Because of gravity, water always flows lower. In the human body, blood is pumped out by the heart to the arteries, transported throughout the body, and returned to the heart through the veins. So in an upright human body, venous blood is able to overcome gravity and return from the lower extremities to the higher heart, which relies on a secret weapon, the venous valves. The venous valve is one of the signs that distinguish veins from arteries, usually bilobed, like a two-door door, slender, soft, and sensitive to opening and closing activities. It is distributed throughout the body, with the highest density in the veins of the lower extremities. However, not all veins have valves, for example, the portal vein does not. How do venous valves work? In the lower extremities, for example, our lower legs act as a pressure pump: when the muscles contract, the resulting high pressure drives venous blood back toward the heart; when the muscles relax, the valves close, preventing blood from flowing back into the legs. Closure of the valve also creates a negative pressure that drives blood from the superficial veins into the deep veins, which increases blood flow back to the heart even further. How do you assess whether a venous valve is working properly? The duration of regurgitation is measured by ultrasound, which is used clinically as an indicator of valve function, by having the patient stand with a deep inspiration followed by a sudden breath hold. In general, the duration of lower extremity venous regurgitation is less than 0.5 seconds in 80-90 % of normal people, and more than 0.5 seconds in 10-20 % of people. Valve regurgitation of greater than 1 second can be considered in conjunction with clinical consideration of valve insufficiency. What causes abnormal venous valve function? 1. congenital absence or weakness; 2. ageing that relaxes the vein wall and valves; 3. prolonged increased venous pressure: including obesity, pregnancy, heavy work, congenital or acquired iliac vein stenosis/occlusion; 4. deep vein thrombosis followed by inflammatory material and scarring that disrupts the structure of the venous valves. Superficial venous valve insufficiency Valve insufficiency occurs in the superficial veins of the lower extremities and can lead to varicose veins. It tends to occur first in the saphenofemoral valve, which is most likely to be involved in saphenous varicose veins because of its highest position, superficial anatomic location, and lack of muscle protection. In a small percentage of cases, valve failure occurs at the sapheno-N venous junction (N fossa location), resulting in small saphenous varicose veins. The location of the lesion is easily understood with ultrasound localization Long-term varicose veins can lead to skin pigmentation, ulcer formation, and other nutritional changes in the calf skin. Ultrasound findings in such cases often have multiple segments with varying degrees of simultaneous valve insufficiency, including the traffic veins. Deep venous valve insufficiency Deep venous valve insufficiency includes primary and secondary. Its pathogenesis is complex and will not be discussed in detail in this article. One point worth making is that early deep venous valve insufficiency can be treated by targeting the problematic superficial veins, but some patients still develop recalcitrant ulcers. Deep vein valve repair should be considered only if deep vein obstruction (iliac vein stenosis or occlusion and thrombosis) is ruled out and if deep vein valve pathology does exist and repair is anticipated. This type of surgery is costly, has many complications, and the results are not guaranteed; it is not yet widely accepted and recognized internationally, and it is hoped that with the development of medicine, more effective treatment modalities with fewer complications will emerge.