What are the causes of splenic abscesses?

Causes of Splenic Abscess

Splenic abscesses most commonly arise from infective endocarditis (the single most common antecedent infection), followed by hematogenous seeding from distant infections, immunocompromised states (particularly leukemia), hemoglobinopathies, non-penetrating abdominal trauma, and gastrointestinal malignancies. 1

Primary Infectious Sources

Infective Endocarditis

• Infective endocarditis is the most common single antecedent infection leading to splenic abscess, occurring in 40% of left-sided endocarditis cases, though only 5% progress to abscess formation 2, 1
• Viridans streptococci and S. aureus each account for 40% of splenic abscess cases in endocarditis, with enterococci responsible for 15% 3
• The mechanism involves septic emboli from infected heart valves that lodge in splenic tissue 4

Hematogenous Spread from Distant Infections

• Splenic abscess occurs after hematogenous spread or local dissemination from other primary infection sites 5
• Blood cultures are positive in only 24-80% of cases, indicating that many abscesses result from transient bacteremia 5
• The spleen becomes secondarily infected when ischemic infarcts develop and subsequently become infected 4

Host-Related Risk Factors

Immunocompromised States

• Most patients with splenic abscess are immunocompromised (72%), making this the dominant risk factor 6
• Leukemia is the most common associated condition in splenic abscess patients 6
• Immunosuppression is a major risk factor that predisposes the spleen to abscess formation 4

Hemoglobinopathies

• Hemoglobinopathies predispose the spleen to abscess formation through splenic infarction and subsequent infection 1
• These conditions create areas of ischemic tissue that are vulnerable to bacterial seeding 1

Trauma-Related Causes

Non-Penetrating Abdominal Trauma

• Non-penetrating abdominal trauma appears to predispose the spleen to abscess formation 1
• Trauma creates splenic infarction that can progress to abscess, particularly when persistent fever, recurrent bacteremia, or other signs of sepsis develop 7
• The mechanism involves tissue damage and hematoma formation that becomes secondarily infected 4

Gastrointestinal Sources

Gastrointestinal Malignancy and Pathology

• Gastrointestinal malignancy predisposes to splenic abscess formation 1
• Local dissemination from adjacent abdominal infections can seed the spleen 5

Microbiological Causes

Bacterial Pathogens

• Enterobacteriaceae, gram-positive cocci, and anaerobes are the most frequently involved organisms 5
• Blood cultures are positive in only 24% of patients, while abscess culture after drainage is more efficient (50-80%) 6, 5
• Rare causes include tuberculosis, salmonella, and even Plasmodium vivax in immunocompetent patients 8

Common Clinical Pitfalls

• Do not rely solely on blood cultures, as they are positive in only 24-80% of cases; percutaneous drainage with culture is more diagnostic 5
• Splenic abscess should be suspected in any febrile patient with left upper quadrant tenderness and leukocytosis, regardless of whether a clear source is identified 6
• The nonspecific clinical picture makes this a diagnostic challenge, requiring high clinical suspicion 6
• Clinical splenomegaly is present in only 30% of cases and is not a reliable indicator 2