Acute cholecystitis

Summary

Acute cholecystitis is an inflammatory condition of the gallbladder, most commonly caused by gallstone obstruction of the cystic duct (90-95% of cases). It presents with persistent right upper quadrant (RUQ) pain lasting >4-6 hours, fever, and positive Murphy's sign. Diagnosis is primarily clinical, supported by ultrasound findings of gallbladder wall thickening >4mm, pericholecystic fluid, and gallstones. Early laparoscopic cholecystectomy within 72 hours is the standard treatment. Complications include gangrene, perforation, and empyema. Acalculous cholecystitis, occurring in critically ill patients, represents 5-10% of cases and carries higher mortality.

Definition

• Acute cholecystitis: Acute inflammation of the gallbladder wall
• Results from cystic duct obstruction in ~90-95% of cases (calculous cholecystitis)
• 5-10% occur without gallstones (acalculous cholecystitis) - typically in critically ill patients
• Most frequent complication of gallstone disease
• Distinguished from biliary colic by:
  • Duration of pain (>4-6 hours vs <4 hours)
  • Presence of inflammatory signs (fever, leukocytosis)
  • Gallbladder wall changes on imaging

Types of Acute Cholecystitis

• Calculous – most common
• Acalculous – 5–10%, in critically ill patients
• Emphysematous
• Gangrenous
• Empyema
• Chronic cholecystitis – chronic inflammatory infiltration on histopathology

Risk Factors

• For Calculous Cholecystitis - follows the "4 F's" rule:
  • Female
  • Forty (age >40) 
  • Fertile (pregnancy, OCP use)
  • Fat (obesity, rapid weight loss)
• Additional risk factors:
  • Hemolytic disorders (sickle cell disease) → pigment stones
  • Total parenteral nutrition (TPN) → bile stasis
  • Diabetes mellitus
  • Hyperlipidemia
  • Fibrate medications (↓ bile acid synthesis)
  • Crohn's disease (terminal ileum involvement)
• For Acalculous Cholecystitis:
  • Critical illness (shock, sepsis, burns)
  • Major surgery (especially cardiac, abdominal)
  • Prolonged fasting/TPN
  • Mechanical ventilation
  • Immunosuppression

Pathophysiology

• Initial cause: cystic duct obstruction → gallbladder distention, wall edema.
• Irritant: lysolecithin (from bile lecithin via phospholipase A), released by mucosal trauma.
• Wall findings: thickened, erythematous, subserosal hemorrhage; pericholecystic fluid.
• 5–10% progress to ischemia, necrosis; perforation usually contained by omentum.
• Bacterial infection in ~50% (E. coli most common); only 15–30% have infected bile.

• Initiating event: Cystic duct obstruction by gallstone
  • Bile stasis → gallbladder distension
  • Increased intraluminal pressure
  • Venous and lymphatic compromise
• Inflammatory cascade:
  • Mucosal trauma releases phospholipase A
  • Lecithin → lysolecithin (mucosal irritant)
  • Prostaglandin-mediated inflammation
  • Neutrophilic infiltration of gallbladder wall
• Secondary bacterial infection (in 50% of cases; only 15–30% have infected bile):
  • E. coli (most common)
  • Klebsiella, Enterococcus
  • Bacteroides (anaerobe)
• Natural progression:
  • Edema → Ischemia → Gangrene → Perforation
  • 5-10% progress to gangrene/perforation if untreated

Clinical Presentation

• Classic triad:
  • RUQ pain
  • Fever
  • Leukocytosis
• Pain characteristics:
  • Persistent RUQ or epigastric pain >4-6 hours (unlike biliary colic <4 hours)
  • May radiate to right shoulder/scapula (phrenic nerve irritation)
  • Worsens with fatty meals
  • Associated with nausea/vomiting
• Physical examination:
  • Murphy's sign: Inspiratory arrest during RUQ palpation (65% sensitivity, 87% specificity)
  • Boas' sign: Hyperesthesia below right scapula
  • RUQ tenderness with guarding
  • Palpable gallbladder mass (20% of cases)
  • Low-grade fever (38-38.5°C)

Diagnosis

• Laboratory findings:
  • Leukocytosis (12,000-15,000/μL); >20,000 suggests complications
  • Mild transaminase elevation (<3x normal)
  • Bilirubin usually <4 mg/dL (if >4, consider choledocholithiasis or Mirizzi syndrome)
  • Alkaline phosphatase mildly elevated
  • Amylase/lipase normal (if elevated, consider gallstone pancreatitis)
• Imaging studies:
  • Ultrasound (first-line):
    • Gallbladder wall thickening >4 mm (most specific)
    • Pericholecystic fluid
    • Gallstones or sludge
    • Sonographic Murphy's sign
    • Gallbladder distension
    • Sensitivity: 81%, Specificity: 83%
  • HIDA scan (Hepatobiliary scintigraphy) (gold standard):
    • Gold standard when ultrasound equivocal
    • Non-visualization of gallbladder after 4 hours = positive
    • Sensitivity: 97%, Specificity: 94%
    • False positives: prolonged fasting, TPN, chronic cholecystitis
  • CT scan:
    • Better for complications (perforation, abscess)
    • Shows gas in gallbladder wall (emphysematous cholecystitis)
    • Alternative diagnoses

Differential Diagnosis

Management

• Initial supportive care:
  • NPO (bowel rest) منع الأكل والشرب
  • IV fluids for hydration
  • Pain control (NSAIDs or opioids)
  • Antiemetics for nausea
  • NG decompression if severe vomiting
• Antibiotic therapy:
  • Indicated for moderate/severe cases or high-risk patients
  • Coverage for gram-negative and anaerobes:
  • Options:
    • Piperacillin-tazobactam
    • Ceftriaxone + metronidazole
    • Ciprofloxacin + metronidazole
• Definitive treatment:
  • Early laparoscopic cholecystectomy within 72 hours 
    • Standard of care for acute cholecystitis
    • Lower morbidity than delayed surgery
    • Shorter hospital stay
    • Conversion to open: 5-10%
  • Percutaneous cholecystostomy (drainage):
    • For high-risk surgical patients
    • Bridge to elective cholecystectomy
    • Keep drain 3-6 weeks minimum
    • Interval cholecystectomy after 6-8 weeks

Complications

• Gangrene, perforation, empyema, abscess, fistula, and gallstone ileus.

Special Considerations

• Pregnancy:
  • Second most common non-obstetric surgical emergency
  • Laparoscopic cholecystectomy safe in all trimesters
  • Best timing: second trimester

Key Takeaways