Table 1 Clinical classification (C) according to CEAP Class Clinical signs C0 No visible or palpable signs of venous incompetence C1 Spider veins and/or reticular varices C2 Varicose veins C3 Oedema C4a Pigmentation, eczema C4b Atrophie blanche, dermatoliposclerosis C5 Cured venous leg ulcer C6 Active venous leg ulcer in CEAP stage C2, developed progression to CVI [13]. Recommendation 13 An imaging technique shall be used in the context of standardised phlebological diagnosis. The first-choice method shall be duplex ultrasound. If necessary, vein function shall also be measured (e.g., PPG/LRR or VOP). Recommendation 15 Complete, traceable documentation of the findings shall be kept. Recommendation 16 Pathological findings from technical examinations should be tested for clinical significance. Recommendation 139 Invasive treatment of varicose veins during pregnancy should be indicated only in exceptional cases.