Spleen is an organ located in the left upper abdomen. It has a rich blood supply and performs many functions. Spleen is used to break down old and faulty red blood cells, it functions as a reservoir of blood, contributes to immune system reactions an the development of white blood cells and in certain phases of human development spleen even serves as a place of formation of hematopoiesis. In normal conditions the spleen is hidden below the left costal arch, where it is protected and impalpable. Under certain circumstances, however, spleen enlarges. This can be related to unpleasant pressure and abdominal pain located in the upper left abdominal quadrant. Enlargement of the spleen is technically referred to as splenomegaly.
Enlarged spleen is characteristic for infectious mononucleosis and also for malaria, where the red blood cells are damaged by a tropical parasite known as plasmodium. However, spleen enlargement may be present by virtually all septic conditions. This is due to the increased uptake and destruction of microorganisms in the spleen. Bacterial sepsis can even result in spleen abscess formation.
Spleen enlarges when it is overfilled with blood. The most common and clinically harmless congestion occurs during exercise in untrained individuals, typically when running. Pressure and pain under the left costal arch quickly disappears at rest. There are, of course, more severe causes of spleen blood congestion including situation when blood can not be properly drained by venous system. Such conditions include liver cirrhosis and other diseases related to portal hypertension.
Spleen is a relatively well-protected organ because of its fragility and rich blood supply. However, spleen may be injured during bigger accidents, typically car crashes. Spleen injuries are often insidious as even ruptured spleen may for a certain time bleed under spleen capsule without any serious symptom. Spleen enlarges by blood accumulated within the capsule and when this ruptures, the person may suddenly exsanguinate into abdominal cavity.
These “blood tumors” may cause spleen enlargement. This is due to proliferation of tumor cell in spleen tissue. Spleen may be also affected in lymphomas.
Diseases with excessive break-down of red blood cells
Virtually any disease of red blood cells, which shortens their lifespan and increases decay, also causes spleen enlargement. This is due to fact that spleen is an important place of erythrocytes breakdown. These diseases include sickle-cell disease, thalassemia and autoimmune hemolytic anemia.
This group of diseases is related to accumulation of certain substances in the body that stores in various organs and tissues. Usually these are congenital and their cause is mainly a defective enzyme. There exist, however, even some acquired storage diseases like amyloidosis that is caused by accumulation of protein known as amyloid.
Diagnosis is based on physical examination (spleen palpation). Abdominal ultrasound is more precise as it not only confirms the enlargement but it helps us to measure the size of enlarged spleen. Ultrasound is also appropriate examination to detect various local abnormalities including spleen hemangiomas, abscesses and hemorrhage (in spleen injury).
Blood tests are done mainly to exclude blood disorders with possible relation to spleen such as anemia, leukemic changes, etc. Further examination depends on outcome of previously mentioned diagnostic methods. When there is a suspicion of a blood disorder, it is advisable to perform a hematologic examination.