ICD-10 Code I80.209 – Phlebitis and thrombophlebitis of unspecified deep vessels of unspecified lower extremity (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I80.209 – Phlebitis and thrombophlebitis of unspecified deep vessels of unspecified lower extremity
What it is
This code identifies inflammation and clotting in a deep vein of the lower leg or thigh when the exact vessel and side are not documented. Use it for deep vein thrombosis involving an unspecified lower extremity.
Clinical signs
Typical findings include unilateral leg swelling, pain, tenderness, warmth, or redness. Clinical features vary; refer to documentation, and confirm the provider has identified a deep vein process rather than a superficial vein problem.
When to use this code
Use I80.209 when the record states phlebitis or thrombophlebitis of a deep vein in the lower extremity but does not specify left or right. It also fits when the note confirms deep venous involvement without naming the exact vessel. Check documentation if the encounter describes an acute clot, chronic history, or another venous disorder.
Do not use for
Do not use this code for superficial thrombophlebitis, varicose veins, or venous insufficiency without deep vein involvement. If the chart specifies a different vein, laterality, or a more specific DVT code, code that instead.
Coding tip
Look for laterality and whether the provider documented deep versus superficial venous disease before assigning this unspecified code.