I get scelotherapy on my legs 3 times a year for 25 years now. can this prevent or promote thrombosis?

? decreased risk: The real answer is that no one really knows. Your risk of thrombosis was probably quite low in the first place, or else you would have had a clot by now. By having frequent sclerotherapy sessions for such a long time, it has likely prevented you from developing large varicose veins which carry a higher risk of thrombosis associated with them. Bottom line, i don't think you need to worry.

Probably not: I assume that you are having small 'thread veins" or telangiectasias treated. Depending on the sclerosant used, there may be a very low risk of DVT as a complication of sclerotherapy. If you wear compression hose after sclerotherapy the hose decreases your risk of dvt.

Promote: Sclerotherapy promotes thrombosis of the veins by damaging the endothelial cells with the sclerotherapy agent.