What is the workup for gallstones?

Workup for Gallstones

Begin with transabdominal ultrasound and liver function tests as your first-line diagnostic approach for suspected gallstone disease. 1, 2

Initial Diagnostic Evaluation

Clinical Presentation to Assess

• Right upper quadrant or epigastric pain (sudden onset, often postprandial) 3
• Murphy sign on physical examination (specific for acute cholecystitis) 3
• Jaundice, fever, or signs of cholangitis (indicating potential complications) 1
• History of pancreatitis (gallstones cause up to 50% of acute pancreatitis cases) 1

First-Line Laboratory Tests

• Liver function tests including bilirubin, alkaline phosphatase, ALT, AST, and GGT 1, 2
• Complete blood count 2
• Lipase or amylase (if pancreatitis suspected) 4
• Important caveat: Normal LFTs do not exclude gallstone disease or common bile duct stones (CBDS), as only 15% PPV for CBDS with abnormal LFTs 1

First-Line Imaging

• Transabdominal ultrasound is the initial imaging modality of choice 1, 2, 3
  • Sensitivity: 79% for acute cholecystitis 5, 25-63% for CBDS 4
  • Specificity: 87% for detecting cholelithiasis 5
  • Limitation: Poor visualization of distal common bile duct and operator-dependent 4

Risk Stratification for Common Bile Duct Stones

If gallstones are confirmed, immediately stratify the patient's risk for CBDS using the following criteria: 1

Very Strong Risk Factors (High Risk)

• CBDS visualized on ultrasound 1
• Ascending cholangitis (fever, jaundice, right upper quadrant pain) 1

Strong Risk Factors (Intermediate Risk)

• Common bile duct diameter >6 mm (with gallbladder in situ) 1
• Total serum bilirubin >1.8 mg/dL 1

Moderate Risk Factors (Intermediate Risk)

• Abnormal liver biochemistry (other than bilirubin) 1
• Age >55 years 1
• Clinical gallstone pancreatitis 1

Advanced Imaging Based on CBDS Risk

Low Risk (No Predictors Present)

• Consider alternative diagnosis 1
• No further biliary imaging needed unless symptoms persist 1

Intermediate Risk (Moderate Risk Factors Only)

• Obtain MRCP or endoscopic ultrasound (EUS) 1
  • MRCP: Sensitivity 93%, specificity 96% for CBDS 1
  • EUS: Sensitivity 95%, specificity 97% for CBDS 1
  • MRCP is preferred as first-line due to non-invasive nature, wide availability, and ability to image intrahepatic ducts 1, 4
  • EUS may be chosen based on local expertise, patient factors (claustrophobia, pacemakers), or need for tissue diagnosis 1

High Risk (Very Strong Risk Factors Present)

• Proceed directly to ERCP (therapeutic intent) or consider intraoperative cholangiography (IOC)/laparoscopic ultrasound (LUS) at time of surgery 1
• ERCP: Sensitivity 83%, specificity 99% 1
• IOC: Sensitivity 99%, specificity 99% 1
• Important caveat: ERCP carries 1-2% complication rate (pancreatitis, bleeding, perforation), increasing to 10% with sphincterotomy 1

Special Imaging Considerations

When CT May Be Obtained Instead

• CT is more sensitive than ultrasound for acute cholecystitis (92% vs 79% sensitivity) but less sensitive for cholelithiasis (60% vs 87%) 5
• CT is often the first test obtained in emergency settings when diagnosis is unclear 5
• Use CT when evaluating for complications (perforation, abscess) or alternative diagnoses 4

When to Use HIDA Scan

• Obtain hepatobiliary iminodiacetic acid (HIDA) scan when ultrasound is negative or equivocal but clinical suspicion for acute cholecystitis remains high 3
• Sensitivity: 84-89%, specificity: 67-79% for acute cholecystitis 1

When to Use Functional Testing

• Cholecystokinin-cholescintigraphy (CCK-CS) with gallbladder ejection fraction calculation for suspected biliary dyskinesia 2
• Abnormal if ejection fraction <38% at 60 minutes 2
• Avoid in hospitalized or acutely ill patients (high false positive rate) 2

Common Pitfalls to Avoid

• Do not rely solely on elevated LFTs to diagnose CBDS—15-50% of acute cholecystitis patients have elevated LFTs without CBDS 1
• Do not skip further imaging in intermediate-risk patients—proceeding directly to ERCP results in 30-75% unnecessary procedures 1
• Do not delay MRCP/EUS in favor of diagnostic ERCP unless patient has high-risk features requiring immediate therapeutic intervention 1, 4
• Normal ultrasound does not exclude CBDS or cholecystitis if clinical suspicion remains high 1, 2