Varicose veins are not difficult to understand, but varicose veins are divided into primary varicose veins and secondary varicose veins. Primary varicose veins of the lower extremities, also known as simple varicose veins, are a disease that is confined to the superficial venous system of the lower extremities and is the most common type in clinical practice. Here, primary varicose veins are first introduced to you. Why are there primary varicose veins in the lower extremities? First of all, it is important to understand that there are three types of blood vessels in the human body: veins, arteries, and capillaries. Among them, venous valves are present in veins. Here, you can temporarily think of the venous valve as a one-way open gate. The venous blood flow in the lower extremities is from bottom to top, and during normal reflux, the venous valve opens and blood flows through, as in the picture above (left). After the blood flow passes, it will return downward because of the presence of gravity and other factors, and at this time, the venous valve closes to prevent the return of venous blood flow, as shown above (center). Once the venous valve function is impaired, resulting in incomplete closure, which in turn causes the venous blood flow to return downward, as shown in the figure above (right). The reflux of venous blood causes a thinning of the lower venous wall, which leads to the appearance of the varicose vein masses seen in everyday life. What are the causes of primary lower extremity varicose veins? Weakness of the venous wall, venous valve defects and elevated pressure within the superficial veins are the main causes of superficial varicose veins. Varicose veins in the lower extremities mostly occur in people who are engaged in permanent standing work, high intensity of physical activity or are sedentary and less active. Various causes of venous vasodilatation, weakened calf muscle pump, and venous valve insufficiency can lead to downward regurgitation of blood flow in lower extremity veins, and once regurgitation occurs, varicose veins are easily caused. The main factors of varicose veins of lower limbs are: 1, long-term standing work: long-term standing work, due to the relationship of gravity can cause the lower limb veins blood reflux difficulties, over time will lead to thickening of the venous lumen, once the venous lumen thickening to the extent that the venous valve can not be completely closed, and will further aggravate the venous blood downward reflux. 2, heavy physical labor: long-term heavy physical labor can cause the increase of lower limb venous pressure. 3, tall, thick and obese: due to obesity, resulting in the increase of gravity, the lower limb venous blood reflux is affected. 4.Increased abdominal pressure and pregnancy: increased abdominal pressure can affect the reflux of lower limb veins, and any factors that lead to increased abdominal pressure can cause the occurrence of varicose veins in lower limbs. After women’s pregnancy, in addition to increased abdominal pressure, the enlarged uterus can compress the iliac vein and obstruct the return flow of blood to the lower limbs, causing varicose veins in the lower limbs. 5, other factors: including dietary habits, sedentary work.