A spleen that’s working normally is something you never feel or notice. It sits tucked behind your lower left ribs, roughly the size of your fist, quietly filtering old red blood cells out of your blood and producing white blood cells to fight infection. When something goes wrong, the most telling sign is pain or a sense of fullness in your upper left abdomen, sometimes radiating to your left shoulder. But many spleen problems produce no obvious symptoms at all, which is why blood work and imaging often catch the issue before you do.
What Your Spleen Actually Does
Your spleen acts as a blood filter and an immune outpost. It catches and destroys bacteria, viruses, and other microorganisms circulating in your bloodstream, and it removes old or damaged red blood cells that are no longer functioning well. It also produces and stores white blood cells called lymphocytes, which are key players in your immune response. A healthy adult spleen measures roughly 10 to 12 cm long (about 4 to 5 inches) and holds a modest reserve of blood cells. You can live without it, but losing it makes you more vulnerable to certain infections.
Signs of an Enlarged Spleen
The most common spleen problem is enlargement, called splenomegaly. A spleen is considered enlarged when it exceeds about 13 cm in length on imaging. The tricky part: many people with an enlarged spleen have no symptoms at all. When symptoms do appear, the most recognizable ones are:
- Pain or pressure in the upper left abdomen. This can range from a dull ache to sharp discomfort. It sometimes radiates to your left shoulder or back.
- Feeling full after eating very little. An enlarged spleen presses against your stomach from behind, so even a small meal can make you feel stuffed. You may also lose your appetite entirely.
- A palpable lump below your left ribs. Normally, you cannot feel your spleen through your skin. If you can, it has grown significantly beyond its usual size.
Less obvious signs include fatigue, frequent infections, and easy bleeding or bruising. These happen because an oversized spleen can trap too many blood cells, lowering your counts of red cells, white cells, and platelets all at once.
What Causes Spleen Problems
An enlarged or damaged spleen is almost always a downstream effect of something else happening in your body. The most common triggers include viral infections (especially mononucleosis, which is notorious for causing temporary spleen swelling), liver disease such as cirrhosis, and conditions that destroy red blood cells prematurely. Blood cancers like leukemia and lymphoma can also cause the spleen to enlarge as it works overtime to filter abnormal cells.
A less common but serious problem is splenic infarction, where blood flow to part of the spleen gets blocked. This tends to happen in people with blood-clotting disorders, sickle cell disease, heart conditions like atrial fibrillation, or infections of the heart valves. About half of patients with a splenic infarct experience localized left-sided abdominal pain, though roughly a third have no symptoms pointing to the spleen at all. Fever, nausea, and vomiting can accompany it.
How Doctors Check Your Spleen
A physical exam is the starting point. Your doctor will have you lie down, sometimes on your right side with your knees drawn up, and gently feel below your left rib cage while you take a deep breath. In a healthy adult, the spleen should not be palpable unless the person is very thin. If the doctor can feel it, that’s a strong signal it’s enlarged. Doctors can also tap (percuss) a specific area on your left side called Traube’s space. Dullness in that area, rather than the normal hollow sound, raises suspicion of enlargement.
Imaging confirms the diagnosis. Ultrasound is typically the first test ordered because it’s quick, painless, and radiation-free. It can measure the spleen’s dimensions and spot abnormalities in texture. A CT scan with contrast dye provides more detail and is the preferred tool if doctors suspect a splenic infarction (a blocked blood vessel shows up as a wedge-shaped area) or a rupture. MRI is sometimes used in more complex cases. Blood tests often run alongside imaging to check your blood cell counts, liver function, and markers of infection or inflammation.
Signs That Need Immediate Attention
A ruptured spleen is a medical emergency. It typically follows a blow to the abdomen, like a car accident, a sports injury, or a fall, but it can also happen spontaneously if the spleen is already enlarged and fragile (this is why doctors warn people with mono to avoid contact sports). The classic signs are sharp, worsening pain in the left upper abdomen, lightheadedness or fainting, and referred pain to the left shoulder, especially when breathing in. That shoulder pain, called Kehr’s sign, happens because blood from the ruptured spleen irritates the diaphragm, which shares nerve pathways with the shoulder. It’s uncommon but highly suggestive of internal bleeding.
If you experience a combination of increasing left-sided abdominal pain, dizziness, confusion, rapid heartbeat, or that distinctive left shoulder pain, get to an emergency room. These can indicate hemorrhagic shock from internal blood loss, which can become life-threatening quickly.
What to Watch For Day to Day
If you already know you have an enlarged spleen, or you have a condition that puts you at risk for one, pay attention to changes in how you feel after eating. A sudden drop in how much food you can tolerate, new pain on your left side, or unexplained fatigue and bruising are worth reporting to your doctor. Pain that gets worse when you breathe in deeply is a particularly important signal, since it can indicate the spleen is pressing on or irritating nearby structures.
Keep in mind that spleen enlargement is often temporary. If the underlying cause, like a viral infection, resolves, the spleen typically returns to its normal size. But persistent or worsening symptoms deserve follow-up imaging to track whether the spleen is growing, and to make sure nothing more serious is driving the change.