How should paracentesis be performed in patients with known spontaneous bacterial peritonitis (SBP)?

Paracentesis in Known Spontaneous Bacterial Peritonitis (SBP)

In patients with known spontaneous bacterial peritonitis, diagnostic paracentesis should be performed immediately upon hospital admission and repeated if there are signs of infection, with samples sent for neutrophil count and culture to guide antibiotic therapy. 1

Diagnostic Approach

Initial Paracentesis

• Perform diagnostic paracentesis in all cirrhotic patients with ascites at hospital admission to rule out SBP 1
• Additional indications for paracentesis in patients with known or suspected SBP:
  • Gastrointestinal bleeding
  • Shock or signs of systemic inflammation (fever, chills)
  • Gastrointestinal symptoms (pain, vomiting, diarrhea)
  • Worsening liver or renal function
  • Hepatic encephalopathy 1

Laboratory Analysis

• Diagnosis of SBP is based on neutrophil count in ascitic fluid >250/mm³ 1
• Neutrophil count is determined by microscopy but can be substituted with flow cytometry-based automated count 1
• Send ascitic fluid for:
  • Cell count with differential
  • Culture (preferably inoculated into blood culture bottles at bedside)
  • Total protein, LDH, and glucose (to help differentiate SBP from secondary peritonitis) 1
• Obtain blood cultures before starting antibiotics 1

Management Protocol

Antibiotic Therapy

• Initiate empiric antibiotic therapy immediately after diagnosis of SBP 1
• First-line therapy: Third-generation cephalosporin (cefotaxime 2g IV every 8 hours) 1
• Avoid potentially nephrotoxic antibiotics (e.g., aminoglycosides) 1
• Duration: 5-day therapy is as effective as 10-day treatment 1
• Alternative regimens:
  • Amoxicillin/clavulanic acid (IV then oral) 1
  • Oral ofloxacin (400mg twice daily) for patients without vomiting, shock, or grade II+ hepatic encephalopathy 1

Follow-Up Paracentesis

• Follow-up paracentesis is not necessary in all patients with SBP 1
• Consider repeat paracentesis in:
  • Atypical presentation or clinical course
  • Suspected secondary peritonitis
  • Inadequate response to therapy 1
• After 48 hours of treatment, ascitic fluid neutrophil count should be less than 50% of the original value if antimicrobial therapy is appropriate 2

Special Considerations

Secondary Bacterial Peritonitis

• Suspect secondary peritonitis if:
  • Localized abdominal symptoms or signs
  • Multiple organisms on ascitic culture
  • Very high ascitic neutrophil count
  • High ascitic protein concentration
  • Inadequate response to therapy 1
• Additional tests to differentiate from SBP:
  • Ascitic fluid total protein >1 g/dL
  • LDH higher than upper limit of normal for serum
  • Glucose <50 mg/dL 1
• In suspected secondary peritonitis:
  • Obtain prompt CT scanning
  • Consider surgical evaluation
  • Add anaerobic antibiotic coverage 1

Safety Considerations

• Paracentesis is generally safe, but caution is warranted in patients with severe coagulopathy (prothrombin time or partial thromboplastin time more than twice the control value) 3
• The risk of serious hemorrhage is low but can occur, particularly in patients awaiting liver transplantation 3

Emerging Concerns

• Increasing prevalence of gram-positive bacteria and multidrug-resistant organisms 4, 5
• Consider alternative antibiotics (e.g., piperacillin-tazobactam) for nosocomial SBP or when traditional regimens fail 5
• Healthcare-associated and nosocomial SBP infections may require broader antibiotic coverage 5

Prevention of Recurrence

• Patients with prior SBP have a high risk of recurrence (up to 69% within one year) 6
• Consider prophylactic antibiotics (norfloxacin) for patients with:
  • Previous episode of SBP
  • Gastrointestinal bleeding
  • Low ascitic fluid protein (<1.5 g/dL) 1, 6