Splenomegaly (Enlarged Spleen)

How the spleen enlarges

The spleen filters blood, removes old or damaged red cells, stores platelets and white cells, and mounts immune responses to blood-borne germs. It enlarges through six main mechanisms:

Massive splenomegaly

When the spleen extends to the pelvis or across the midline, the list of causes narrows to chronic myeloid leukemia, myelofibrosis, some lymphomas, hairy cell leukemia, Gaucher disease, chronic malaria (hyperreactive malarial splenomegaly) and visceral leishmaniasis.

Hypersplenism

An enlarged spleen can trap and destroy too many blood cells, causing low platelets, low white cells, anemia, or all three. This is hypersplenism. Platelet counts often fall first: about a third of platelets normally sit in the spleen, and a large spleen can hold far more. Bleeding is usually mild, but infections and anemia can be significant.

Symptoms

Symptoms are often absent or mild: left upper fullness, early satiety, left shoulder discomfort, and symptoms of low blood counts such as tiredness, bruising and infections. Symptoms of the underlying condition usually dominate. For a symptom-first guide to what an enlarged spleen feels like and when to worry, see enlarged spleen symptoms.

Diagnosis

Examination

A doctor feels for the spleen tip below the left ribs while you breathe in, and taps over the lower left chest wall. A normal spleen is rarely felt, but examination misses many mildly enlarged spleens.

Imaging

• Ultrasound: the first test. Measures length (enlarged is commonly defined as over 13 cm in adults, though normal size varies with height), checks the liver, portal vein flow and focal lesions.
• CT or MRI: for lymph node assessment, focal lesions or when ultrasound is inconclusive.

Blood tests

• full blood count and blood film (looking for abnormal cells, hemolysis or parasites)
• reticulocyte count, bilirubin, LDH and haptoglobin for hemolysis
• liver function and clotting tests
• tests for mononucleosis, CMV, HIV, hepatitis B and C, and malaria if relevant
• autoimmune markers and inflammatory markers
• genetic tests such as JAK2 and BCR-ABL for myeloproliferative neoplasms

Further tests

Bone marrow biopsy for suspected blood cancer or marrow fibrosis, lymph node biopsy for lymphoma, liver elastography or biopsy for liver disease, and endoscopy for varices in portal hypertension.

Treatment

Treatment targets the cause:

• Infections: most viral causes resolve on their own; bacterial and parasitic infections are treated specifically.
• Liver disease: treating hepatitis, stopping alcohol, managing portal hypertension and screening for varices.
• Blood cancers: chemotherapy, targeted drugs (for example tyrosine kinase inhibitors in CML, JAK inhibitors in myelofibrosis, which also shrink the spleen).
• Hemolytic anemias: folic acid, transfusions, immunosuppression for autoimmune types.
• Storage diseases: enzyme replacement therapy for Gaucher disease.

Splenectomy

Removing the spleen, usually by keyhole surgery, is considered for:

• rupture or major injury that cannot be managed otherwise
• hereditary spherocytosis and some other hemolytic anemias
• immune thrombocytopenia not responding to medicines
• massive, painful splenomegaly or severe hypersplenism
• diagnosis when no other test is conclusive

Partial splenic embolization, blocking part of the spleen's blood supply, is an alternative in some people.

Living without a spleen

People without a working spleen are at lifelong risk of overwhelming infection, especially from pneumococcus, meningococcus and Haemophilus influenzae type b. Protection includes:

• vaccines against these bacteria, ideally at least 2 weeks before planned surgery, plus yearly flu vaccine
• daily preventive antibiotics in some people, especially children and in the first years after surgery
• an emergency supply of antibiotics and immediate medical care for any fever
• a medical alert card or bracelet
• malaria prevention when traveling

Complications

• Splenic rupture, spontaneously or after minor trauma
• Splenic infarction (part of the spleen loses blood supply), causing sudden left-sided pain
• Hypersplenism with low blood counts
• Complications of the underlying disease

Outlook

The outlook depends on the cause. Infection-related enlargement usually resolves fully within weeks to months. Splenomegaly from cirrhosis or chronic blood disorders tends to persist and is managed long term. Many blood cancers that cause splenomegaly are now controlled for years with modern treatment.

Frequently asked questions

What is the most common cause of splenomegaly?

In the US and Europe, the most common causes are liver disease with portal hypertension, blood cancers such as lymphoma and leukemia, and infections such as mononucleosis. Worldwide, malaria and other tropical infections are major causes.

What size spleen is considered enlarged?

A normal adult spleen is up to about 11 to 13 cm long on ultrasound. Lengths above about 13 cm are generally considered enlarged, and spleens above about 20 cm or reaching the pelvis are called massive. Normal size varies with height and sex.

What is hypersplenism?

Hypersplenism is when an enlarged spleen traps and destroys too many blood cells, lowering platelets, white cells or red cells. It can cause bruising, infections and anemia. Treating the cause, and occasionally removing or partly blocking the spleen, improves the counts.

Is splenomegaly serious?

It can be, depending on the cause. Mild enlargement from a viral infection is usually harmless and temporary. Splenomegaly from liver cirrhosis or blood cancers reflects a serious underlying illness. Any unexplained enlarged spleen should be fully investigated.

Can you live without a spleen?

Yes. Other organs take over most of its functions. The main risk is serious bacterial infection, so people without a spleen need specific vaccines, sometimes daily antibiotics, and urgent medical care for any fever.