Calf vein anatomy and flow: implications for colour Doppler imaging

Early experience has suggested that colour flow Doppler ultrasound may have a diagnostic role in calf vein thrombosis. Before its accuracy within the calf can be adequately assessed, normal calf vein flow and anatomy needs to be understood. We, therefore, studied 40 normal volunteers, age range 24-75 years (mean 45.4), M:F 22:18, and assessed both flow and venous diameter in each of the three sets of calf veins in the supine and erect positions and once again in both these positions following the application of an above knee band. Paired sets of veins were present in all posterior tibial and common peroneal sets, but in only 85% of the anterior tibial group. Significant flow variations were present between different sets of veins, there being relatively less appreciable flow within the common peroneal (p < 0.05). Both band application and erect posture produced significant increases in venous diameter (p < 0.01, p < 0.001) in the posterior tibial and common peroneal veins, aiding visualization but at the cost of reducing flow following band application (p < 0.05, p < 0.01). The erect posture had no deleterious effect on calf vein flow. We, therefore, recommend that when the patency of calf veins is being assessed scanning should be performed in both a supine and erect position as this will help vein visualization without a reduction in flow, and thus avoid misinterpretation.