Acute Acalculous Cholecystitis

Acute acalculous cholecystitis is an acute inflammation of the gallbladder in the absence of gallstones, typically occurring in critically ill or physiologically stressed patients due to gallbladder stasis, ischemia, or infection.

I. Epidemiology

• Accounts for 5–10% of cholecystitis in adults
• Represents up to 50–60% of cases in children, especially during infectious illness

II. Associated Conditions

• Sepsis
• Gastroenteritis
• Abdominal trauma or surgery
• Extensive burns
• Shock and cardiac resuscitation
• IV nutrition and prolonged fasting
• Systemic inflammatory diseases:
  • Systemic lupus erythematosus
  • Kawasaki disease
  • Polyarteritis nodosa
• Malignancy
• Congestive heart failure

III. Pathophysiology

Root causes include gallbladder stasis or ischemia.

Risk Factors

• Prolonged fasting
• Total parenteral nutrition (TPN)
• IV opiate narcotics
• Volume depletion
• Multiple transfusions
• Sepsis

Infectious Etiologies in Healthy Children

• Viruses: Hepatitis A, Epstein-Barr virus, cytomegalovirus
• Bacteria: Salmonella, Staphylococcus aureus, Coxiella burnetii, Brucella melitensis
• Parasites: Plasmodium falciparum/vivax

Mechanisms

• Infection → intrahepatic cholestasis → altered bile → mucosal injury
• Dehydration → concentrated bile → injury from bile acids and enzymes

IV. Clinical Features

• Fever
• RUQ abdominal pain
• Vomiting
• Leukocytosis (70–80%)
• Elevated bilirubin and transaminases (60%)
• RUQ mass (25% in one pediatric study)

V. Radiographic Features

Ultrasound (≥2 findings, no stones)

• Gallbladder distension
• Wall thickening (>3.5–4 mm)
• Sludge (no stones)
• Pericholecystic fluid
• Sonographic Murphy sign
• Intramural gas (rare)
• Abscess or perforation (rare)

HIDA Scan

• Normal hepatic uptake with non-opacification of gallbladder
• Rim sign: pericholecystic radiotracer accumulation → think gangrene
• Tracer leakage into fossa → think perforation

VI. Management

Medical Therapy

• Empiric antibiotics recommended until viral etiology confirmed
• Serial ultrasounds to monitor progression and complications

Conservative Management

• Successful in 30–75% of children (30-75%!?! seriously guys, we need better studies!)
  
• Especially effective in viral AAC
• Supportive care: hydration, pain control, monitoring

Interventional Options

• Percutaneous cholecystostomy w/ drainage for critically ill patients
• Cholecystectomy for persistent or complicated cases