ICD-10 Code K64.5 – Perianal venous thrombosis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K64.5 – Perianal venous thrombosis
What it is
K64.5 identifies a thrombosed vein at the anal margin, often described as a painful perianal lump. It is a specific hemorrhoidal condition rather than a general anal pain diagnosis.
Clinical signs
Common findings include sudden localized pain, swelling, and a tender bluish or purple perianal nodule. Clinical features vary; refer to documentation.
When to use this code
Use K64.5 when the provider documents perianal venous thrombosis, thrombosed external hemorrhoid, or a thrombosed perianal venous lesion. Code it from the final diagnosis, not from symptoms alone. If the record only says rectal pain or anal swelling, check documentation.
Do not use for
Do not use this code for internal hemorrhoids, uncomplicated hemorrhoids, or nonspecific anal discomfort. If the note does not clearly identify a thrombosed perianal vein, verify the diagnosis before coding.
Coding tip
Match the code to the provider’s exact wording, and query if the chart says “hemorrhoid” without documenting thrombosis.