The spleen sits under your rib cage in the upper left part of your abdomen toward your back. It is an organ that is part of the lymph system and works as a drainage network that defends your body against infection.
The spleen is a delicate, fist-sized organ under your left rib cage near your stomach. It contains special white blood cells that destroy bacteria and help your body fight infections. The spleen also makes red blood cells and helps remove, or filter, old ones from the body's circulation.
A layer of tissue entirely covers the spleen in a capsule-like fashion, except where veins and arteries enter the organ. This tissue, called the splenic capsule, helps protect the spleen from direct injury.
White blood cells produced in the spleen engulf bacteria, dead tissue, and foreign matter, removing them from the blood as blood passes through it. The spleen also maintains healthy red and white blood cells and platelets; platelets help your blood clot. The spleen filters blood, removing abnormal blood cells from the bloodstream.
A spleen is normally about the size of your fist. A doctor usually can't feel it during an exam. But diseases can cause it to swell and become many times its normal size. Because the spleen is involved in many functions, many conditions may affect it.
An enlarged spleen is not always a sign of a problem. When a spleen becomes enlarged, though, it often means it has been doing its job but has become overactive. For example, sometimes the spleen is overactive in removing and destroying blood cells. This is called hypersplenism. It can happen for many reasons, including problems with too many platelets and other disorders of the blood.
Causes of an Enlarged Spleen
An enlarged spleen can be caused by infections, cirrhosis and other liver diseases, blood diseases characterized by abnormal blood cells, problems with the lymph system, or other conditions.
Here are some common causes of an enlarged spleen: