ObjectiveTo 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 singularly or in combination. MethodsWe scanned by the means of the same color Doppler ultrasound protocol 3000 lower limbs in 1500 consecutive patients, affected by symptomatic chronic venous insufficiency from 2013 to 2023. Limbs with normal venous function, incomplete scans, or that were affected by post-thrombotic syndrome, pelvic reflux, isolated perforator reflux, venous malformation, phlebolymphedema and Clinical, Etiological, Anatomical, Pathophysiological clinical class C5 and C6 were excluded from the final analysis. ResultsOverall, 1072 patients—252 (23.5%) males and 820 (76.5%) females (P < .0001) matched for age (P = .692)—were included in the study for a total of 1956 limbs affected by primary chronic venous insufficiency, clinical class C2 to C4. The main finding was the significant prevalence of varicose networks fed by reflux of the AASV alone (odds ratio [OR], 1.96; 95% confidence interval [CI], 1.26-3.06; P = .001) or combined with GSV (OR, 1.84; 95% CI, 1.34-2.52; P = .0002) in females. In contrast, GSV insufficiency alone was significantly prevalent in males (OR, 0.54; 95% CI, 0.43-0.68; P < .0001). No significant sex differences regarding SSV reflux were detected. Moreover, we considered the presence of competent terminal valve (TV+) at the level of the saphenofemoral junction, which resulted more significantly present in female (OR, 1.57; 95% CI, 1.12-2.19; P = .0083); to the contrary incompetent terminal valve (TV−) was more common in males (OR, 0.64; 95% CI, 0.46-0.89; P = .0083). Finally, considering reflux in the AASV territory in the presence of a TV+, a strong prevalence in females was detected (OR, 2.28; 95% CI, 1.48-3.52; P = .0002), whereas males developed reflux along the GSV when a concomitant TV− was present (OR, 0.62; 95% CI, 0.41-0.94; P = .0244). ConclusionsThe analysis of the lower limb varicose networks highlights that reflux along the AASV alone, in presence of a TV+ at the junction or coupled with GSV insufficiency, is more prevalent in females. In contrast, GSV resulted the main trunk feeding varicose veins in males, in particular when a TV− was detected. Our findings suggest that females could be more prone to developing varicose veins with an ascending mechanism, whereas in males the descending one seems to be more common.