Objective: Venous reflux is the sole pathophysiologic process in primary chronic venous disease and its progression. We hypothesize that the reflux volume (RV) increases along a great saphenous vein (GSV) in a distal direction. We aimed to compare simultaneously measured RV in the upper and lower GSV segments in a thigh.

Methods: Patients meeting the inclusion criteria were enrolled (70 limbs of patients with primary incompetence of the GSV) and consented to this participate in the single-center study. Patients were stratified into two groups: incompetent terminal valve and competent terminal valve. A cross-section area of the GSV was measured at the upper (CSA1, cm2) and distal (CSA2, cm2) points in a thigh. A cross-section area of each tributary that joined with the GSV between the points was measured, and their total cross-section area was calculated (CSAtrib). After a distal cuff compression-decompression maneuver, a time average mean velocity (cm/s) and reflux duration (seconds) were measured at both points simultaneously. The RV (mL) was calculated for each point (RV1 and RV2). The difference in absolute values of ΔRV (mL) and its relative changing (ΔRV, %) were calculated.

Results: The main result was RV increases caudally from saphenofemoral junction (SFJ) to the knee level (RV1 12.7 ± 8.4 and RV2 20.5 ± 14.0 mL; P < .0001). There was no difference between CSA1 and CSA2 (0.34 ± 0.17 and 0.33 ± 0.17 cm2, respectively; P = .9) but the time average mean velocity was a statistically significant different in two points (7.3 ± 3.9 and 11.4 ± 5.7 cm/s, respectively; P < .0001). All of the tributaries between the points were competent.

Conclusions: The RV in the GSV increases caudally from SFJ to the knee level. The observed RV was an aggregate of all GSV tributaries' flow and the flow via the SFJ if incompetent.