ICD-10 Code C19 – Malignant neoplasm of rectosigmoid junction (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C19 – Malignant neoplasm of rectosigmoid junction
What it is
C19 identifies a malignant tumor arising at the rectosigmoid junction, where the rectum meets the sigmoid colon. Use it when documentation specifies this anatomic site and confirms cancer.
Clinical signs
Common findings may include rectal bleeding, change in bowel habits, abdominal pain, or signs of bowel obstruction. Clinical features vary; refer to documentation.
When to use this code
Use C19 when the provider documents primary cancer of the rectosigmoid junction, including pathology, imaging, or operative reports that clearly localize the tumor there. If the record only says colon cancer or rectal cancer without site specificity, check documentation before coding.
Do not use for
Do not use C19 for benign neoplasms, carcinoma in situ, or metastatic disease to the rectosigmoid junction. If the primary site is elsewhere in the colon or rectum, choose the more specific code.
Coding tip
Code the site exactly as documented; when the tumor spans adjacent sites, verify whether the record supports rectosigmoid junction coding.