Section 14. Blood Disorders

Chapter 179. Spleen Disorders

Topics: Introduction | Enlarged Spleen | Ruptured Spleen

Enlarged Spleen

An enlarged spleen (splenomegaly) is not a disease in itself but the result of an underlying disorder. Many disorders can make the spleen enlarge. To pinpoint the cause, a doctor must consider disorders ranging from chronic infections to blood cancers.

When the spleen enlarges, it traps and stores an excessive number of blood cells and platelets (hypersplenism), thereby reducing the number of blood cells and platelets in the bloodstream. This process creates a vicious circle: the more cells and platelets the spleen traps, the larger it grows; the larger it grows, the more cells and platelets it traps. Eventually, the greatly enlarged spleen also traps normal red blood cells, destroying them along with the abnormal ones. In addition, excessive numbers of blood cells and platelets can clog the spleen, interfering with its functioning.

An enlarged spleen may outgrow its own blood supply. When parts of the spleen do not get enough blood, they may become damaged, causing them to bleed or die.

See the sidebar Causes of an Enlarged Spleen.

Symptoms

An enlarged spleen does not cause many symptoms, and the symptoms that it does cause may be mistaken for many other medical conditions. Because the enlarged spleen lies next to the stomach and sometimes presses against it, a person may feel full after eating a small snack or even without eating. A person may also have abdominal or back pain in the area of the spleen; the pain may spread to the left shoulder, especially if parts of the spleen do not get enough blood and start to die.

When the spleen removes too many blood cells and platelets from the bloodstream, a variety of problems may develop. These problems include anemia as a result of too few red blood cells, frequent infections as a result of too few white blood cells, and the tendency to bleed as a result of too few platelets.

Diagnosis

A doctor may suspect that the spleen is enlarged when the person complains of fullness or pain in the upper left portion of the abdomen or back. Usually, the doctor can feel an enlarged spleen during a physical examination. An x-ray of the abdomen may also show that the spleen is enlarged. In some cases, an ultrasound or computed tomography (CT) scan is needed to determine how large the spleen is and whether it is pressing on other organs. A magnetic resonance imaging (MRI) scan provides similar information and also traces blood flow through the spleen. Other specialized scanning devices use mildly radioactive particles to assess the spleen's size and function and to determine whether it is accumulating or destroying large numbers of blood cells.

Blood tests show decreased numbers of red blood cells, white blood cells, and platelets. When blood cells are examined under a microscope, their shape and size may provide clues to the cause of the spleen enlargement. An examination of bone marrow (see Section 14, Chapter 170) may show cancer of the blood cells (such as leukemia or lymphoma) or an accumulation of unwanted substances (such as occurs in storage diseases (see Section 23, Chapter 282)). Blood protein measurement can determine whether other conditions are present that can cause the spleen to enlarge, such as amyloidosis, sarcoidosis, malaria, kala-azar, brucellosis, and tuberculosis. Liver function tests help determine whether the liver is also diseased.

Doctors cannot easily remove a sample of the spleen for examination because inserting a needle or cutting spleen tissue may cause uncontrollable bleeding. If a person's enlarged spleen is removed during surgery to diagnose or treat certain diseases, the spleen is sent to a laboratory, where the cause of enlargement can usually be determined.

Treatment

When possible, a doctor treats the underlying disease that caused the enlarged spleen. Surgical removal of the spleen (splenectomy) may be necessary but can cause problems, including an increased susceptibility to infections. However, the risks are worth taking in certain critical situations: when the spleen destroys red blood cells so rapidly that severe anemia develops; when it so depletes stores of white blood cells and platelets that infection and bleeding are likely; when it is so large that it causes pain or puts pressure on other organs; or when it is so large that parts of it bleed or die. As an alternative to surgery, radiation therapy can sometimes be used to shrink the spleen.