The spleen is an organ located in the upper left quadrant of the abdomen just below the diaphragm and protected under the lower left ribs.
The spleen has a couple of important functions involving blood cells within the body.
- It filters blood and removes old and damaged red blood cells, bacteria, and other particles as they pass through the maze of blood vessels within the spleen.
- It produces lymphocytes, a type of white blood cell that produces antibodies and assists immune system.
The filtration system is part of the red pulp while the white pulp of the spleen contains the immune functioning cells. Normally, the spleen is a small organ about the size of a small fist or orange. Splenomegaly describes the situation where the spleen enlarges in size (spleen+megaly=enlargement).
What are the causes of an enlarged spleen?
The spleen enlarges if it is asked to do excessive work in filtering or manufacturing blood cells, if there is abnormal blood flow to it, or if it is invaded with abnormal cells or deposits.
1. Abnormal red blood cells: Since the spleen filters abnormal blood cells and removes them from the circulatory system, diseases that result in abnormal red cells will cause the spleen to enlarge.Sickle cell disease, thalassemia, and spherocytosis are examples of diseases that form unusually shaped cells that cannot easily maneuver through the small blood vessels and capillaries of the body. If they are not removed by the spleen, these abnormal cells can cause blood clots and decrease circulation. However, removing them causes the spleen to swell and enlarge.
2. Viral and bacterial infection: The spleen is involved in making cells that fight infection and part of that response is to enlarge. This is commonly seen in viral infections such as infectious mononucleosis (caused by the Epstein Barr virus), AIDS and viral hepatitis. Examples of bacterial infections associated with splenomegaly include tuberculosis, malaria, and anaplasmosis (formerly known as ehrlichiosis).
Splenic vein pressure/blockage: Blood enters the spleen through the splenic artery and leaves through the splenic vein. If the pressure within the vein increases or if the splenic vein becomes blocked, blood cannot leave the spleen and it may swell. Because of the relationship to liver blood flow, cirrhosis and portal vein obstruction can cause complications with venous blood flow from the spleen. Congestive heart failure may cause both the liver and spleen to swell because of increased venous pressure.
3. Cancers: Leukemias and both Hodgkins and non-Hodgkin lymphomas can cause the spleen to enlarge, as can a variety of other tumors including melanoma.
4. Metabolic disease: Metabolic diseases that enlarge the spleen include Niemann-Pick disease, Gaucher’s disease, and Hurler Syndrome.
What are the symptoms of an enlarged spleen?
An enlarged spleen itself usually causes no symptoms; the symptoms of an underlying disease are often the reason a patient might seek care. These may include weakness and fatigue from anemia, easy bleeding from decreased platelets in the bloodstream, or recurrent infections from poor white blood cell function.
However, as the spleen enlarges, it can press up against the diaphragm, the muscle that separates the chest and abdominal spaces. Diaphragm irritation may refer pain to the left shoulder. An enlarged spleen also can push toward the stomach and cause anorexia or a loss of appetite and a sense of early fullness when eating.
Since the enlarged spleen grows beyond the protection of the ribcage it becomes more likely to be injured, thereby increasing the chance that abdominal pain may occur.
Depending upon the amount of spleen damage after injury, there can be bleeding into the abdomen with associated distention (bloating), pain to the back and shoulder, and signs and symptoms of shock. These can include weakness, shortness of breath, and cool, clammy and sweaty skin.
When should I seek medical care for an enlarged spleen?
Most often, the diagnosis of an enlarged spleen is made incidentally by the care provider. There are usually no symptoms that would bring a patient to see a doctor. However, unexplained symptoms like those mentioned above should be investigated by a care provider.
How is an enlarged spleen diagnosed?
