What are the indications for a hepatobiliary-pancreas (HBP) ultrasound in patients with symptoms such as abdominal pain, jaundice, or unexplained weight loss, particularly in those with a history of liver disease, pancreatitis, or gallstones, and in older adults or individuals with a history of heavy alcohol use?

Indications for Hepatobiliary-Pancreas Ultrasound

Ultrasound is the mandatory first-line imaging test for evaluating suspected hepatobiliary-pancreatic disease, particularly when patients present with jaundice, right upper quadrant pain, or unexplained cholestasis. 1, 2

Primary Clinical Indications

Jaundice Evaluation

• Ultrasound is the initial imaging test of choice for all patients presenting with jaundice, as it confirms or excludes biliary obstruction with specificities of 71-97% and detects biliary ductal dilatation with sensitivity ranging from 32-100%. 2
• The critical first step is determining whether mechanical obstruction is present versus hepatocellular disease. 2
• Ultrasound is mandatory to differentiate intrahepatic from extrahepatic cholestasis in adults with chronic cholestasis. 1

Right Upper Quadrant Pain and Suspected Gallstone Disease

• Trans-abdominal ultrasound is the recommended first-line investigation for patients with suspected gallstones, detecting gallstones with 96% accuracy and assessing for acute cholecystitis. 2, 3
• Ultrasound should be performed alongside liver biochemical tests (ALT, AST, bilirubin, alkaline phosphatase, GGT) as the initial diagnostic workup. 3
• The American College of Radiology designates ultrasound as the initial imaging modality due to its non-invasive nature, lack of radiation exposure, relatively low cost, portability, and rapid availability of results. 3

Acute Pancreatitis

• Abdominal ultrasonography should be obtained at admission for all patients with acute pancreatitis to screen for cholelithiasis or choledocholithiasis, as gallstones are causal in up to 50% of acute pancreatitis cases. 1
• If initial ultrasound is inadequate or suspicion of gallstone pancreatitis persists, repeat ultrasonography after recovery should be performed. 1

Unexplained Weight Loss and Suspected Malignancy

• Ultrasound provides rapid morphologic evaluation of liver parenchyma, detecting cirrhosis with sensitivity of 65-95% and positive predictive value of 98%. 2
• In patients older than 40 years with unexplained pancreatitis, ultrasound serves as the initial screening test before proceeding to CT or EUS to evaluate for underlying pancreatic malignancy. 1
• Ultrasound can identify focal liver masses and screen the pancreas, though sensitivity decreases for body and tail lesions. 1

Suspected Cholangitis or Biliary Obstruction

• Ultrasound accurately identifies dilated bile ducts and can visualize common bile duct stones, which is a very strong predictor of choledocholithiasis. 3
• A palpable gallbladder with jaundice on ultrasound (Courvoisier's sign) suggests malignancy in 87% of cases and warrants expedited further imaging. 2

Special Populations

Patients with Liver Disease History

• Ultrasound is the first-line imaging procedure for patients with known or suspected chronic liver disease presenting with new symptoms. 1
• It detects cirrhosis, portal hypertension, and ascites effectively. 2

Heavy Alcohol Users and Chronic Pancreatitis

• Ultrasound is indicated for screening hepatobiliary complications in patients with chronic alcohol use and recurrent pancreatitis. 4
• It can identify pancreatic abnormalities, though technical difficulties with bowel gas compromise interpretation in 20-25% of cases. 1

Older Adults with New-Onset Diabetes

• Pancreatic cancer should be considered in patients with adult-onset diabetes who have no predisposing features or family history, and ultrasound serves as the initial screening modality. 1

Critical Clinical Algorithm

Step 1: Perform abdominal ultrasound to:

• Determine presence or absence of biliary ductal dilatation 2
• Identify gallstones or gallbladder pathology 2, 3
• Assess liver parenchyma for cirrhosis or masses 2
• Evaluate for ascites or portal hypertension 2

Step 2: If ultrasound shows biliary obstruction:

• Proceed to MRCP or CT to identify the level and cause of obstruction 2
• Consider ERCP if therapeutic intervention is needed 2

Step 3: If ultrasound is negative or inconclusive:

• MRCP becomes valuable for detecting subtle pathology 2
• Consider additional laboratory testing for hepatocellular disease 2

Important Caveats

• Do not skip ultrasound and proceed directly to MRCP, as this wastes resources and delays diagnosis in straightforward cases. 2
• Normal ultrasound and liver function tests do not preclude further investigation if clinical suspicion remains high. 1, 3
• Ultrasound may miss small distal common bile duct stones, so if clinical suspicion remains high despite negative ultrasound, proceed to MRCP or endoscopic ultrasound. 2
• Technical limitations include reduced sensitivity for pancreatic body and tail lesions, and interpretation may be compromised by bowel gas in 20-25% of patients. 1
• Always apply color Doppler ultrasonography to any unclear, bull's eye-like lesion to avoid missing vascular abnormalities such as pseudoaneurysms that can mimic tumors. 5