ICD-10 Code I80.29 – Phlebitis and thrombophlebitis of other deep vessels of lower extremities (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I80.29 – Phlebitis and thrombophlebitis of other deep vessels of lower extremities
What it is
I80.29 identifies inflammation and clotting in deep veins of the lower leg or thigh when the specific vessel is not otherwise named. Use it for deep venous thrombophlebitis outside the more specific lower-extremity codes.
Clinical signs
Typical findings include unilateral leg pain, swelling, tenderness, warmth, or redness. Clinical features vary; refer to documentation, and confirm that the affected vessel is a deep lower-extremity vein.
When to use this code
Use this code when the provider documents phlebitis or thrombophlebitis in an unspecified deep vessel of the lower extremity and no more specific site is named. It also fits cases where the record clearly supports deep venous involvement but does not identify a named vein. Check documentation for laterality and acuity if reported elsewhere.
Do not use for
Do not use it for superficial thrombophlebitis or for deep vein thrombosis coded to a more specific lower-extremity site. If the chart names another vessel or a different condition, code that diagnosis instead.
Coding tip
Look for the exact vein and whether the provider documented deep versus superficial involvement before assigning I80.29.