Varicose veins are a common health condition and experienced by over 30% of adults. This page describes the causes of varicose veins and the conditions or factors which may lead to the development of varicose veins. However, before these can be understood, you will need to know a little bit about veins and the part they play in the circulatory system.
Symptoms of varicose veins are tired, heavy legs, swollen ankles and mild itching of the skin. In addition, complications such as varicose eczema and varicose ulcers may occur.
Veins, like arteries and capillaries, are blood vessels and part of the circulatory system.
Arteries supply organs with blood and possess thick walls to handle the pressure within them as blood is pumped with force out of the heart with each heartbeat. Veins have the job of returning blood back to the heart and lungs once it has delivered oxygen around the body. They operate under much lower pressure and have thinner walls. Capillaries connect arteries to veins.
Three types of veins can be found in the legs:
- Superficial leg veins lie just below the surface of the skin and carry about 10% of the blood returning from the legs. You may sometimes see these veins even if they are normal. Superficial veins are the ones that develop into varicose veins
- Deep leg veins lie inside the leg and are surrounded by muscles and connective tissue. They carry the rest of the blood returning from the leg to the heart
- Perforator veins (small communicating veins) connect superficial leg veins to the deep leg veins.
Of all the veins in the body, veins in the legs have the hardest job. This is because for more than half of our life (when one is standing or sitting), blood in the legs has to flow against the force of gravity. To help this process along and prevent blood lying in a pool at your ankles, small valves are found every 8 to 10 cm inside superficial and deep leg veins. These help drive the flow of blood in one direction – towards the heart.
For a number of reasons (described below), veins can lose their elasticity, stretch or become enlarged. This causes valves to leak, allowing blood to flow backwards towards the feet. The vein swells with extra blood and over time, this causes further damage to the valves making the situation worse.
Extra blood and fluid in the swollen vein starts to seep into the surrounding tissue and this gives rise to symptoms of varicose veins such as tiredness, heaviness of legs and swollen ankles. If the condition is longstanding, tissue cells become damaged leading to complications.
It is estimated that around 3 in 10 people may develop varicose veins in their lifetime. The condition occurs in both sexes but appears to be more common in women, probably because of the effect of the female hormones. The tendency to develop varicose veins appears to run in families.
Although varicose veins may occur at any age, they become more common as one gets older. This is probably because tissues become less firm with age and this causes veins to stretch more easily. The tendency to develop varicose veins appears to run in families.
You are more likely to develop varicose veins if you are:
- Pregnant. There are number of reasons for this. The change in hormones during this time of life causes all tissues in the body to relax and this also happens in veins. In addition, as the baby increases in size, extra pressure is exerted on the veins in the pelvic region, partially obstructing the flow of blood from the legs. Varicose veins are more likely to appear during the second half of pregnancy
- Number of children. Each pregnancy increases the chance for veins to become damaged
- Above your normal weight. This seems to be more of a factor in women rather than men, although the causes or reasons for this observation are not known
- Chronic constipation. Having a large amount of un-passed stool in your pelvis has the same effect as being pregnant – it causes a partial obstruction to blood flow from the legs and a greater tendency for varicose veins, as well as haemorrhoids
- Urinary retention. This is when you are unable to empty your bladder completely. The most likely cause is an enlarged prostate in men over the age of 50
- Other causes. There are a number of rare causes of varicose veins such as a tumour in your pelvis and previous blood clots in the deep veins of the leg (deep vein thrombosis).
Although factors or causes of varicose veins are well understood, they may appear for no obvious single reason. Varicose veins are more likely to develop if you are on your feet all day, especially if you are standing rather than walking.