Splenic Abscess
A splenic abscess is a localized collection of pus within the spleen, usually caused by infection that has spread through the bloodstream from another site, by direct extension from a nearby infection, or by infection of a preexisting splenic lesion or hematoma. Splenic abscesses are uncommon but potentially serious, and prompt diagnosis is critical because untreated infections can lead to sepsis or rupture. Imaging—particularly CT and ultrasound—is central to diagnosis, and treatment usually combines antibiotics with image-guided drainage and—when needed—surgery.
What is it?
A splenic abscess is a localized collection of pus within the spleen, formed when bacteria, fungi, or—less commonly—parasites infect splenic tissue and the body’s immune response walls off the infection within a defined area. Splenic abscesses are relatively uncommon compared with abscesses in other abdominal organs but are clinically important because they often occur in patients who are already significantly ill and because untreated infection can lead to sepsis, splenic rupture, or other serious complications.
Splenic abscesses develop through several main mechanisms. Hematogenous spread—infection traveling through the bloodstream from another site—is the most common route, particularly in patients with infective endocarditis, severe systemic infections, IV drug use, urinary tract infections, abdominal infections, or other sources of bacteremia. Direct extension from nearby infections—such as those involving the pancreas, stomach, colon, or left kidney—is another important mechanism. Infection of preexisting splenic lesions (such as cysts, hematomas, or infarcts) can also produce abscesses, particularly after trauma or in patients with predisposing conditions. Less commonly, splenic abscesses can develop after splenic artery embolization or other procedures, or as part of broader fungal or parasitic disease.
Risk factors that significantly increase the likelihood of splenic abscess include immunosuppression (such as from HIV/AIDS, chemotherapy, transplant medications, or chronic steroids), diabetes mellitus, sickle cell disease and other conditions associated with functional asplenia or splenic infarcts, IV drug use, infective endocarditis, recent abdominal trauma or surgery, malignancies (particularly hematologic cancers), and chronic medical conditions. In some regions, specific infections—such as tuberculosis, melioidosis, or amebic and fungal diseases—are more common contributors.
The most common organisms causing splenic abscesses include Gram-positive bacteria such as staphylococci and streptococci (often related to endocarditis), Gram-negative bacteria such as Escherichia coli, Klebsiella species, and other enteric organisms (often related to abdominal sources), anaerobes, and—in immunocompromised patients—fungi such as Candida species. Polymicrobial infections are not uncommon. Parasitic causes (such as amebic abscesses) are seen primarily in patients from or with travel to endemic regions.
Symptoms classically include fever (often with chills), upper left abdominal pain (sometimes radiating to the left shoulder via diaphragmatic irritation), nausea, vomiting, fatigue, weight loss, and signs of systemic infection. The classic triad of fever, left upper quadrant pain, and a tender or enlarged spleen is well known but is present in only a minority of patients; many present with more nonspecific features, particularly in the elderly, the immunocompromised, or those with chronic illness. Sepsis and septic shock can develop in severe cases. Some patients with chronic or smoldering infections—such as tuberculosis or fungal disease—may have more gradual symptoms over weeks to months.
Diagnosis combines clinical assessment, laboratory studies, and imaging. Blood tests typically show elevated white blood cell counts (or sometimes low counts in severe infection or immunosuppression), elevated inflammatory markers (CRP and ESR), and abnormalities reflecting sepsis when present. Blood cultures are essential and frequently identify the responsible organism. CT of the abdomen with intravenous contrast is the primary imaging test for splenic abscess and typically shows one or more well-defined, low-density lesions within the spleen, often with a rim of enhancement, internal gas, or surrounding inflammatory changes. Ultrasound may identify many splenic abscesses but is generally less sensitive than CT. MRI with contrast can be useful in select cases, particularly when avoiding radiation or iodinated contrast is preferred. Echocardiography is often performed when infective endocarditis is suspected. Image-guided sampling of the abscess—usually through a needle—provides material for microbiology and helps guide targeted antibiotic therapy, often at the same time as therapeutic drainage. Additional studies are tailored to the suspected underlying source.
Important to Know
Splenic abscess is generally a serious infection that requires prompt diagnosis, hospital admission, and coordinated treatment. The mainstays of management are antibiotic therapy, drainage of the abscess, and treatment of the underlying source of infection, along with supportive care.
Empiric antibiotics—covering common Gram-positive, Gram-negative, and anaerobic organisms—are usually started as soon as splenic abscess is suspected and blood cultures have been obtained. The specific regimen is tailored based on clinical context, suspected source, local resistance patterns, and the patient’s overall health. Once microbiology results are available, antibiotics are narrowed to target the identified organisms. Treatment durations are individualized and typically extend for several weeks, often longer in patients with endocarditis or fungal infection.
Drainage of the abscess is a critical component of management in most patients. Image-guided percutaneous drainage—through a catheter placed under CT or ultrasound guidance—is now the most common first-line treatment for many splenic abscesses and can be highly effective, particularly for single, well-defined abscesses without significant complications. Surgical treatment—including splenectomy, partial splenectomy, or open drainage—is reserved for selected patients, including those with multiple or multiloculated abscesses, large or complicated lesions, abscesses that have ruptured, abscesses caused by certain organisms (such as some fungal infections), or those that fail percutaneous management. Treatment plans are individualized in collaboration with surgeons, interventional radiologists, infectious disease specialists, and others.
Identification and treatment of the underlying source of infection is essential. Infective endocarditis is managed with prolonged antibiotic therapy and—in selected patients—valve surgery. Abdominal sources, urinary sources, and other infections are treated according to standard principles. Underlying conditions such as diabetes, immunosuppression, sickle cell disease, or malignancy are managed in collaboration with the relevant specialists. In patients with IV drug use, addiction treatment and support are important parts of long-term care.
Patients who undergo total splenectomy require specific attention to infection prevention. This includes vaccinations against encapsulated bacteria (such as pneumococcal, meningococcal, and Haemophilus influenzae type b vaccines), antibiotic prophylaxis in selected patients, education about prompt evaluation of fevers, and consideration of travel-related risks. Patients with functional asplenia from chronic conditions such as sickle cell disease require similar preventive measures.
Supportive care—including pain management, hydration, nutritional support, treatment of sepsis when present, monitoring of vital signs and laboratory values, and prevention of complications—is an essential part of inpatient management. Long-term follow-up may include repeat imaging to confirm resolution of the abscess and ongoing management of the underlying condition.
Care is typically coordinated by hospitalists or internal medicine teams, infectious disease specialists, interventional radiologists, general or hepatobiliary surgeons, cardiologists (when endocarditis is involved), hematologists (in patients with sickle cell disease or hematologic conditions), and primary care clinicians. Imaging and laboratory findings are interpreted alongside the patient’s symptoms, examination, and broader clinical context rather than in isolation.
Patient education is important, particularly regarding antibiotic adherence (often involving long courses, sometimes administered through outpatient IV therapy), recognition of warning signs, the importance of follow-up imaging, and preventive measures after splenectomy when applicable.
Red flag symptoms include sudden severe upper left abdominal pain, lightheadedness or fainting, rapid heart rate, cool clammy skin or signs of shock, high fever with rigors, sudden severe shortness of breath, signs of sepsis, sudden severe weakness, confusion, or rapid clinical deterioration. These warrant immediate emergency evaluation, as they may indicate splenic rupture, severe sepsis, or other serious complications.