Duplex sonography of venous stasis.

The major reasons for venous thrombosis are inflammation, increased blood coagulability, and blood stasis. Investigation of these processes in vivo in a particular vein is difficult. Blood stasis in the peripheral veins is assumed to increase the risk of thrombosis during immobilization. By duplex sonography the authors were able to demonstrate different echogenicity in single veins of the lower limb in healthy subjects in a sitting position. Of 25 subjects, 7 presented a high echogenicity of the venous blood similar to that of the surrounding tissue. An additional 5 subjects presented this phenomenon after venous blood flow was stopped by a pressure cuff. The remaining 13 subjects still presented a dark lumen of the veins. Duplex sonography can discriminate different compositions of resting venous blood associated with venous stasis. Whether these findings correlate with an increased risk of thrombosis is not known.