[Venous reflux: Measurement variability due to positional differences].

Purpose: The purpose of this study was to evaluate the role of the subject's position and two different maneuvers in the reflux measurements in femoral veins.
Materials and Methods: Venous reflux times in the common femoral vein (CFV) and superficial femoral vein (SFV) were studied in 50 healthy subjects (25 women, 25 male) aged between 22-57 years-old while the subjects were in supine and standing positions. Reflux was provocated only by Valsalva maneuver (VM) when the subject was lying down, whereas it was provocated by (1) Valsalva maneuver and (2) compression and release maneuver, respectively, when the subject was standing. Reflux times were recorded with each of the three methods.
Results: Regarding CFV, a reflux time of 1 second or more was recorded in 29 limbs (29%) only in the supine position. Of these 29 measurements, 19 were between 1 and 1.9 sec and 8 between 2 and 2.9 sec. When the subjects were examined in the standing position, the prevalence of reflux lasting more than 1 sec substantially decreased (5%). The prevalence of reflux lasting less than 0.5 sec was 97% with standing compression maneuver, 84% with standing VM and 27% with supine VM. Similarly, prevalence of reflux of longer than 0.5 sec or 1 sec was lower in the standing position than in the supine position in SFV. In CFV, mean reflux time was 1.3 sec in the supine position, whereas it was 0.7 sec and 0.4 sec with standing compression and standing Valsalva maneuvers, respectively. Corresponding values in SFV were 0.5 sec, 0.3 sec and 0.2 sec, respectively.
Conclusion: The probability of making a false positive diagnosis of pathological reflux is high with supine examinations. When an examination in the supine position reveals a reflux time of longer than 1 second, making the patient stand up is expected to yield more reliable results. Compression and release maneuver, with its lowest false positive reflux prevalence, is the most reliable method in the evaluation of venous insufficiency.