What causes thread veins?
Profuse thread veins at the inner nakle due to underlying venous reflux
There are two things that should be considered when thinking about “causes” of thread veins of the legs.
The first is the skin type itself, and the second is whether the thread veins are associated with any underlying condition
Considering the skin type, thread veins of the legs can found in all skin types and colours – from the very whitest skin to the very darkest skin. However there does seem to be a family link that probably has some genetic basis that seems to make thread veins of the legs more common in some families than others.
In patients who develop leg thread veins with no underlying cause, it is often just a process of time, with more appearing the older one gets. In such patients, successful treatment of the thread veins does not prevent others from appearing.
Although humans always look for a cause of any condition that they can understand, there are many things that patients blame incorrectly for their thread veins of the legs which simply are not the problem. A great many women will erroneously blame the fact that they cross their legs when sitting down, have hot baths or saunas, or wear tight clothes such as boots or hold-up stockings. None of these cause thread veins of the legs and indeed, when someone points out the thread vein cluster “caused” by one of these or other similar events, one can usually find other thread veins elsewhere on the legs that are not affected by the condition that is blamed, and can find normal skin without thread veins that has the same event affecting it.
However thread veins of the legs can be caused by severe trauma to the legs such as a “crush injury”. If the patient has had a severe accident such as road traffic accident, and part of the leg was crushed and severely damaged, it is not uncommon to find thread veins in the area. Also, although varicose vein surgery is often blamed for the formation of thread veins of the legs, when photographs are taken before and after the event, we can see that formation of leg thread veins following varicose vein surgery is rare. However on occasion, thread veins can be seen appearing through wounds, particularly if the old stripping type of operation is performed. Therefore everyone undergoing any varicose vein surgery must be aware that they may need treatment of thread veins to follow to get the best cosmetic result.
The second “cause” of leg thread veins – which is far more common than above – is when the thread veins are associated with an underlying condition. In almost all of these cases, the underlying condition is incompetence of the superficial veins (i.e. superficial veins in which the valves not working) which allows venous reflux (blood to flow the wrong way down the veins) which is also called “hidden varicose veins“.
In these situations, it is not known whether the thread veins are actually caused by the underlying venous reflux (“hidden varicose veins“) or whether pre-existing thread veins on the surface merely link up at a later time with the underlying incompetent superficial veins (“hidden varicose veins“). Whichever the sequence of events, successful treatment of these leg thread veins depends upon the identification of the superficial venous reflux (“hidden varicose veins“) and successful treatment before treatment of the leg thread veins themselves.
Rarely, thread veins of the legs are associated with more serious underlying problems such as “post-phlebitic limb” or venous abnormalities such as Klippel Trelawney syndrome.