Last updated: 11/24/2009

The human spleen is a dark purple bean-shaped organ located in the upper left side of the abdomen just behind the bottom of the rib cage. In adults, the spleen is about 4.8 X 2.8 X 1.6 in (12 X 7 X 4 cm) in size, and weighs about 4–5 oz (113–14...

g). The spleen plays a role in the immune system of the body. It also filters foreign substances from the blood and removes worn-out blood cells. The spleen regulates blood flow to the liver and sometimes stores blood cells—a function known as sequestration. In healthy adults, about 30% of blood platelets are sequestered in the spleen.

Splenectomies are performed for a variety of different reasons and with different degrees of urgency. Most splenectomies are done after a patient has been diagnosed with hypersplenism. Hypersplenism is not a specific disease but a syndrome (group or cluster of symptoms) that may be associated with different disorders. Hypersplenism is characterized by enlargement of the spleen (splenomegaly), defects in the blood cells, and an abnormally high turnover of blood cells. It is almost always associated with such specific disorders as cirrhosis of the liver or certain cancers. The decision to perform a splenectomy depends on the severity and prognosis of the disease that is causing the hypersplenism.

Splenectomy always required

There are two diseases for which a splenectomy is the only treatment—primary cancers of the spleen and a blood disorder called hereditary spherocytosis (HS). In HS, the absence of a specific protein in the red blood cell membrane leads to the formation of relatively fragile cells that are easily damaged when they pass through the spleen. The cell destruction does not occur elsewhere in the body and ends when the spleen is removed. HS can appear at any age, even in newborns, although doctors prefer to put off removing the spleen until the child is five to six years old.

Splenectomy usually required

There are some disorders for which a splenectomy is usually recommended. They include:

• Immune (idiopathic) thrombocytopenic purpura (ITP). ITP is a disease in which platelets are destroyed by antibodies in the body's immune system. A splenectomy is the definitive treatment for this disease and is effective in about 70% of cases of chronic ITP.
• Trauma. The spleen can be ruptured by blunt as well as penetrating injuries to the chest or abdomen. Car accidents are the most common cause of blunt traumatic injury to the spleen.
• Abscesses. Abscesses of the spleen are relatively uncommon but have a high mortality rate.
• Rupture of the splenic artery. This artery sometimes ruptures as a complication of pregnancy.
• Hereditary elliptocytosis. This is a relatively rare disorder. It is similar to HS in that it is characterized by red blood cells with defective membranes that are destroyed by the spleen.

Splenectomy sometimes required

Other disorders may or may not necessitate a splenectomy. These include:

• Hodgkin's disease, a serious form of cancer that causes the lymph nodes to enlarge. A splenectomy is often performed in order to find out how far the disease has progressed.
• Autoimmune hemolytic disorders. These disorders may appear in patients of any age but are most common in adults over 50. The red blood cells are destroyed by antibodies produced by the patient's own body (autoantibodies).
• Myelofibrosis. Myelofibrosis is a disorder in which bone marrow is replaced by fibrous tissue. It produces severe and painful splenomegaly. A splenectomy does not cure myelofibrosis but may be performed to relieve pain caused by the swelling of the spleen.
• Thalassemia. Thalassemia is a hereditary form of anemia that is most common in people of Mediterranean origin. A splenectomy is sometimes performed if the patient's spleen has become painfully enlarged.