| Uncomplicated venous disease (C0-3) | 
|---|
| Clinical category C0 | Normal findings, nothing suggestive of venous disease | 
| Clinical category C1 | Telangiectasia or intradermal reticular veins | 
| Clinical category C2 | Varicose veins, no swelling, no skin changes ascribed to venous disease | 
| Clinical category C3 | Varicose veins, swelling, no skin lesions ascribed to venous disease | 
| Complicated venous disease (C4-6) | 
|---|
| Clinical category C4 | Skin changes ascribed to venous disease: hyperpigmentation, eczema, lipodermatosclerosis | 
| Clinical category C5 | Skin changes ascribed to venous disease and healed venous ulcer | 
| Clinical category C6 | Skin changes ascribed to venous disease and active venous ulcer |