Merck Manual

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Harry S. Jacob

, MD, DHC, University of Minnesota Medical School

Reviewed/Revised Mar 2023
Topic Resources

Splenomegaly is abnormal enlargement of the spleen.

Splenomegaly is almost always secondary to other disorders. Causes of splenomegaly are myriad, as are the many possible ways of classifying them (see table Common Causes of Splenomegaly Common Causes of Splenomegaly Common Causes of Splenomegaly ). In temperate climates, the most common causes are

In the tropics, the most common causes are

If splenomegaly is massive (spleen palpable 8 cm below the costal margin), the cause is usually

Evaluation of Splenomegaly


Most of the presenting symptoms result from the underlying disorder. However, splenomegaly itself may cause early satiety by encroachment of the enlarged spleen on the stomach. Fullness and left upper quadrant abdominal pain are also possible. Sudden, severe pain suggests splenic infarction. Recurrent infections, symptoms of anemia, or bleeding manifestations suggest cytopenia and possible hypersplenism. In patients who have had blunt abdominal trauma within the last several weeks, splenic enlargement may have resulted from splenic subcapsular hematoma and sudden severe pain and/or shock may indicate splenic rupture.

Physical examination

The sensitivity for detection of ultrasound-documented splenic enlargement is 60 to 70% for palpation and 60 to 80% for percussion. Up to 3% of normal, thin, people have a palpable spleen. Also, a palpable left upper quadrant mass may indicate a problem other than an enlarged spleen such as an enlarged left hepatic lobe due to hepatic vein thrombosis, a hypernephroma, or an adrenal mass.

Other helpful signs include a splenic friction rub and shoulder pain that suggest splenic infarction as well as epigastric or splenic bruits that may occur due to increased blood flow. Adenopathy may suggest a lymphoproliferative, infectious, or autoimmune disorder.



If confirmation of splenomegaly is necessary because the examination is equivocal, ultrasonography is the test of choice because of its accuracy and low cost. CT and MRI may provide more detail of the organ’s consistency. MRI is especially useful in detecting portal or splenic vein thromboses. Nuclear scanning is accurate and can identify accessory splenic tissue often found after splenectomy due to "work hypertrophy" of overlooked splenules or fragments released from a fractured spleen at the time of surgery. Occasionally, multiple spleen remnants can be found throughout the abdomen, often embedded in the neighboring pancreas, a condition called splenosis.

Specific causes suggested clinically should be confirmed by appropriate testing. If no cause is suggested, the highest priority is exclusion of occult infection, because early treatment affects the outcome of infection more than it does most other causes of splenomegaly. Testing should be thorough in areas of high geographic prevalence of infection or if the patient appears to be ill. Complete blood count (CBC), blood cultures, and bone marrow examination (eg, for evidence of cancer or storage diseases) and culture should be considered.

If the patient is not ill, has no symptoms besides those due to splenomegaly, and has no risk factors for infection, the extent of testing is controversial but probably includes CBC, peripheral blood smear, liver tests, and abdominal CT. Flow cytometry and immunochemical assays, such as light chain measurements of peripheral blood and/or bone marrow sections, are indicated if lymphoma is suspected. Lymphoma in the splenic marginal zone, which is uncommon, is often associated with hepatitis C infection Hepatitis C, Chronic Hepatitis C is a common cause of chronic hepatitis. It is often asymptomatic until manifestations of chronic liver disease occur. Diagnosis is confirmed by finding positive anti-HCV and positive... read more (and is important to detect because it can be successfully treated with viral eradication).

