What are the symptoms and treatment of peritonitis?

Peritonitis: Symptoms and Treatment

Clinical Symptoms

Peritonitis presents with abdominal pain and tenderness in 74-95% of patients, typically accompanied by rebound tenderness and guarding, with abdominal rigidity being the most specific finding that strongly suggests peritoneal inflammation. 1, 2

Cardinal Symptoms

• Abdominal pain and tenderness with rebound tenderness and guarding (74-95% of cases) 1, 2
• Abdominal rigidity - the most specific physical finding 2
• Fever greater than 38.5°C (38% of patients) 1, 2
• Nausea and vomiting (35% of patients) 2
• Abdominal distension with decreased bowel sounds 1, 2

Vital Sign Changes

• Tachycardia (62.5% of patients) - NOT bradycardia 1, 2
• Hypotension indicating progression to septic shock 2
• Tachypnea as part of systemic inflammatory response 2

Laboratory Abnormalities

• Leukocytosis with left shift (band neutrophils >20%) 1, 2
• Elevated C-reactive protein 1, 2
• Increased serum creatinine (>50% above baseline) 1, 2
• Elevated serum lactate indicating tissue hypoperfusion 1, 2

Ascitic Fluid Findings (When Present)

• Polymorphonuclear leukocyte (PMN) count >250/mm³ is diagnostic for spontaneous bacterial peritonitis 3
• Low glucose (<50 mg/dL) suggests secondary peritonitis 3, 1
• Elevated LDH and high total protein (≥1 g/dL) suggest secondary peritonitis 3

Distinguishing Primary vs. Secondary Peritonitis

Primary (Spontaneous) Bacterial Peritonitis

• Occurs in cirrhotic patients with ascites without gastrointestinal perforation 1
• Single organism on culture 1
• PMN count >250/mm³ in ascitic fluid 3

Secondary Peritonitis

Secondary peritonitis should be suspected when multiple organisms are cultured, ascitic PMN count exceeds 1,000/mm³, or when imaging shows free air or bowel perforation. 3, 1

Key differentiating features include:

• Multiple organisms on Gram stain or culture 3
• PMN count >1,000/mm³ 3
• Ascitic glucose <50 mg/dL 3, 1
• Ascitic LDH above normal serum upper limit 3
• Elevated CEA (>5 ng/mL) or alkaline phosphatase (>240 U/L) 3
• Failure of PMN count to decrease after 48 hours of antibiotics 3

Treatment Approach

Spontaneous Bacterial Peritonitis

For suspected spontaneous bacterial peritonitis, initiate empirical therapy with intravenous cefotaxime 2 g every 8 hours or ceftriaxone 1 g every 12-24 hours immediately, even before culture results are available. 3

Antibiotic Therapy

• Cefotaxime 2 g IV every 8 hours (first-line, resolution rate 69-98%) 3
• Ceftriaxone 1 g IV every 12-24 hours (alternative, resolution rate 73-100%) 3
• Treatment duration: 5-10 days depending on clinical response 3
• Oral ofloxacin 400 mg twice daily may substitute for IV therapy in stable patients without prior quinolone exposure, vomiting, shock, or grade II hepatic encephalopathy 3

Albumin Administration

• Albumin infusion reduces renal failure and mortality in SBP patients 1

Indications to Treat

• PMN count >250/mm³ regardless of symptoms 3
• PMN count <250/mm³ WITH fever >37.8°C (100°F), abdominal pain, or tenderness - treat empirically while awaiting cultures 3

Secondary Peritonitis

Secondary peritonitis requires both surgical source control and broad-spectrum antibiotics covering aerobic, anaerobic, and potentially resistant organisms. 1, 4

Source Control (Essential)

• Immediate surgical intervention for perforation or abscess 1, 5
• Damage control surgery in life-threatening situations 4
• Drainage, debridement, and abdominal cleansing 1, 4
• CT imaging to identify perforation or abscess when diagnosis uncertain 3, 1

Antibiotic Coverage

For community-acquired secondary peritonitis, use meropenem 1 g IV every 8 hours, which covers the causative organisms including E. coli, Klebsiella, Pseudomonas, Bacteroides fragilis, and Peptostreptococcus species. 6

Alternative regimens based on severity:

• Moderate cases: Cefoxitin, amoxicillin-clavulanate + gentamicin, or piperacillin-tazobactam 7
• Severe/nosocomial cases: Imipenem + amikacin 7
• Add anaerobic coverage (already included in above regimens) 3, 7
• Consider antifungal therapy (fluconazole) in nosocomial/tertiary peritonitis until cultures available 7, 4

Duration

• 48 hours to 14 days depending on severity and clinical response 7

Critical Pitfalls to Avoid

• Do NOT delay antibiotics - mortality increases significantly with treatment delay 1, 4
• Do NOT perform unnecessary laparotomy in cirrhotic patients with SBP - differentiate from secondary peritonitis first 3
• Do NOT assume bradycardia - tachycardia is the expected finding 1, 2
• Do NOT miss secondary peritonitis - if PMN count doesn't decrease after 48 hours of antibiotics or if multiple organisms are present, pursue imaging and surgical consultation 3
• Do NOT forget renal dosing - adjust antibiotics for creatinine clearance <50 mL/min 6

Monitoring and Follow-up

• Repeat paracentesis is NOT routinely needed in typical SBP with good clinical response 3
• Repeat paracentesis IS indicated when setting, symptoms, organisms, or response are atypical 3
• Monitor for complications: renal failure, hepatic encephalopathy, septic shock, and multi-organ failure 1, 2