Symptoms of Spontaneous Bacterial Peritonitis
Patients with spontaneous bacterial peritonitis frequently present with fever, abdominal pain, and altered mental status, but up to one-third may be completely asymptomatic, making diagnostic paracentesis mandatory in all hospitalized cirrhotic patients with ascites regardless of symptoms. 1
Clinical Presentation Spectrum
Common Symptomatic Presentations
Patients with SBP may present with any combination of the following manifestations 1:
Local peritoneal symptoms:
- Abdominal pain (occurs in 74-95% of symptomatic cases) 2
- Abdominal tenderness on palpation with or without rebound tenderness 1, 2
- Vomiting 1
- Diarrhea 1
- Ileus 1
Systemic inflammatory signs:
Decompensation of liver disease:
- Worsening hepatic encephalopathy or new-onset confusion 1
- Progressive jaundice or worsening liver function 1
- Acute kidney injury or renal failure 1
- Shock 1
- Gastrointestinal bleeding 1
The Critical Asymptomatic Presentation
A major clinical pitfall is that SBP may be entirely asymptomatic, particularly in outpatients, with up to one-third of patients presenting without any abdominal symptoms or only non-abdominal manifestations such as isolated encephalopathy or acute kidney injury. 1, 2 This asymptomatic presentation is why the American Association for the Study of Liver Diseases mandates diagnostic paracentesis in all cirrhotic patients with ascites upon emergency hospitalization, regardless of the presence or absence of symptoms. 1, 2
Diagnostic Approach
Because typical symptoms may be absent and any clinical deterioration in a cirrhotic patient with ascites should raise suspicion for SBP, diagnostic paracentesis is mandatory in all patients with cirrhosis requiring hospital admission. 1 The diagnosis is confirmed when ascitic fluid neutrophil count exceeds 250 cells/mm³ in the absence of a surgically treatable source of infection. 1
Time-Critical Consideration
In patients with septic shock from suspected SBP, mortality increases by 10% for every hour's delay in initiating antibiotics, making empirical treatment essential even when abdominal pain is subtle or absent. 1, 2 Workup should be initiated promptly, and if suspicion for infection is strong (particularly with systemic inflammatory response or hemodynamic instability), empirical antibiotic therapy should be started immediately after samples for cultures have been collected. 1
Key Clinical Pitfalls to Avoid
Never rely on the presence of symptoms to rule in or rule out SBP - the high frequency of asymptomatic presentations means that absence of fever, abdominal pain, or tenderness does not exclude the diagnosis. 1, 2
Maintain a low threshold for diagnostic paracentesis in any cirrhotic patient with ascites who appears clinically unwell, even with vague or non-specific complaints. 1, 2
Do not wait for culture results - culture-negative neutrocytic ascites (neutrophil count >250 cells/mm³ with negative culture) occurs in up to 60% of cases and requires identical treatment to culture-positive SBP. 1