How is venous insufficiency evaluated sonographically?
Venous insufficiency is most commonly due to valvular damage from a DVT. In the lower extremities, venous insufficiency is best assessed sonographically with the patient in the upright position with provocative maneuvers (i.e., Valsalva and calf squeezing). Color spectral Doppler waveforms are obtained of both deep and superficial veins to the level of the knee. Normally, after calf squeezing, flow in the veins is antegrade with a very short period of flow reversal as returning blood closes the first competent venous valve. In contrast, insufficient veins will have a longer and greater degree of flow reversal (i.e., >2 sec). The time used to quantify abnormal flow reversal is institution dependent and needs to be validated at each institution.