The diagnosis of venous disease has been transformed by advances in vascular imaging over the past three decades. Where clinical assessment alone once had to suffice — with its inherent limitations in distinguishing between different venous pathologies — contemporary vascular medicine has access to a suite of non-invasive imaging tools that can map the venous anatomy with extraordinary precision. Understanding what these tests can reveal helps patients appreciate why investigation is worthwhile and what to expect from the diagnostic process.
The cornerstone of venous investigation is duplex ultrasound — a combination of conventional B-mode ultrasound, which creates anatomical images of the veins, with Doppler technology, which measures the velocity and direction of blood flow within them. In experienced hands, duplex ultrasound can identify venous valve incompetence, map the distribution of venous reflux, detect and characterize deep vein thrombi, and assess the hemodynamic significance of venous disease with excellent accuracy.
During a duplex ultrasound examination for venous insufficiency, the sonographer places the transducer over the major superficial and deep veins of the leg, compressing them gently and applying Doppler assessment. Normal veins collapse completely under gentle compression and show no backward blood flow. Incompetent veins fail to collapse normally and demonstrate pathological reflux on Doppler assessment — blood flowing backward through the failed valve. This information allows the vascular team to map exactly which veins are contributing to the patient’s symptoms.
For the investigation of suspected deep vein thrombosis, compression ultrasound has become the primary diagnostic test. A deep vein containing a thrombus will not compress under ultrasound probe pressure because the clot within prevents the vein walls from meeting. This simple, reproducible finding has replaced the invasive venography that was previously required for DVT diagnosis, making the evaluation accessible, comfortable, and rapidly available in most hospital settings.
Additional investigations are sometimes employed for specific clinical questions — CT venography for the assessment of pelvic vein anatomy, magnetic resonance imaging for vein assessment in pregnant patients avoiding radiation, and blood tests for thrombophilia evaluation in patients with unexplained or recurrent DVT. But for the majority of patients presenting with leg swelling or venous symptoms, duplex ultrasound provides all the information needed to establish a diagnosis and plan treatment. Vascular specialists encourage any patient with persistent or unexplained leg swelling to request this investigation.