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For further information, see CMDT Part 15-09: Spontaneous Bacterial Peritonitis

Key Features

Essentials of Diagnosis

  • A history of chronic liver disease and ascites

  • Fever and abdominal pain

  • Peritoneal signs uncommonly encountered on examination

  • Ascitic fluid neutrophil count > 250 white blood cells (WBC)/mcL (0.25 × 109/L)

General Considerations

  • Occurs with few exceptions in patients with ascites caused by chronic liver disease

  • Affects ~20–30% of cirrhotic patients

  • Most common pathogens are enteric gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae) or gram-positive bacteria (Streptococcus pneumoniae, viridans streptococci, Enterococcus)

  • Patients with ascitic fluid total protein of < 1 g/dL are at increased risk

Clinical Findings

Symptoms and Signs

  • Symptoms in 80–90%; asymptomatic in 10–20%

  • Fever and abdominal pain present in two-thirds

  • Change in mental status due to precipitation or exacerbation of hepatic encephalopathy

  • Signs of chronic liver disease with ascites

  • Abdominal tenderness in < 50%

Differential Diagnosis

  • Secondary bacterial peritonitis, eg, appendicitis, diverticulitis, perforated peptic ulcer, perforated gallbladder

  • Peritoneal carcinomatosis

  • Pancreatic ascites

  • Tuberculous ascites


Laboratory Tests

  • Kidney dysfunction, abrupt worsening of kidney function

  • Ascitic fluid polymorphonuclear neutrophil (PMN) count of > 250 cells/mcL (0.25 × 109/L) (neutrocytic ascites) or percentage of PMNs > 50–70% of the ascitic fluid WBC count is presumptive evidence of bacterial peritonitis

  • Ascitic fluid Gram stain and reagent strips are insensitive

  • Ascitic fluid cultures should be obtained by inoculating blood culture bottles at the bedside

  • 10–30% of patients with neutrocytic ascites have negative ascitic bacterial cultures ("culture-negative neutrocytic ascites"), but are presumed nonetheless to have bacterial peritonitis and treated empirically

  • Blood cultures occasionally are positive, which helps identify the organism when ascitic fluid cultures are negative

Imaging Studies

  • Abdominal CT imaging should be obtained to look for evidence of an intra-abdominal source of infection

Diagnostic Procedures

  • Abdominal paracentesis



  • Empiric therapy should be initiated with a third-generation cephalosporin

    • Cefotaxime, 2 g intravenously every 8–12 hours

    • Ceftriaxone, 1–2 g intravenously every 24 hours

    • Combination β-lactam/β-lactamase agent, such as ampicillin/sulbactam 2 g/1 g intravenously every 6 hours

  • Aminoglycosides

    • Recommended duration of antibiotic is 5–10 days or until the ascites fluid PMN count decreases to < 250 cells/mcL (0.25 × 109/L)

    • If the ascitic neutrophil count has not decreased by 25%, antibiotic coverage should be adjusted (guided by culture and sensitivity results, if available) and secondary causes of peritonitis excluded

    • If the ascitic PMN count has decreased but remains > 250 cells/mcL (0.25 × 109/L), antibiotics should be continued for an additional 2–3 days before ...

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