Comment to: Great saphenous vein diameter at the saphenofemoral junction and proximal thigh as parameters of venous disease class, by Mendoza E, Blättler W, Amsler F. Eur J Vasc Endovasc Surg 2013;45:76-83.

The aim of this study was to investigate a possible correlation of GSV diameters measured at the SFJ and the proximal thigh (PT) with the importance of the venous disorder. Between October and December 2009. 844 legs were screened and 182 legs included in the survey (CEAP C1-C5). The criterion for patient inclusion was the presence of a GSV reflux beginning at the terminal or the preterminal valve and escaping through a mid-thigh branch vein (above knee reflux, -51 legs- group II) or escaping through a lower leg branch vein (above and below knee reflux-71 legs-, group III). Legs with varices but no GSV were recruited as controls (-60 legs- group I).
Vein diameters were measured holding the probe transversely with no pressure at the SFJ distal to the terminal valve and 15 cm below the junction. Measurement of GSV vein diameter at the SFJ is challenging for the curvature of the inguinal GSV, the presence of epigastric, pudendal and accessory veins and eventual aneurysmatic dilatations. The PT site 15 cm below the SFJ, chosen by CHIVA Group members, is located in the truncal portion of GSV where the vein is cylindrical and largely devoid of joining branches, so well accessible, and diameter measurements can be taken reliably.
GSV diameters in all groups, measured at both sites, were not related with patients’ age and sex or calf muscle-pump function. Modest correlations were found with body weight and BMI but not with height. GSV diameters in controls (group I) measured 7.5 mm (±1.8) at the SFJ and 3.7 mm (±0.9) at the PT. In patients with GSV reflux (groups II and III), they measured 10.9 mm (±3.9) at the SFJ and 6.3 mm (±1.9) at the PT, respectively. Vein diameters were larger in the presence of reflux, compared with its absence, by an average of 3.4 mm at the SFJ and 2.6 mm at the PT. No difference in diameters was found between group II and group III. Thus, the degree of vein dilatation was independent of the length of reflux above knee only versus above and below knee.
A GSV diameter above the 2 SD margin of group I legs was found in 2% in group I at either point of measurement. In groups II and III, a significantly different prevalence was observed when measurements made at the SFJ and PT, respectively. The 2 SD margin was exceeded by 43% of patients when measured at the SFJ and by 62% when measured at the PT. A mathematical formula was developed to mutually convert measurements taken at the SFJ and the PT, used to revise published data.

Conversion PT to SFJ (95% CI 1.698–1.836): diameter SFJ (mm) = 1.767 × diameter PT (mm)

Conversion SFJ to PT (95% CI 0.544–0.548): diameter PT (mm) = 0.566 × diameter SFJ (mm)

Measurement at the PT as compared to measurement at the SFJ demonstrated higher accuracy and both higher sensitivity and specificity for venous disease class as well as for prediction of reflux. GSV diameter, venous hemodynamic (PPG refilling times) and clinical disease class did not differ whether reflux was above knee only or above and below knee. Diameter assessment at the PT seems suitable for stratification of patients allocated to future interventional trials as well as for outcome evaluation.