Ulcerative (chronic) rectosigmoiditis with fistula

This code signifies chronic inflammation of the rectum and sigmoid colon, characteristic of ulcerative colitis, complicated by the presence of a fistula. A fistula is an abnormal connection between two epithelialized surfaces, in this case, originating from the affected rectosigmoid area. This condition is a severe manifestation of ulcerative colitis, indicating significant transmural inflammation.

Use this code when documentation clearly indicates a diagnosis of ulcerative colitis affecting both the rectum and sigmoid colon, and a fistula is present as a complication. This typically applies to patients experiencing persistent symptoms such as bloody diarrhea, abdominal pain, and tenesmus, with endoscopic and/or imaging evidence confirming rectosigmoid inflammation and fistula formation. Supporting documentation includes colonoscopy reports, pathology findings, and imaging studies (e.g., MRI, CT scan) detailing the fistula.

• Ensure the documentation specifies "ulcerative" rectosigmoiditis to differentiate from other forms of colitis.
• Verify the fistula is a complication of the rectosigmoiditis, not an independent finding or related to Crohn's disease.
• Consider additional codes for the specific type or location of the fistula if further detail is provided (e.g., perianal fistula).