Key Facts

Acute cholecystitis is the most common complication of gallstone disease. Early surgical intervention has been shown to be superior to delayed surgery and is now the standard of care in most centres.

Epidemiology

Approximately 20% of patients with symptomatic gallstones develop acute cholecystitis. ~20,000 emergency cholecystectomies per year in England. Acalculous cholecystitis accounts for ~10% and is seen in critically ill patients.

Aetiology

• Calculous (90%): gallstone impaction in cystic duct → obstruction → biliary stasis → secondary bacterial infection (E. coli, Klebsiella, Enterococcus)
• Acalculous (10%): gallbladder ischaemia/stasis — critical illness, major surgery, TPN, HIV, immunosuppression

Pathophysiology

Cystic duct obstruction → gallbladder distension → increased intraluminal pressure → mucosal ischaemia → prostaglandin release → inflammation. Secondary bacterial infection develops in ~50-75%. If untreated: empyema (pus-filled gallbladder), gangrenous cholecystitis, perforation, pericholecystic abscess, gallbladder-duodenal fistula (→ gallstone ileus).

Typical Presentation

• Persistent RUQ/epigastric pain (>6 hours — differentiates from biliary colic)
• Fever (38-39°C)
• Nausea, vomiting
• Positive Murphy's sign: inspiratory arrest on deep palpation of RUQ
• RUQ guarding, palpable gallbladder/mass in ~30%

Complications

• Empyema: swinging fevers, very tender gallbladder, systemic sepsis
• Gangrenous cholecystitis: may paradoxically have less pain (nerve death); high perforation risk
• Perforation: peritonitis, sepsis
• Mirizzi syndrome: common hepatic duct compression by impacted cystic duct stone → obstructive jaundice

Red Flags

• Sepsis (tachycardia, hypotension, fever >39°C)
• Generalised peritonitis (perforation)
• Jaundice (concomitant choledocholithiasis or Mirizzi)
• Palpable tense RUQ mass (empyema)

Bedside

• Murphy's sign: positive
• Observations: temperature, pulse, BP

Bloods

• FBC: leucocytosis (WCC >11 × 10⁹/L)
• CRP: raised
• LFTs: mildly raised ALP/GGT; if bilirubin raised → suspect CBD stone or Mirizzi
• Amylase/lipase: exclude pancreatitis
• Blood cultures: if septic

Imaging

• USS abdomen: first-line — gallstones, wall thickening >3 mm, pericholecystic fluid, sonographic Murphy's sign, CBD dilatation
• CT abdomen: if USS equivocal or complications suspected (perforation, abscess)
• MRCP: if CBD stones suspected (jaundice, dilated CBD)
• HIDA scan: if acalculous cholecystitis suspected (non-filling of gallbladder confirms cystic duct obstruction)

Special Tests

• Tokyo Guidelines (TG18): severity grading
  • Grade I (mild): no organ dysfunction, no severe local inflammation
  • Grade II (moderate): WCC >18, palpable mass, duration >72 hours, marked local inflammation
  • Grade III (severe): cardiovascular, neurological, respiratory, renal, hepatic, or haematological dysfunction

Non-pharmacological

• NBM, IV fluids
• VTE prophylaxis

Pharmacological

• IV antibiotics: co-amoxiclav 1.2 g TDS; OR cefuroxime 1.5 g TDS + metronidazole 500 mg TDS; OR piperacillin-tazobactam 4.5 g TDS if severe
• Analgesia: paracetamol + NSAID (diclofenac) + opioid (morphine titrated)
• Anti-emetics: ondansetron, cyclizine

Surgical/Interventional

• Early laparoscopic cholecystectomy: within 72 hours of admission — gold standard (ACDC trial, CHOCOLATE trial support early over delayed surgery; shorter total hospital stay, similar complication rates)
• Delayed cholecystectomy: 6-8 weeks later (if early surgery not feasible); higher complication rates and ~20% readmission rate while waiting
• Subtotal cholecystectomy: if Calot's triangle inflammation too severe for complete dissection ("critical view of safety" not achievable)
• Percutaneous cholecystostomy: temporary gallbladder drainage for patients unfit for surgery (Grade III, significant comorbidity); bridge to interval cholecystectomy
• ERCP: if concomitant CBD stones

Referral Criteria

• All acute cholecystitis: emergency surgical team
• Early cholecystectomy: within 72 hours where possible
• Interventional radiology: percutaneous cholecystostomy if unfit for surgery
• ERCP: suspected CBD stones (jaundice, dilated CBD)

Uncomplicated acute cholecystitis treated with early cholecystectomy has mortality <1% and complication rate <10%. Delayed cholecystectomy has ~20% readmission rate before surgery. Gangrenous cholecystitis occurs in 2-30% of cases. Perforation has 10-15% mortality. Acalculous cholecystitis has higher mortality (~30%) due to underlying critical illness and delayed diagnosis. Bile duct injury rate during cholecystectomy for acute cholecystitis is ~0.5-1%.

Tokyo Guidelines (TG18) Severity and Management

Critical View of Safety (CVS)

• Described by Strasberg (1995)
• Required before clipping/cutting any structures in Calot's triangle
• 3 criteria: (1) hepatocystic triangle cleared, (2) lower 1/3 of gallbladder freed from liver bed, (3) only 2 structures entering gallbladder visible
• Reduces bile duct injury risk