ICD-10 Code I80.20 – Phlebitis and thrombophlebitis of unspecified deep vessels of lower extremities (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I80.20 – Phlebitis and thrombophlebitis of unspecified deep vessels of lower extremities
What it is
I80.20 identifies inflammation and clotting in a deep vein of the lower leg or thigh when the exact vein is not specified. Use it when documentation confirms deep venous thrombophlebitis but does not name the vessel.
Clinical signs
Typical findings include unilateral leg pain, swelling, warmth, tenderness, and sometimes redness. Clinical features vary; refer to documentation, and confirm that the provider documented a deep venous process rather than a superficial one.
When to use this code
Use this code when the record states phlebitis, thrombophlebitis, or DVT in a deep lower-extremity vein, but the specific vessel is not identified. It also fits when imaging or assessment supports deep venous involvement and the note remains nonspecific. Check documentation if laterality or vein location is clarified.
Do not use for
Do not use I80.20 for superficial thrombophlebitis or for deep vein disease in another body site. If the chart specifies a particular vein or a different lower-extremity deep vessel code, choose the more exact code.
Coding tip
Assign the most specific thrombophlebitis code available, and query for laterality or vein details when the documentation is incomplete.