What are the symptoms of spontaneous bacterial peritonitis?

Symptoms of Spontaneous Bacterial Peritonitis (SBP)

Patients with spontaneous bacterial peritonitis commonly present with abdominal pain, abdominal tenderness, fever, and signs of systemic inflammation, but up to one-third of cases may be asymptomatic or present with only worsening of liver function or hepatic encephalopathy. 1

Classic Symptoms and Signs of SBP

Local Abdominal Symptoms

• Abdominal pain (diffuse or localized)
• Abdominal tenderness on palpation (with or without rebound tenderness)
• Ileus (decreased bowel sounds, nausea, vomiting)
• Diarrhea
• Abdominal distension (worsening of pre-existing ascites) 1, 2

Systemic Inflammatory Responses

• Fever or hypothermia
• Chills
• Altered white blood cell count (leukocytosis or leukopenia)
• Tachycardia
• Tachypnea 1

Non-Specific Manifestations

• Worsening of liver function (increasing jaundice)
• Hepatic encephalopathy (new onset or worsening)
• Acute kidney injury
• Shock (hypotension, poor peripheral perfusion)
• Gastrointestinal bleeding 1, 3

Important Clinical Considerations

1. Silent Presentation: Up to one-third of SBP cases may be completely asymptomatic or present with only subtle clinical deterioration 1, 3

2. High Clinical Suspicion: SBP should be suspected whenever a patient with cirrhosis and ascites deteriorates clinically, even without specific abdominal symptoms 1

3. Diagnostic Accuracy: Clinical features alone have a sensitivity of 92% and specificity of 86% for diagnosing SBP, making them valuable when laboratory confirmation is delayed 4

4. Differential Diagnosis: Secondary bacterial peritonitis (due to perforation or inflammation of intra-abdominal organs) should be suspected with localized abdominal symptoms, multiple organisms on culture, very high neutrophil count, or inadequate response to therapy 1

5. Rapid Diagnosis: Diagnostic paracentesis is mandatory for all cirrhotic patients with ascites at hospital admission and whenever infection is suspected, as delay in diagnosis increases mortality by approximately 3.3% per hour 1, 3

Diagnostic Algorithm

1. Suspect SBP in any cirrhotic patient with ascites who presents with:

   • Abdominal pain or tenderness
   • Fever or hypothermia
   • Unexplained clinical deterioration
   • New or worsening encephalopathy
   • Acute kidney injury
   • Gastrointestinal bleeding 1, 3

2. Perform immediate diagnostic paracentesis to analyze ascitic fluid for:

   • Neutrophil count (>250/mm³ confirms SBP)
   • Culture (bedside inoculation into blood culture bottles)
   • Protein, glucose, LDH (to differentiate from secondary peritonitis) 1, 3

3. Obtain blood cultures simultaneously to increase the chance of isolating the causative organism 1

4. Initiate empiric antibiotic therapy immediately after diagnosis, as mortality increases by 10% for every hour's delay in treatment 1

The high clinical suspicion and prompt diagnostic paracentesis are crucial for early diagnosis and treatment of SBP, which has significantly reduced mortality from over 90% to approximately 20% in recent years 1, 5.