Despite the many studies on venous haemodynamics using duplex, only a few e
valuated the normal values, variability and reproducibility. Therefore, the
range and variability of venous diameter, compressibility, flow and reflux
were measured. To obtain normal values, 42 healthy individuals (42 limbs,
714 vein segments) with no history of venous disease were scanned by duplex
. To determine the reproducibility the intra-observer variability was measu
red in I I healthy individuals (187 vein segments) and the inter-observer v
ariability in 15 healthy individuals (255 vein segments) and 13 patients (1
69 vein segments) previously diagnosed with deep venous thrombosis. Of the
714 normal vein segments, 708 (99%) were traceable, including the crural ve
ins. Of the traceable vein segments, 675 (95%) were compressible and in 696
(98%) flow was present. Of the 42 common femoral vein segments, in 25 (60%
) the reflux duration exceeded 1.0 s, but in the other proximal vein segmen
ts the reflux duration was less than 1.0 s (95% confidence interval 3.0-10.
0). With the exception of the distal long saphenous vein, in the distal vei
n segments the reflux du ration was less than 0.5 s (95% confidence interva
l 3.5-8.2). The coefficient of variation of the diameter measurements range
d from 14 to 50% and that of the reflux measurements from 28 to 60%. The ka
ppa-coefficient of the inter-observer variability in the classification of
compressibility measurements in the patients was 0.77 and that of the reflu
x measurements was 0.86. This study shows that almost all veins were compre
ssible in healthy individuals, except the distal femoral veins. In healthy
individuals the duration of reflux of the proximal veins was less than 1.0
s and in the distal veins it was less than 0.5 s. The inter-observer variab
ility of the reflux and compressibility measurements in the patients was go
od.