What is the initial workup for a patient suspected of having gallstones?

Initial Workup for Suspected Gallstones

The initial diagnostic workup for patients suspected of having gallstones should include liver biochemical tests and abdominal ultrasound as the first-line investigations. 1, 2

Initial Laboratory Tests

• Complete liver biochemistry panel including:

  • Total and direct bilirubin
  • Alanine aminotransferase (ALT)
  • Aspartate aminotransferase (AST)
  • Alkaline phosphatase (ALP)
  • Gamma-glutamyl transferase (GGT) 1, 2

• Complete blood count to assess for signs of infection or inflammation 3

• Serum amylase and lipase to rule out pancreatic involvement or pancreatitis, with lipase being preferred due to greater specificity 2

• Coagulation studies (INR/PT), especially if endoscopic or surgical intervention might be considered 1, 2

Imaging Studies

• Ultrasound (US) of the abdomen is the first-line imaging modality for suspected gallstones with reported accuracy of 96% for detection of gallstones 4, 1
  • Advantages: non-invasive, no radiation exposure, relatively inexpensive, portable, and results generally available quickly 4
  • Can identify gallstones, gallbladder wall thickening, pericholecystic fluid, and gallbladder sludge 4
  • Can also evaluate intrahepatic and extrahepatic bile ducts for dilation 4

Risk Stratification for Common Bile Duct Stones

Based on initial findings, patients should be stratified for risk of common bile duct stones 1:

• Very strong predictors:

  • Visualization of common bile duct stone on ultrasound 1

• Strong predictors:

  • Common bile duct dilation on ultrasound
  • Bilirubin level >4 mg/dl 1, 2

• Moderate predictors:

  • Abnormal liver function tests
  • Age >55 years
  • Clinical gallstone pancreatitis 1

Further Imaging Based on Initial Findings

If ultrasound findings are equivocal or additional information is needed:

• For suspected acute cholecystitis with equivocal US:

  • CT scan can be considered as subsequent imaging to identify complications and rule out other etiologies 4
  • Hepatobiliary iminodiacetic acid (HIDA) scan is considered the gold standard for diagnosing acute cholecystitis 4, 5

• For suspected common bile duct stones (choledocholithiasis):

  • Magnetic resonance cholangiopancreatography (MRCP) is an accurate, non-invasive diagnostic test 1, 5
  • Endoscopic ultrasound (EUS) has high sensitivity (89.5%) and specificity (96.5%) for detecting common bile duct stones 6
  • Endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard but is more invasive and should be reserved for therapeutic purposes 6

Special Considerations

• Normal liver biochemical tests have a high negative predictive value (97%) for common bile duct stones, but the positive predictive value of abnormal results is only about 15% 1, 2

• In patients with negative initial ultrasound but persistent symptoms, consider repeat testing or additional imaging 2

• For patients with moderate risk for choledocholithiasis, additional investigations such as MRCP, EUS, intraoperative cholangiography, or laparoscopic ultrasound should be considered 1

• In pregnant patients with suspected gallstones, ultrasound or MRI can be considered as the initial diagnostic imaging modality to avoid radiation exposure 4

• Ultrasound results may be limited by abdominal tenderness and patient obesity 4