ICD-10 Code I80.259 – Phlebitis and thrombophlebitis of unspecified calf muscular vein (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I80.259 – Phlebitis and thrombophlebitis of unspecified calf muscular vein
What it is
This code identifies inflammation and clot formation in a calf muscular vein, but the specific calf vein is not named. Use it when the record clearly states thrombophlebitis in an unspecified calf muscular vein.
Clinical signs
Typical findings include localized calf pain, tenderness, swelling, warmth, or a palpable cord. Clinical features vary; refer to documentation, and confirm that the provider documents a calf muscular vein involvement.
When to use this code
Use this code when the diagnosis specifically documents phlebitis or thrombophlebitis affecting an unspecified calf muscular vein. It is appropriate when the site is in the calf but the exact muscular vein is not identified. Check documentation if the note only says deep vein thrombosis or superficial thrombophlebitis.
Do not use for
Do not use it for thrombosis in a named leg vein, upper-extremity veins, or nonspecific DVT without calf muscular vein documentation. Check documentation if the record does not clearly localize the vein.
Coding tip
Code the documented vein location exactly; unspecified calf muscular vein should be used only when the provider does not name a more specific calf vein.