What is the appropriate workup for cholelithiasis (gallstones)?

Workup of Cholelithiasis

Ultrasound is the first-line imaging test for suspected cholelithiasis with 96% accuracy for detecting gallstones, and should be performed in all patients with right upper quadrant pain to assess for gallstones and evaluate the biliary tree. 1

Initial Diagnostic Approach

Clinical Presentation

• Right upper quadrant pain (classic presentation)
• Referred pain to right supraclavicular region/shoulder
• Nausea and vomiting
• Positive Murphy's sign (tenderness on palpation of right upper quadrant during inspiration)
• Fever and elevated WBC may indicate complications like cholecystitis

Laboratory Testing

• Complete blood count
• Liver function tests (ALT, AST, bilirubin, ALP, GGT)
  • These tests help assess risk for common bile duct stones 1
  • Sustained elevation of ALP correlates significantly with choledocholithiasis 1

Imaging Algorithm

Step 1: Abdominal Ultrasound

• Gold standard initial test for cholelithiasis diagnosis 2
• Advantages:
  • High accuracy (96%) for gallstone detection 1
  • Can differentiate cholelithiasis from gallbladder sludge, polyps, or masses
  • Non-invasive, portable, relatively inexpensive
  • No radiation exposure
  • Can evaluate intrahepatic and extrahepatic bile ducts
• Findings suggestive of cholelithiasis:
  • Echogenic foci with acoustic shadowing in the gallbladder
  • Gallbladder wall thickening (>3mm) may indicate cholecystitis
  • Pericholecystic fluid (suggests inflammation)
  • Sonographic Murphy sign (although specificity is limited) 1

Step 2: Further Imaging Based on Ultrasound Results

If Ultrasound is Positive for Gallstones:

• No further imaging needed if uncomplicated cholelithiasis
• If complications suspected (cholecystitis, choledocholithiasis):
  • Assess risk for common bile duct stones using modified ASGE criteria 1:
    • Very strong predictors: CBD stone on ultrasound, cholangitis, bilirubin >4 mg/dL
    • Strong predictors: Dilated CBD on ultrasound (>6mm with gallbladder in situ), bilirubin 1.8-4 mg/dL
    • Moderate predictors: Abnormal liver function tests, age >55, clinical gallstone pancreatitis

If High Risk for CBD Stones:

• Proceed directly to ERCP if CBD stone visualized on ultrasound 1
• Otherwise, consider MRCP, EUS, or intraoperative cholangiography 1

If Moderate Risk for CBD Stones:

• MRCP (sensitivity 85-100%, specificity 90%) 1, 3
• Endoscopic ultrasound (sensitivity 95%, specificity 97%) 1
• Choice depends on local expertise and availability

If Ultrasound is Negative or Equivocal but Suspicion Remains:

• CT abdomen with IV contrast
  • More sensitive than ultrasound for acute cholecystitis (92% vs 79%) 4
  • Can identify complications like emphysematous or gangrenous cholecystitis
  • Less sensitive for gallstone detection (75% sensitivity) 1
• MRI abdomen with MRCP
  • Excellent for detecting choledocholithiasis
  • Superior to CT for biliary evaluation 1
  • Particularly useful when ultrasound shows dilated bile ducts 1

Management Considerations

Asymptomatic Cholelithiasis

• Generally managed with observation alone 5
• Only 10-25% of asymptomatic cases progress to symptomatic disease 5

Symptomatic Cholelithiasis

• Referral to surgeon and/or gastroenterologist within 2 weeks of initial presentation regardless of symptom severity 2
• Laparoscopic cholecystectomy for recurrent or severe symptoms
• Lifestyle and dietary modifications with possible gallstone dissolution agents for single symptomatic episode 2

Potential Pitfalls

• False positive ultrasound results (3.9%) - consider repeating suboptimal examinations 6
• False negative ultrasound results (2.3%) - may occur with small stones or thick-walled gallbladder 6
• Ultrasound limitations in critically ill patients where gallbladder abnormalities are common without acute cholecystitis 1
• CT has limited sensitivity for gallstones but better sensitivity for complications 4

Special Considerations

• MRCP may have diminished sensitivity for stones <4mm in size 3
• Cholescintigraphy (HIDA scan) has higher sensitivity (97%) and specificity (90%) for acute cholecystitis but is not first-line for simple cholelithiasis 1
• Consider CT in elderly patients or those with atypical presentations 1