What is the spleen?

The spleen is an organ on the left side of the abdomen.  Normally you can't feel your spleen.  In certain diseases, the spleen becomes enlarged and can be felt descending below the ribcage on the left side of the body.  The spleen's primary role is to serve as a filter for the blood.  Special white blood cells sift the blood as it flows through the spleen to pull out particles and microbes, protecting us from infection.  Those cells then turn on the immune response when danger is detected.  Sometimes the spleen has to be removed because it can accidentally trigger an immune response to the body itself (so-called autoimmune response), and sometimes it has to be removed because someone has had severe trauma, like a car accident.  You can live fairly normally without a spleen, but your risk of infection becomes higher, and if infected, the infection can be more life-threatening without a spleen.

The spleen is an organ in the upper left side of the abdomen that filters the blood by removing old or damaged blood cells and platelets and helps the immune system by destroying bacteria and other foreign substances. It also holds extra blood that can be released into the circulatory system, if needed.

The spleen is a useful but nonessential organ. It is sometimes removed (splenectomy) in people who have blood disorders, such as thalassemia or hemolytic anemia. If the spleen is removed, a person must get certain immunizations to help prevent infections that the spleen normally fights.

The spleen is an organ in the body’s defense system. The spleen stores red blood cells, destroys old red blood cells, and produces antibodies and lymphocytes to fight against infections and diseases. (This answer provided for NATA by the University of Montana Athletic Training Education Program.)