Your spleen is an organ located just below your left rib cage. Many conditions — including infections, liver disease and some cancers — can cause an enlarged spleen, also known as splenomegaly (spleh-no-MEG-uh-lee).
An enlarged spleen usually doesn't cause symptoms. It's often discovered during a routine physical exam. Your doctor generally can't feel a normal-sized spleen in adults but can feel an enlarged spleen. Your doctor will likely request imaging and blood tests to help identify the cause.
Treatment for an enlarged spleen focuses on the underlying condition that's causing it. Surgically removing an enlarged spleen isn't usually the first treatment, but is sometimes recommended.
An enlarged spleen may cause:
No symptoms in some cases
Pain or fullness in the left upper abdomen that may spread to the left shoulder
Feeling full without eating or after eating only a small amount from the enlarged spleen pressing on your stomach
When to see a doctor
See your doctor promptly if you have pain in your left upper abdomen, especially if it's severe or the pain gets worse when you take a deep breath.
A number of infections and diseases may cause an enlarged spleen. The enlargement of the spleen may be temporary, depending on treatment. Contributing factors include:
Viral infections, such as mononucleosis
Bacterial infections, such as syphilis or an infection of your heart's inner lining (endocarditis)
Parasitic infections, such as malaria
Cirrhosis and other diseases affecting the liver
Various types of hemolytic anemia — a condition characterized by early destruction of red blood cells
Blood cancers, such as leukemia and myeloproliferative neoplasms, and lymphomas, such as Hodgkin's disease
Metabolic disorders, such as Gaucher's disease and Niemann-Pick disease
Pressure on the veins in the spleen or liver or a blood clot in these veins
How the spleen works
Your spleen is tucked under your rib cage next to your stomach on the left side of your abdomen. It's a soft, spongy organ that performs several critical jobs. Your spleen:
Filters out and destroys old, damaged blood cells
Prevents infection by producing white blood cells (lymphocytes) and acting as a first line of defense against disease-causing organisms
Stores red blood cells and platelets, which help your blood clot
An enlarged spleen affects each of these vital functions. As your spleen grows larger, it filters normal red blood cells as well as abnormal ones, reducing the number of healthy cells in your bloodstream. It also traps too many platelets.
Excess red blood cells and platelets eventually can clog your spleen and affect normal functioning. An enlarged spleen may even outgrow its own blood supply, which can damage or destroy sections of the organ.
Anyone can develop an enlarged spleen at any age, but certain groups are at higher risk, including:
Children and young adults with infections, such as mononucleosis
People who have Gaucher's disease, Niemann-Pick disease, and several other inherited metabolic disorders affecting the liver and spleen
People who live in or travel to areas where malaria is common
Potential complications of an enlarged spleen are:
Infection. An enlarged spleen can reduce the number of healthy red blood cells, platelets and white cells in your bloodstream, leading to more frequent infections. Anemia and increased bleeding also are possible.
Ruptured spleen. Even healthy spleens are soft and easily damaged, especially in car crashes. The possibility of rupture is much greater when your spleen is enlarged. A ruptured spleen can cause life-threatening bleeding into your abdominal cavity.
An enlarged spleen is usually detected during a physical exam. Your doctor can often feel it by gently examining your left upper abdomen. However, in some people — especially those who are slender — a healthy, normal-sized spleen can sometimes be felt during an exam.
Your doctor may confirm the diagnosis of an enlarged spleen with one or more of these tests:
Blood tests, such as a complete blood count to check the number of red blood cells, white blood cells and platelets in your system
Ultrasound or computerized tomography (CT) scan to help determine the size of your spleen and whether it's crowding other organs
Magnetic resonance imagining (MRI) to trace blood flow through the spleen
Imaging tests aren't always needed to diagnose an enlarged spleen. But if your doctor recommends imaging, you generally don't need any special preparation for an ultrasound or MRI.
If you're having a CT scan, however, you may need to refrain from eating before the test. If you need to prepare, your doctor will let you know well in advance.
Finding the cause
Sometimes you may need more testing to find the cause of an enlarged spleen, including liver function tests and a bone marrow exam. These tests can provide more-detailed information about your blood cells than can blood drawn from a vein.
A sample of solid bone marrow is sometimes removed in a procedure called a bone marrow biopsy. Or you may have a bone marrow aspiration, which removes the liquid portion of your marrow. In many cases, both procedures are performed at the same time (bone marrow exam).
Both the liquid and solid bone marrow samples are usually taken from the pelvis. A needle is inserted into the bone through an incision. You'll receive either general or local anesthesia before the test to ease discomfort.
A needle biopsy of the spleen is very rare because of the risk of bleeding.
Occasionally, your doctor may recommend surgery to remove your spleen when there's no identifiable cause for the enlargement. After surgical removal, the spleen is examined under a microscope to check for possible lymphoma of the spleen.
Treatment for an enlarged spleen focuses on the underlying problem. For example, if you have a bacterial infection, treatment will include antibiotics.
If you have an enlarged spleen but don't have any symptoms and the cause can't be found, your doctor may suggest watchful waiting. You'll have to see your doctor for reevaluation in six to 12 months or sooner if you develop any symptoms.
Spleen removal surgery
If an enlarged spleen causes serious complications or the cause can't be identified or treated, surgical removal of your spleen (splenectomy) may be an option. In chronic or critical cases, surgery may offer the best hope for recovery.
Elective spleen removal requires careful consideration. You can live an active life without a spleen, but you're more likely to contract serious or even life-threatening infections after spleen removal. Sometimes radiation can shrink your spleen so that you can avoid surgery.
Reducing infection risk after surgery
After spleen removal, certain steps can help reduce your risk of infection, including:
A series of vaccinations both before and after the splenectomy. These include the pneumococcal (Pneumovax 23), meningococcal and haemophilus influenzae type b (Hib) vaccines, which protect against pneumonia, meningitis and infections of the blood, bones and joints. You'll also need the pneumococcal vaccine every five years after surgery.
Taking penicillin or other antibiotics after your operation and anytime you or your doctor suspects the possibility of an infection.
Calling your doctor at the first sign of a fever, because this may indicate an infection.
Avoiding travel to parts of the world where certain diseases, such as malaria, are common.
Lifestyle and home remedies
Avoid contact sports — such as soccer, football and hockey — and limit other activities as recommended by your doctor. Modifying your activities can reduce the risk of a ruptured spleen.
It's also important to wear a seat belt. If you're in a car accident, a seat belt can help prevent injury to your spleen.
Finally, be sure to keep your vaccinations up to date because your risk of infection is increased. That means at least an annual flu shot, and a tetanus, diphtheria and pertussis booster every 10 years. Ask your doctor if you need any additional vaccines.