To determine the sex prevalence of lower limb varicose networks fed by reflux of the great saphenous vein (GSV), anterior accessory saphenous vein (AASV) and small saphenous vein (SSV) singularly or in combinations. We scanned by the means of the same Colour Doppler Sonography (CDS) protocol 3000 lower limbs in 1500 consecutive patients, affected by symptomatic chronic venous insufficiency (CVI) during the decade 2013-2023. Limbs with normal venous function, incomplete scans or affected by post thrombotic syndrome, pelvic reflux, venous malformation, phlebolymphedema and CEAP clinical class C5-C6 were excluded from the final analysis. Overall, 1072 patients, 252 (23.5%) males and 820 (76.5%) females (p<0.0001), matched for age (p=0.692), were included into the study for a total of 1956 limbs affected by primary CVI, clinical class C2-C4. The main finding was the significant prevalence of varicose networks fed by reflux of the AASV alone (OR 1.96, CI 1.26-3.06, p=0.001) or combined with GSV (OR 1.84, CI 1.34-2.52, p=0.0002) in females. On the other hand, GSV insufficiency alone was significantly prevalent in males (OR 0.54, CI 0.43-0.68, p<0.0001). Moreover, we considered the presence of competent terminal valve (TV+) at the level of the sapheno-femoral junction, which resulted more significantly present in female (OR 1.57, CI 1.12-2.19, p=0.0083); to the contrary incompetent terminal valve (TV-) was more common in males (OR 0.64, CI 0.46-0.89, p=0.0083). Finally, considering reflux in the AASV territory in presence of a TV+, a strong prevalence in females was detected (OR 2.28, CI 1.48-3.52, p=0.0002), while males developed reflux along the GSV when a concomitant TV- was present (OR 0.62, CI 0.41-0.94, p =0.0244). The analysis of the lower limb varicose networks highlights that reflux along the AASV alone, in presence of a competent terminal valve at the junction, or coupled with GSV insufficiency, is more prevalent in females. On the other hand, GSV resulted the main trunk feeding varicose veins in males, in particular when an incompetent terminal valve was detected. Our findings suggest that females could be more prone to develop the varicose vein with an ascending mechanism, whereas in males the descending one seems more common.