Great saphenous vein diameter at the saphenofemoral junction and proximal thigh as parameters of venous disease class.

BACKGROUND: Great saphenous vein (GSV) incompetence is involved in the majority of cases of varicose disease. Standardised pre-interventional assessment is required to analyse the relative merit of treatment modalities. We weighed GSV diameter measurement at the sapheno-femoral junction (SFJ) against measurement at the proximal thigh 15 cm distal to the groin (PT), established a conversion factor and applied it to selected literature data.

METHODS: Legs with untreated isolated GSV reflux and varices limited to its territory and control legs were studied clinically, with duplex ultrasound and photoplethysmography. GSV diameters were measured at both the SFJ and the PT. A conversion factor was calculated and used to compare published data.

RESULTS: Of 182 legs, 60 had no GSV reflux (controls; group I), 51 had above-knee GSV reflux only (group II) and 71 had GSV reflux above and below knee (group III). GSV diameters in group I measured 7.5 mm (± 1.8) at the SFJ and 3.7 mm (± 0.9) at the PT. In groups II and III, they measured 10.9 mm (± 3.9) at the SFJ and 6.3 mm (± 1.9) at the PT (p < 0.001 each). Measurement at the PT revealed higher sensitivity and specificity to predict reflux and clinical class. Good correlation between sites of measurement (r = 0.77) allowed a conversion factor (SFJ = 1.767 * PT, PT = 0.566*SFJ) to be applied to pre-interventional data of published studies.

CONCLUSIONS: GSV diameter correlates with clinical class, measurement at the PT being more sensitive and more specific than measurement at the SFJ. Applying the conversion factor to published data suggests that some studies included patients with minor disease.