coded as a screening (because it wasn't - they had symptoms) - now I have patients calling and complaining that I DID code it as a screening (because it was - there were no symptoms) and they have to pay more because it wasn't a diagnostic/therapeutic procedure.