Q1 “Crossing your legs causes varicose veins”
Q2 “Pregnancy causes varicose veins”
Q3 “Standing for long periods of time causes varicose veins”
Research by Mark Whiteley from the 1990s has shown that teenagers who are susceptible to varicose veins, lose the valves in their veins as they get older. By the age of 18, one in nine 18-year-olds were found to have lost their valves and therefore have “hidden varicose veins” (venous reflux disease or venous incompetence). This meant that as they stand, blood that should be pumped back to the heart actually falls backwards down these veins, causing damage to the vein walls further down the leg, stretching the vein walls and causing varicose veins.
When people are still young and the process has only just started, the veins are strong enough to withstand this constant battering. Therefore we call this state “hidden varicose veins” as nothing can be seen on the surface, but duplex ultrasound shows us that the valves are not working and blood is refluxing the wrong way down the veins on standing. Without duplex ultrasound or another other medical test, it is impossible for anyone looking at the leg to know that are hidden varicose veins within it.
When children grow up and go to work, many of those who have hidden varicose veins will slowly start to develop visible varicose veins. The speed at which these become visible will depend upon several factors. Some will never become visible because the veins are too deep. These are the veins that will go on to cause venous eczema, skin discolouration at the ankles and leg ulcers in later life.
Those that have tributary veins closer to the surface of the skin will start to see these as varicose veins if these veins continue to dilate. Things that will cause this dilation to occur include; how many valves have been lost in the underlying veins, which veins are affected, the diameter of the veins, the strength of the vein walls and how often blood is allowed to reflux down the veins, hitting the walls of these veins and causing them to dilate.
In people who stand a lot at work, the heart is much higher than the ankles compared to someone who is sitting at work. Therefore the column of blood from heart to ankles which causes pressure on the vein walls is higher when standing, if there are no valves in the vein to interrupt this column of blood. Therefore when a person who has got hidden varicose veins stands up, a surge of blood falls down the veins, hitting the walls of these veins under the skin and starting to stretch them. The longer someone is on their feet, the more often this happens and therefore the quicker these veins are likely to dilate.
Therefore it is not standing for long periods of time that causes varicose veins. Rather if someone has already lost their valves due to their genetic make-up, then they are more likely to see varicose veins early and to develop worse varicose veins quicker if they have a job that makes them stand for long periods of time.
However people who have valves that work in their veins and who work in jobs where they have to stand for long periods of time, do not go on to get varicose veins unless the valves fail.
Simply, standing for long periods of time does not cause varicose veins, but if you already have “hidden varicose veins” then standing for long periods of time will make your varicose veins deteriorate quicker.
Q4 “Being overweight causes varicose veins”
In the past it has been thought that increased pressure in the abdomen from excess fat would “push” on the veins in the pelvis, increasing the pressure in the leg veins and therefore causing varicose veins.
However excess pressure on the pelvic veins does not cause extra pressure being transmitted down the blood into leg veins. Rather it pushes on the vein wall trying to close the veins. If the veins did close, the blood would clot and a deep-vein thrombosis (DVT) would be caused.
Therefore excess weight does not cause increased pressure in the veins and there is no link between weight and the development of varicose veins.
Q5 “Being constipated and straining on the toilet causes varicose veins”
Q6 “Hot baths cause varicose veins”
In this case, we know that heat causes veins to dilate. We also know that varicose veins are dilated veins. Therefore it would seem logical that the two must be linked.
Of course this is not the case.
When veins dilate due to heat, this is a normal physiological reaction of normal veins in the skin that are concerned with temperature control. Varicose veins however, are pathologically dilated veins, deeper under the skin than the veins involved in temperature control, which dilate because of venous reflux during standing and walking.
Another very simple and obvious argument is: – if hot baths really did cause varicose veins, why is it that people often get varicose veins only on one leg and not the other? And why is it that when we scan patients, it is often only one vein that has lost its valves and become varicose, rather than all of the veins in the leg?
If varicose veins were really caused by having hot baths, then we should see veins affected in both legs in all people, and all of the veins in the legs should be affected. Similarly, if heat is a cause of varicose veins, we really should be seeing large numbers of varicose veins in populations living in hot climates and far fewer in people living in colder climates.
However it is remarkable that when population studies are performed and results are corrected for the age of the population, the number of people with varicose veins and “hidden varicose veins” (venous reflux or venous incompetence) is very similar in similar populations in different countries with vastly different temperatures.
Therefore hot baths and indeed hot weather do cause normal veins to dilate which will shrink again in the cold, but these factors do not cause varicose veins.