ICD-10 Code K60.521 – Anorectal fistula, complex, initial (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K60.521 – Anorectal fistula, complex, initial
What it is
This code identifies a complex anorectal fistula during the initial encounter. It means an abnormal tract connects the anal or rectal area to nearby tissue and is considered complex based on documentation.
Clinical signs
Common findings include persistent drainage, pain, local irritation, or recurrent perianal infection. Clinical features vary; refer to documentation, especially when notes describe branching tracts, multiple openings, or involvement of deeper structures.
When to use this code
Use K60.521 when the record clearly states a complex anorectal fistula and the encounter is initial. This is appropriate for first visits, new evaluations, or initial management before subsequent care is documented. Check documentation if complexity is not specified.
Do not use for
Do not use this code for a simple anorectal fistula or for follow-up encounters after the initial visit. If the note describes another anal disorder without a fistula, code the documented condition instead.
Coding tip
Confirm both “complex” and “initial” in the provider note before assigning K60.521.