Sclerotherapy is a procedure that treats blood vessels or blood vessel malformations (vascular malformations) as well as those of the lymphatic system.

The surgeon injects a chemical into the veins. The chemical irritates and scars your veins from the inside out so your abnormal veins can then no longer fill with blood. Blood that would normally return to the heart through these veins returns to the heart through other veins. The body eventually absorbs the veins that received the injection.