Why was I prescribed rifaximin (generic name) for acalculous cholecystitis evident on a CT (Computed Tomography) scan?

Management of Acalculous Cholecystitis: Why Rifaximin Was Prescribed

Rifaximin is likely prescribed for acalculous cholecystitis to target bacterial overgrowth in the biliary system and reduce inflammation, though this is not considered first-line therapy according to current guidelines. 1

Diagnostic Confirmation of Acalculous Cholecystitis

• Acalculous cholecystitis is typically diagnosed through imaging, with CT scan (as in your case) showing gallbladder inflammation without stones 2
• CT findings may include gallbladder wall thickening, pericholecystic inflammation, and adjacent liver parenchymal hyperemia, though CT has limitations in detecting all features without IV contrast 2
• Ultrasound is typically the first-line imaging modality for suspected biliary disease, with CT being used as a second-line option when ultrasound is equivocal 2

Treatment Approach for Acalculous Cholecystitis

Medical Management (Including Rifaximin)

• Rifaximin may be prescribed because:

  • It's a non-absorbable antibiotic that concentrates in the biliary system 3
  • It targets bacterial overgrowth that may contribute to gallbladder inflammation 3
  • It has anti-inflammatory properties that may help reduce gallbladder inflammation 3

• Medical management is often attempted first in acalculous cholecystitis, particularly in patients who are poor surgical candidates 4

Surgical vs. Non-surgical Management

• Cholecystectomy is traditionally considered the definitive treatment for acalculous cholecystitis 3, 4
• However, non-surgical management may be appropriate in selected patients 5, 6
• Percutaneous cholecystostomy (gallbladder drainage) is an alternative for patients who are poor surgical candidates 6, 4
• Recurrence rates after non-surgical treatment are significantly lower in acalculous cholecystitis (2.7%) compared to calculous cholecystitis (23.2%) 5

Risk Factors and Complications

• Acalculous cholecystitis is often associated with:

  • Critical illness 3, 6
  • Advanced age 5
  • Cerebrovascular disease 5
  • Prolonged fasting or total parenteral nutrition 3
  • Chemotherapy or immunosuppression 7

• Higher incidence of gangrenous cholecystitis is observed in acalculous cholecystitis (31.2%) compared to calculous cholecystitis (5.6%) 5

Diagnostic Challenges

• Clinical findings of right upper quadrant pain, fever, leukocytosis, and abnormal liver tests are not specific for acalculous cholecystitis 3
• Diagnosis is particularly challenging in critically ill patients, where gallbladder abnormalities are common even without acute cholecystitis 2
• Sequential imaging may be necessary for accurate diagnosis 3

Treatment Outcomes

• Mortality rates are higher in acalculous cholecystitis compared to calculous cholecystitis (45.2% vs. 21.2% at 30 days) 6
• Early diagnosis and intervention are crucial to improve outcomes 3
• Percutaneous cholecystostomy may be definitive therapy for acalculous cholecystitis without need for subsequent cholecystectomy 4

While rifaximin is not mentioned specifically in guidelines for acalculous cholecystitis, your doctor likely prescribed it to target bacterial overgrowth and reduce inflammation in your gallbladder based on your specific clinical presentation and CT findings.