Prospective comparison of duplex scanning and descending venography in the assessment of venous insufficiency.

A prospective study comparing duplex scanning and descending venography was applied to 143 venous segments in 25 extremities with moderate to severe manifestations of chronic venous insufficiency (class 2 or 3). Duplex scanning was performed with the patient in the 15 degree reverse Trendelenburg position, and descending venography with the patient in the 60 degrees semi-erect position; the Valsalva maneuver was used to elicit reflux in both tests. The duplex parameter of reflux duration greater than 0.5 second correlated with venographic reflux in 94 of 105 segments (sensitivity of 90%). Conversely, reflux time less than or equal to 0.5 second correlated with venographic competence in 32 of 38 segments (specificity of 84%). A total of 17 discrepancies were identified among the 143 total segments studied, for an accuracy of 88%. The largest proportion of discrepancies was identified in the group with venographic competence and reflux duration greater than 0.5 second and less than or equal to 2.0 seconds; this was designated a gray zone. Mean peak velocities were significantly higher in the reflux group when compared with the competence group in the profunda femoris vein (p = 0.047), greater saphenous vein (p less than 0.001), popliteal vein (p less than 0.001), and tibial vein (p = 0.005). We conclude that venographic reflux correlates best with duplex scan findings of reflux duration greater than 0.5 second. Duration of reflux greater than 0.5 second and less than or equal to 2.0 seconds, however, represents a gray zone and should be interpreted with caution since this could lead to over-reading of reflux disease, in which case verification of incompetence by descending venography may be indicated.