Sclerotherapy with Polidocanol can be very safe and effective as long as the cause of the varicose veins is close to the veins that are being injected.
Varicose veins are dilated veins and are the result of abnormally high pressure in the veins. This, in turn, is due to the combination of weak vein walls and broken vein valves.
Typically, surface spider veins are driven by reticular veins just under the skin. These reticular veins may be driven by subcutaneous veins, which may themselves be driven by high pressure in the larger greater saphenous vein or in perforating veins. Perforators connect the surface veins with the major deep veins of the legs.
The more central or the larger the driving veins are, the less likely sclerotherapy will be successful. As a rule, if the varicose veins cause aching or pain in the legs, the veins are so dilated that sclerotherapy with any agent will probably not work, and the patient may need surgery. If the varicose veins are associated with swelling of the leg or other signs of chronic deep venous insufficiency even surgery may not help because the ultimate drivers are the large, deep veins of the leg.
One of the reasons Polidocanol is so safe is that, when given in the proper concentration, it becomes ineffective (too dilute) in larger veins. That means that when it gets to those more central veins it does not damage or destroy them, but it leaves them in tact and still under high pressure - able to continue driving the varicosities.
Although Polidocanol is not yet FDA approved, it is still the gold standard of safe and effective sclerotheraputic agents.
The key to successful sclerotherapy is an understanding of the cause of the varicose veins. If the driving high pressure is close to the veins being treated it will probably work, and Polidocanol is a good agent to use. If the high pressure driver is too deep or central the chance of success is markedly reduced no matter what the sclerotheraputic agent. An agent that will effectively damage an offending central vein is not safe.
This is a complex subject.