Most often an enlarged spleen is found incidentally on physical examination by the health care practitioner. The spleen usually is small enough to hide underneath the left rib cage in the upper abdomen. The enlarged spleen tip can be felt in the left upper quadrant of the abdomen and as it continues to enlarge the tip moves towards the right lower quadrant. In some thin people, the spleen can be felt in the abdomen but is normal in size. An enlarged spleen measures about 12 to 20 cm (4.5 to 8 inches) in any dimension while a spleen greater than 20 cm (8 inches) is considered severe enlargement.
If there is concern that the spleen is enlarged, blood tests may be considered to assess the cause of the enlargement. Common tests may include a complete blood count (CBC) looking for abnormal red or white blood cells, a peripheral smear to assess at the types and shapes of blood cells or a monospot, if the diagnosis of infectious mononucleosis is being considered. Other tests evaluating liver or heart function may be considered if clinically indicated.
An abdominal ultrasound, CT, or MRI of the abdomen may be used to evaluate the size of the spleen and to look for other abnormalities in the abdominal cavity that may be associated with splenomegaly.
What is the treatment for an enlarged spleen?
Treatment for an enlarged spleen is usually directed at the underlying medical condition that resulted in the splenomegaly. Depending on the underlying problem, treatments can be with antibiotics, chemotherapy, or radiation. These treatments are for the underlying disease and may allow the spleen to reduce in size; however, in some cases, the spleen will remain enlarged.
On occasion, the spleen may need to be removed surgically (splenectomy = spleen + ectomy=removal) as part of the disease treatment. For example, in hereditary spherocytosis, removing the spleen prevents the anemia that occurs when the abnormally shaped red blood cells are continually being filtered out and removed from the blood stream.
What are the complications of an enlarged spleen?
When the spleen enlarges, it loses some of the protective covering of the lower rib cage and becomes more vulnerable to injury. The enlarged spleen is fragile and can be damaged with relatively minor blows to the upper abdomen. It is a relatively solid organ and can fracture or crack causing significant and potentially life-threatening bleeding.
The enlarged spleen can also trap an excessive number of blood cells within it causing:
- anemia (decreased numbers of red blood cells), which may lead to weakness, shortness of breath, and easy fatigue;
- leukopenia (decreased white blood cells), which may lead to increased risk of infection; and
- thrombocytopenia (decreased platelets), which may lead to infection or to bleeding problems.
If the spleen needs to be removed, there is an increased risk of infection, especially due to bacteria such as pneumococcus (Streptococcus pneumoniae), Hemophilus influenza, and meningococcus (Neisseria meningitides). It is important to consider keeping immunizations (particularly the pneumococcal vaccine, since about 50% to 90% of post splenectomy infections are due to encapsulated streptococci) current against these infections in patients whose spleen has been removed.
Can an enlarged spleen be prevented?
Splenomegaly is a complication of an underlying disease or illness and in itself cannot be prevented. Ideally, early recognition of an enlarged spleen may help the health care practitioner come to an early diagnosis as to the cause and perhaps prevent further spleen enlargement.
What is the outlook (prognosis) for an enlarged spleen?
Depending upon the cause, the enlarged spleen may return to normal size and function when the underlying disease is treated or resolved.
- Commonly, in infectious mononucleosis, the spleen returns to normal as the infection gets better.
- In some circumstances, removing the spleen is part of the treatment and can make the person much more susceptible to infections.
- Many illnesses and diseases result with the enlarged spleen as a permanent physical finding and may result in only a fair prognosis because the person may be more prone to splenic injury, infections, and abnormal bleeding.
Enlarged Spleen At A Glance
- The spleen is responsible for filtering the blood and removing aged and damaged cells. It is also a key part of the immune and lymph system of the body.
- An enlarged spleen is not normal and usually is a physical finding of an underlying disease or illness.
- Blood tests may be used to help make the diagnosis of underlying diseases that are associated with splenomegaly.
- Ultrasound, CT, and MRI can help measure the size of the spleen and also look for associated abnormalities in the abdominal cavity.
- The treatment for an enlarged spleen is directed to the underlying illness. Splenectomy (removal of the spleen) may be part of that treatment.
