The veins have one-way valves so that the blood can travel in only one direction. The valves may get weaker if the walls of the vein become stretched and less flexible (in-elastic). A weakened valve can allow blood to leak backward and eventually flow in the opposite direction. When this occurs, blood can accumulate in the vein(s), which then become enlarged and swollen.
Any condition that puts pressure on the abdomen has the potential to cause varicose veins; for instance,
- Tumors (rare case)
Some potential risk factors include:
- Age over 50
- Standing for long periods
- Family history of varicose veins
- Use of birth control pills