Specific peripheral blood findings may suggest underlying disorders (eg, small-cell lymphocytosis in chronic lymphocytic leukemia Chronic Lymphocytic Leukemia (CLL) Chronic lymphocytic leukemia (CLL) is characterized by progressive accumulation of phenotypically mature malignant B lymphocytes. Primary sites of disease include peripheral blood, bone marrow... read more , large granular lymphocytosis in T-cell granular lymphocyte [TGL] hyperplasia or TGL leukemia, atypical lymphocytes in hairy cell leukemia, and leukocytosis and immature forms in other leukemias). Excessive basophils, eosinophils, or nucleated or teardrop RBCs suggest a myeloproliferative neoplasm Overview of Myeloproliferative Neoplasms Myeloproliferative neoplasms are clonal proliferations of bone marrow hematopoietic stem cells, which can manifest as an increased number of functionally normal platelets, red blood cells (RBCs)... read more . Cytopenias suggest hypersplenism Hypersplenism Hypersplenism is cytopenia caused by splenomegaly. (See also Overview of the Spleen.) Hypersplenism is a secondary process that can arise from splenomegaly of almost any cause (see table Common... read more . Spherocytosis suggests hypersplenism or hereditary spherocytosis Hereditary Spherocytosis and Hereditary Elliptocytosis Hereditary spherocytosis and hereditary elliptocytosis are congenital red blood cell (RBC) membrane disorders that can cause a mild hemolytic anemia. Symptoms, generally milder in hereditary... read more Hereditary Spherocytosis and Hereditary Elliptocytosis . Target cells, sickle-shaped cells, or spherocytes can suggest a hemoglobinopathy Overview of Hemoglobinopathies Hemoglobinopathies are genetic disorders affecting the structure or production of the hemoglobin molecule. Hemoglobin molecules consist of polypeptide chains whose chemical structure is genetically... read more .

Some other tests may be useful, even in asymptomatic patients. Serum protein electrophoresis identifying a monoclonal gammopathy or decreased immunoglobulins suggests lymphoproliferative disorders or amyloidosis Amyloidosis Amyloidosis is any of a group of disparate conditions characterized by extracellular deposition of insoluble fibrils composed of misaggregated proteins. These proteins may accumulate locally... read more Amyloidosis ; diffuse hypergammaglobulinemia suggests chronic infection (eg, malaria Malaria Malaria is infection with Plasmodium species. Symptoms and signs include fever (which may be periodic), chills, rigors, sweating, diarrhea, abdominal pain, respiratory distress, confusion... read more Malaria , visceral leishmaniasis Leishmaniasis Leishmaniasis is caused by species of Leishmania. Manifestations include cutaneous, mucosal, and visceral syndromes. Cutaneous leishmaniasis causes painless chronic skin lesions ranging... read more Leishmaniasis , brucellosis Brucellosis Brucellosis is caused by Brucella species, which are gram-negative bacteria. Symptoms begin as an acute febrile illness with few or no localized signs and may progress to a chronic stage... read more , tuberculosis Tuberculosis (TB) Tuberculosis is a chronic, progressive mycobacterial infection, often with an asymptomatic latent period following initial infection. Tuberculosis most commonly affects the lungs. Symptoms include... read more Tuberculosis (TB) ), cirrhosis with congestive splenomegaly, sarcoidosis Sarcoidosis Sarcoidosis is an inflammatory disorder resulting in noncaseating granulomas in one or more organs and tissues; etiology is unknown. The lungs and lymphatic system are most often affected, but... read more Sarcoidosis , or connective tissue disorders (eg, systemic lupus erythematosus, Felty syndrome in patients with rheumatoid arthritis) . Flow cytometry can identify a small monoclonal lymphocyte population suggestive of lymphoma. Elevation of serum uric acid suggests a myeloproliferative or lymphoproliferative disorder. Elevation of leukocyte alkaline phosphatase (LAP) suggests a myeloproliferative neoplasm, whereas decreased levels suggest chronic myelocytic leukemia.

If testing reveals no abnormalities other than splenomegaly, the patient should be reevaluated at intervals of 6 to 12 months or when new symptoms develop.

Treatment of Splenomegaly

  • Treatment of underlying disorder

Treatment is directed at the underlying disorder. An enlarged spleen itself in an asymptomatic patient needs no treatment unless severe hypersplenism Hypersplenism Hypersplenism is cytopenia caused by splenomegaly. (See also Overview of the Spleen.) Hypersplenism is a secondary process that can arise from splenomegaly of almost any cause (see table Common... read more or early satiety due to encroachment on the stomach is present. Patients with palpable or very large spleens probably should avoid contact sports and weight-lifting to decrease the risk of splenic rupture.

Key Points

  • Splenomegaly is almost always secondary to other disorders.

  • When testing for etiology of splenomegaly and no cause is immediately apparent, infectious causes are important to exclude.

  • Asymptomatic patients with an enlarged spleen do not require treatment but should avoid contact sports and weight-lifting to decrease the risk of splenic rupture.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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