Unlike your venous system, your lymphatic system has no pumping mechanism to keep the fluid circulating through the body. Therefore, the lymphatic system is always at a higher risk of blockage.  
The lymphatic system, (lymph, lymph nodes and lymph vessels) supports the circulatory system by draining excess fluids and proteins from tissues back into the bloodstream, thereby preventing tissue swelling. It serves as a defense system for the body, filtering out organisms that cause diseases, producing white blood cells, and generating antibodies which keeps the body well.