ICD-10 Code C20 – Malignant neoplasm of rectum (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C20 – Malignant neoplasm of rectum
What it is
C20 identifies a malignant tumor arising in the rectum. Use it when the record documents rectal cancer or a primary rectal malignancy.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include rectal bleeding, altered bowel habits, tenesmus, or a rectal mass confirmed by examination or imaging.
When to use this code
Use C20 when the provider documents a primary malignant neoplasm of the rectum, including an established diagnosis or biopsy-confirmed rectal cancer. You may also use it when the note clearly identifies rectal origin, even if staging details are pending.
Do not use for
Do not use C20 for benign rectal lesions, anal canal cancer, or malignancies documented only as colon or colorectal without rectal site confirmation. Check documentation if the anatomic site is unclear.
Coding tip
Always verify the exact tumor site in the pathology, endoscopy, or oncology note before assigning C20.