Spontaneous Bacterial Peritonitis & Cirrhotic Emergencies
Comprehensive emergency evaluation and protocolized resuscitation of spontaneous bacterial peritonitis (SBP) and decompensated cirrhotic crises: portosystemic shunting, bacterial translocation from gut lumen to mesenteric lymphatics, diagnostic paracentesis technique and interpretation (absolute neutrophil count [PMN] >= 250/mcL), third-generation cephalosporin therapy (Ceftriaxone/Cefotaxime), mandatory IV 25% Albumin infusion protocol to prevent Type 1 Hepatorenal Syndrome (HRS), differentiating SBP from secondary surgical peritonitis (Runyon's criteria), and bedside ultrasound-guided paracentesis.
Resuscitation Quick Actions • First 2 Minutes
Diagnostic PMN Cutoff
Ascitic fluid absolute polymorphonuclear neutrophil (PMN) count >= 250/mcL (PMN = WBC x % neutrophils) CONFIRMS SBP
Stat Paracentesis Rule
Perform diagnostic paracentesis on ANY cirrhotic patient with ascites presenting with fever, pain, AMS, AKI, or shock
First-Line Antibiotic
Ceftriaxone 2g IV q24h OR Cefotaxime 2g IV q8h; covers E. coli, Klebsiella pneumoniae, and Streptococcus species
Mandatory IV Albumin
Day 1: 1.5 g/kg IV (within 6 hours of diagnosis); Day 3: 1.0 g/kg IV; prevents hepatorenal syndrome and reduces mortality by 65%
Inoculate Blood Culture Bottles
Directly inoculate 10 mL of ascitic fluid into aerobic and anaerobic blood culture bottles at the bedside (boosts culture yield from 40% to 90%)
Runyon's Secondary Peritonitis
Suspect surgical perforation if ascitic fluid has >= 2 of: Glucose < 50 mg/dL, Total Protein > 1.0 g/dL, LDH > upper limit of normal
Hepatic Hydrothorax
Transudative pleural effusion (usually right-sided) in cirrhotic patients with ascites traversing diaphragmatic defects; managed with sodium restriction and diuretics; avoid chest tube placement (causes massive protein and fluid depletion).
Pseudomembranous Colitis (C. difficile)
Severe watery diarrhea, leukocytosis, and abdominal distension post-antibiotic use; fulminant colitis (shock, ileus, megacolon) treated with oral Vancomycin (500 mg QID) + IV Metronidazole (500 mg q8h) + rectal vancomycin enemas.
Bottom-Line Clinical Pearl
Spontaneous Bacterial Peritonitis (SBP) is an acute, life-threatening ascitic fluid infection occurring in cirrhotic patients with ascites, carrying an in-hospital mortality of 20–40%. Signs are notoriously subtle: fever (often low-grade or absent), mild abdominal pain, worsening encephalopathy, or acute kidney injury without any abdominal tenderness. ANY CIRRHOTIC PATIENT WITH ASCITES ADMITTED TO THE ED REQUIRES A DIAGNOSTIC PARACENTESIS! The diagnosis is established when ascitic fluid Absolute Neutrophil Count (PMN = Total Ascitic WBC * % Neutrophils) is >= 250/mcL. Treatment is immediate IV Ceftriaxone (2g IV q24h) or Cefotaxime. Co-administration of IV 25% Albumin (1.5 g/kg on Day 1, followed by 1.0 g/kg on Day 3) is MANDATORY: albumin reduces renal impairment and cuts mortality from 29% to 10%.
Cirrhosis produces severe portal hypertension, splanchnic arterial vasodilation, and intestinal mucosal congestion. This compromises the mucosal barrier, permitting translocation of viable enteric bacteria (primarily gram-negative bacilli: Escherichia coli [40–50%], Klebsiella pneumoniae, and Streptococcus pneumoniae) across bowel walls into mesenteric lymph nodes and the systemic bloodstream via portosystemic shunts.
Cirrhotic ascitic fluid has severely diminished bactericidal opsonic activity due to impaired hepatic synthesis of complement proteins (C3, C4) and low total protein concentrations ($< 1.0\text{ g/dL}$), allowing uninhibited bacterial proliferation within the peritoneal space, precipitating SBP.
| Ascitic Fluid Parameter | Normal Ascites | Spontaneous Bacterial Peritonitis (SBP) | Secondary Bacterial Peritonitis (Surgical Perforation) |
|---|---|---|---|
| Absolute Neutrophil Count (PMN) | $< 250\text{ cells/mcL}$ | $\ge 250\text{ cells/mcL}$ | $\ge 250\text{ cells/mcL}$ (often thousands) |
| Ascitic Total Protein | $< 2.5\text{ g/dL}$ | $< 1.0\text{ g/dL}$ | $> 1.0\text{ g/dL}$ (peritoneal inflammatory exudate) |
| Ascitic Glucose | Equals serum glucose | $> 50\text{ mg/dL}$ (normal) | $< 50\text{ mg/dL}$ (bacteria and neutrophils consume glucose) |
| Ascitic LDH | $< 0.4$ of serum | $< 225\text{ U/L}$ | $>$ Upper limit of normal serum LDH |
| Microbiology Culture | Sterile | Monomicrobial (single organism on culture) | Polymicrobial (multiple enteric organisms and anaerobes on Gram stain) |
Runyon's Modified Criteria for Secondary Peritonitis: If ascitic fluid demonstrates at least 2 of the 3 criteria (Total Protein $> 1.0\text{ g/dL}$, Glucose $< 50\text{ mg/dL}$, LDH $>$ serum normal), suspect secondary peritonitis from a ruptured abdominal viscus (perforated ulcer, perforated diverticulum). Order emergent abdominal CT with IV contrast and obtain an immediate surgical consult: treating secondary surgical peritonitis with antibiotics alone carries a 100% mortality rate.
In a landmark trial by Sort et al. (NEJM), co-administration of intravenous albumin with antibiotics reduced the incidence of Type 1 Hepatorenal Syndrome from 33% to 10% and reduced in-hospital mortality from 29% to 10%:
| Timing of Infusion | Albumin Dosing Regimen | Physiologic Mechanism of Renal Protection |
|---|---|---|
| Day 1 (Within 6 hours of diagnosis) | 1.5 grams/kg IV of 25% Albumin | SBP induces marked systemic vasodilation and worsening effective arterial blood volume. Albumin expands intravascular volume, scavenges nitric oxide and endotoxins, and preserves renal arterial perfusion pressure. |
| Day 3 (48 hours later) | 1.0 gram/kg IV of 25% Albumin | Sustains oncotic expansion and suppresses renin-angiotensin-aldosterone overactivation, preventing acute tubular and functional renal shutdown. |
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