ICD-10 Code K57.21 – Diverticulitis of large intestine with perforation and abscess with bleeding (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K57.21 – Diverticulitis of large intestine with perforation and abscess with bleeding
What it is
K57.21 identifies diverticulitis in the large intestine when the inflamed diverticula have perforated, formed an abscess, and are associated with bleeding. Use it for documented complicated diverticular disease of the colon.
Clinical signs
Typical findings include left lower quadrant abdominal pain, fever, localized tenderness, and evidence of perforation or abscess on imaging or operative report. Bleeding must also be documented; clinical features vary, so refer to documentation.
When to use this code
Use this code when the record clearly states diverticulitis of the large intestine with perforation and abscess, and bleeding is present. It may appear in emergency, inpatient, or surgical documentation. You should code from the provider’s final diagnosis and supporting imaging or procedure notes.
Do not use for
Do not use K57.21 for uncomplicated diverticulitis, diverticulosis without inflammation, or diverticulitis without documented bleeding. Check documentation if perforation, abscess, or the bleeding site is unclear.
Coding tip
Look for all three elements—perforation, abscess, and bleeding—before assigning K57.21.