New modifier became effective Jan. 1 -- here's how you'll report it. The question of how to code a screening colonoscopy that becomes diagnostic during the course of the procedure -- and whether the patient's deductible applies -- has long puzzled some practices, but a new Medicare modifier solves that problem. Learn how modifier PT (CRC screening test converted to diagnostic test or other procedure) can solve your colonoscopy reimbursement woes. Get to Know Modifier PT Basics Effective Jan. 1, Medicare carriers accept new modifier PT to explain when your physician starts a screening colonoscopy that then becomes a diagnostic procedure. "This tells the MAC contractor that the service started as a screening procedure (e.g. G0105 [Colorectal cancer screening; colonoscopy on individual at high risk], G0121 [Colorectal cancer screening; colonoscopy on individual not meeting criteria for high risk]) but an abnormality was found and the procedure became diagnostic or therapeutic," says Joel V. Brill, MD, AGAF, CHCQM, American Gastroenterological Association, AMA/Specialty Society Relative Value Update Committee (RUC) Advisory Committee Member. When appended to your procedure code, "the modifier will indicate to Medicare to waive the deductible for a diagnostic procedure," says Christine Ross, CPC, with Digestive Healthcare Center in Hillsborough, N.J. Why the change? Avoid Reporting G Code With Modifier PT Once the physician indicates that the screening procedure has turned diagnostic, you'll bill only the diagnostic colonoscopy code, and not the screening code (G0104-G0106, G0120-G0121). Not only is this correct coding, but it's also the only way you can use modifier PT. The MLN Matters article notes that modifier PT should only be appended to a CPT code in the surgical range of 10000 to 69999. Therefore, you should not append modifier PT to a G code, says Brill, who represents the American Gastroenterological Association on the CPT Editorial Panel. For example: Don't Ditch 'V' Codes Because your colonoscopy started out as a screening procedure, your diagnosis code should reflect both the screening nature of the visit and the actual condition that the physician treated. CMS tackled this topic in MLN Matters article SE0706, with the instruction, "CMS advises that, whether or not an abnormality is found, if a service to a Medicare beneficiary starts out as a screening examination (colonoscopy or sigmoidoscopy), then the primary diagnosis should be indicated on the form CMS-1500 (or its electronic equivalent) using the ICD-9 code for the screening examination... Indicate the secondary diagnosis using the ICD-9-CM code for the abnormal finding (polyp, etc.)." You can read this article at www.cms.gov/MLNMattersArticles/downloads/SE0746.pdf. Therefore, in the example described above, the claim would appear with V76.51 (Special screening for malignant neoplasms, colon) as the primary diagnosis. You should then append the appropriate diagnostic modifier to your claim. For example, if the surgeon removes a benign polyp from the colon, you'll report 211.3 (Benign neoplasm of colon), says Cheryl H. Ray, CCS, CPMA, CGCS, with Atlantic Gastroenterology, PA in Greenville, N.C.