This document discusses various investigations used to detect and assess venous insufficiency and plan interventions. Duplex ultrasound with Doppler is the preferred initial imaging method as it can identify the etiology, anatomy, and source of reflux to guide treatment planning. Other non-invasive options include plethysmography, CT venography, and MR venography. Invasive tests like phlebography and intravascular ultrasound may be used when deeper vein abnormalities are suspected. Duplex scanning is usually sufficient to evaluate and manage most varicose veins but other imaging can help in complex cases.