ICD-10 Code I80.21 – Phlebitis and thrombophlebitis of iliac vein (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I80.21 – Phlebitis and thrombophlebitis of iliac vein
What it is
I80.21 identifies inflammation of the iliac vein with associated clot formation. Use it when documentation states phlebitis or thrombophlebitis involving the iliac vein, usually on one side.
Clinical signs
Clinical features vary; refer to documentation. Commonly, records describe pelvic or lower-extremity venous thrombosis, pain, swelling, tenderness, or imaging-confirmed clot in the iliac vein.
When to use this code
Use this code when the provider specifically documents phlebitis or thrombophlebitis of the iliac vein. It also fits when imaging or specialist notes confirm iliac vein thrombosis and the site is recorded as the iliac vein.
If laterality is documented, report the appropriate side-specific code. Check documentation when the note only says deep vein thrombosis, venous clot, or pelvic thrombosis without naming the iliac vein.
Do not use for
Do not use I80.21 for superficial thrombophlebitis, unspecified venous thrombosis, or clots in other lower-extremity veins. Check documentation if the iliac vein is not clearly identified.
Coding tip
Code the exact vein named in the record; if the iliac vein is not specified, query before assigning I80.21.