Colon Cancer Screening ICD-10-CM codes

Z12.11 (encounter for screening for malignant neoplasm of colon) is the first-listed diagnosis for an average-risk screening colonoscopy, a screening stool DNA test (81528), and a screening FIT or guaiac test (82270). Z12.12 covers rectal screening and Z12.10 the intestinal tract when the site is not specified. A screening code is only correct when the patient has no symptoms; if the colonoscopy is ordered for rectal bleeding (K62.5) or a change in bowel habit, that is a diagnostic study and the symptom is the reason for the test.

When a polyp is found and removed during a screening colonoscopy, Z12.11 stays first-listed and the polyp is added as a secondary diagnosis (K63.5 for a colon polyp, D12.x for a confirmed adenoma once pathology returns). On the CPT side the procedure changes to the polypectomy code (45385) with modifier PT for Medicare or 33 for commercial payers so that the patient keeps preventive cost sharing. Dropping Z12.11 from the first position because a polyp was found is the single most common coding error on these claims and is what triggers unexpected patient bills.

Surveillance in a high-risk patient is not the same as screening. A colonoscopy performed because of a personal history of adenomatous polyps is coded Z86.0101 (the FY2025 split of the old Z86.010 into Z86.0100 through Z86.0109 by polyp type), and a family history of colon polyps uses the new Z83.71x codes (Z83.710 for adenomatous and serrated polyps). Medicare pays the high-risk screening code G0105 with these history codes every 24 months. For a patient with a personal history of colon cancer who has completed treatment, the surveillance colonoscopy is Z08 first with Z85.038 second; commercial payers often prefer Z09 with the polyp history code for polyp surveillance, so check the plan's colonoscopy policy.

Family history of colon cancer is Z80.0 (family history of malignant neoplasm of digestive organs) and supports the earlier and more frequent screening interval. Never report Z12.11 together with C18.x for an active colon cancer; the malignancy code replaces the screening code.