The spleen is an organ in the upper far left part of the
abdomen, to the left of the stomach. It varies in size and shape
between people, but is commonly fist-shaped, purple, and about
four inches long. Because the spleen is protected by the rib
cage, you cannot easily feel it unless it is abnormally
enlarged. About 10% of people have a
small extra accessory spleen, which causes no problems and is
considered normal.
The spleen plays
multiple supporting roles in the body. It acts as a filter for
blood as part of the immune system. Old red blood cells are
recycled in the spleen, and platelets and white blood cells are
stored there. It also helps fight certain kinds of bacteria that
cause pneumonia and meningitis.
Bottom line, the spleen filters blood and
helps the body fight infections, but it is not essential for
survival. The spleen can be removed if it is damaged. However,
people without a spleen are more prone to infections.