Do you start antibiotics in a patient with equivocal cholecystitis (inflammation of the gallbladder), a dilated common bile duct (CBD) of 9mm on right upper quadrant (RUQ) ultrasound, without leukocytosis (elevated white blood cell count) and negative transaminitis (liver enzyme test), while awaiting magnetic resonance cholangiopancreatography (MRCP) results?

Management of Equivocal Cholecystitis with Dilated CBD

Antibiotics should not be started for equivocal cholecystitis with dilated CBD of 9mm on RUQ ultrasound in the absence of leukocytosis and negative transaminitis while awaiting MRCP results, unless the patient develops signs of sepsis or systemic inflammatory response. 1

Diagnostic Approach for Equivocal Cholecystitis

Initial Assessment

• A dilated CBD of 9mm alone without other clinical or laboratory abnormalities is insufficient to diagnose cholecystitis or cholangitis
• Research shows the prevalence of isolated CBD dilation in cholecystitis and choledocholithiasis is <1% 2
• The diagnosis of cholecystitis should include:
  • Clinical signs (RUQ pain, Murphy's sign, fever)
  • Laboratory findings (indicators of inflammation)
  • Imaging findings (gallbladder wall thickening, pericholecystic fluid) 3

Imaging Pathway

1. Initial imaging: Ultrasound is the first-line imaging technique for suspected acute cholecystitis 3
2. When ultrasound is equivocal and clinical suspicion persists:
   • Proceed with MRCP as recommended in your case 3
   • If MRCP is negative and clinical suspicion persists, HIDA scan is appropriate 3, 1

Antibiotic Decision Algorithm

Do NOT start antibiotics if:

• Patient has equivocal cholecystitis findings
• Normal WBC count
• Normal liver enzymes
• No fever or signs of sepsis
• Awaiting confirmatory imaging 1

START antibiotics immediately if:

• Patient develops fever
• Signs of sepsis or shock appear
• Evidence of biliary peritonitis
• Significant clinical deterioration while awaiting MRCP 3, 1

If Cholecystitis/Cholangitis Is Confirmed

For non-critically ill, immunocompetent patients:

• Amoxicillin/Clavulanate 2g/0.2g q8h 3
• Alternative if beta-lactam allergy: Eravacycline 1 mg/kg q12h or Tigecycline 100 mg LD then 50 mg q12h 3

For critically ill or immunocompromised patients:

• Piperacillin/tazobactam 6 g/0.75 g LD then 4 g/0.5 g q6h or 16 g/2 g by continuous infusion 3
• If septic shock: Consider carbapenems (meropenem, doripenem, or imipenem/cilastatin) 3

Important Considerations

• The presence of a dilated CBD (9mm) without other clinical or laboratory abnormalities has very low diagnostic value for cholecystitis or cholangitis 2, 4
• Empiric antibiotics should be reserved for patients with clear evidence of infection to prevent unnecessary antibiotic exposure and resistance 5, 6
• If MRCP confirms choledocholithiasis or cholangitis, biliary drainage plus appropriate antibiotic therapy will be required 3
• Monitor closely for development of fever, increasing RUQ pain, or signs of systemic inflammatory response while awaiting MRCP results 1

HIDA Scan After Negative MRCP

If MRCP is negative but clinical suspicion for cholecystitis remains high, a HIDA scan should be performed as it has higher sensitivity for detecting gallbladder dysfunction even when structural abnormalities are not evident on other imaging modalities 3, 1