ICD-10 Code K60.421 – Rectal fistula, complex, initial (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K60.421 – Rectal fistula, complex, initial
What it is
This code identifies a complex fistula involving the rectum. It is used when the record specifies the condition as complex and the encounter is initial.
Clinical signs
Clinical features vary; refer to documentation. Typical findings may include persistent drainage, local pain, recurrent infection, or an abnormal tract on exam or imaging.
When to use this code
Use K60.421 when the provider documents a rectal fistula as complex and this is the initial encounter for that condition. Confirm the anatomic site and complexity in the note, operative report, or specialist assessment. If the documentation does not clearly state “complex,” check documentation.
Do not use for
Do not use this code for a simple rectal fistula, a healed condition, or follow-up care after the initial encounter. If the record describes a different anorectal fistula or does not specify rectal involvement, verify the diagnosis.
Coding tip
Match the code to both the site and the documented encounter type; “complex” and “initial” must be explicitly supported.