What is the most appropriate diagnostic imaging for a patient presenting with recurrent right upper quadrant (RUQ) pain, jaundice, RUQ tenderness, elevated liver function tests (LFT) and hyperbilirubinemia?

Abdominal Ultrasound is the Most Appropriate Initial Diagnostic Imaging

For a patient presenting with recurrent right upper quadrant pain, jaundice, RUQ tenderness, and elevated liver function tests with hyperbilirubinemia, abdominal ultrasound is the most appropriate initial diagnostic imaging modality. 1, 2

Rationale for Ultrasound as First-Line Imaging

The American College of Radiology explicitly recommends ultrasound as the initial evaluation for patients presenting with jaundice and suspected biliary obstruction, with specificities ranging between 71% to 97% for confirming or excluding mechanical obstruction. 1, 3

Key diagnostic capabilities of ultrasound in this clinical scenario include:

• Detection of biliary dilatation, which is the critical first step in determining whether obstruction is present and guides subsequent management 3
• Identification of gallstones with 96% accuracy, which are the most common cause of obstructive jaundice 2
• Assessment of gallbladder wall thickening, pericholecystic fluid, and other signs of acute cholecystitis 1, 2
• Evaluation of intrahepatic and extrahepatic bile ducts to determine the level of obstruction 1, 4
• Detection of alternative diagnoses such as cirrhosis (sensitivity 65-95%, positive predictive value 98%) 1

Why Not MRCP or CT as Initial Imaging?

While MRCP has superior sensitivity (85-100%) and specificity (90%) for detecting choledocholithiasis and characterizing biliary obstruction, the American College of Radiology guidelines clearly state that ultrasound should be performed first, with MRCP reserved for cases where ultrasound is negative or equivocal. 3

CT abdomen is not recommended as first-line imaging because:

• CT has lower sensitivity (approximately 75%) for gallstone detection since up to 80% of gallstones are noncalcified and may be isodense to bile 2
• CT exposes patients to radiation without clear advantage as a first-line test 3
• CT is less sensitive than ultrasound for initial biliary evaluation 3

Clinical Algorithm for This Patient

Step 1: Perform abdominal ultrasound immediately to assess for:

• Biliary dilatation (intrahepatic and extrahepatic ducts) 1, 3
• Gallstones in the gallbladder or common bile duct 2, 4
• Gallbladder wall thickening or pericholecystic fluid 1
• Signs of cirrhosis or other hepatic parenchymal disease 1

Step 2: If ultrasound demonstrates biliary dilatation or is equivocal:

• Proceed to MRCP to comprehensively evaluate the biliary tree for stones, strictures, or obstruction 3
• MRCP can identify the level and cause of biliary obstruction with accuracy of 91-100% 3

Step 3: If the patient is critically ill or has peritoneal signs:

• Consider CT abdomen with IV contrast to evaluate for complications such as perforation, abscess, or emphysematous cholecystitis 1, 3

Important Clinical Caveats

• Ultrasound has shorter study time, is portable, lacks radiation exposure, and costs less than CT or MRI, making it ideal for initial evaluation 1, 2
• The sonographic Murphy sign has relatively low specificity for acute cholecystitis and is unreliable if the patient has received pain medication prior to imaging 1
• In critically ill patients, gallbladder abnormalities are common even in the absence of acute cholecystitis, which may limit ultrasound's diagnostic utility in this specific population 1
• If ultrasound shows a dilated common bile duct with gallstones, the patient likely has choledocholithiasis causing obstructive jaundice and may require therapeutic ERCP 3, 4