Final answer:
Varicose veins are the most common cause of chronic venous insufficiency (CVI). They occur when the valves in the veins become ineffective, leading to blood pooling and stretching of the veins. Varicose veins are influenced by factors such as age, gender, family history, and certain risk factors.
Step-by-step explanation:
The most common cause of chronic venous insufficiency (CVI) is varicose veins. Varicose veins occur when the valves in the veins become ineffective, causing blood to pool and stretch the veins. They are most common in older adults, females, and people with a family history of the condition. Risk factors such as obesity, pregnancy, standing for long periods, chronic constipation, and long-term alcohol consumption can increase the risk of developing varicose veins.