Question: Can you tell me about the new modifier PT? Can we use it when providing anesthesia for colorectal cancer screenings? West Virginia Subscriber Answer: Modifier PT (CRC screening test converted to diagnostic test or other procedure) was created effective January 1, 2011. Providers should append modifier PT to the diagnostic procedure code being reported when the screening colonoscopy or flexible sigmoidoscopy becomes a diagnostic service, except when reporting anesthesia services. Caution: