Abdominal Ultrasound is the Most Appropriate Initial Diagnostic Imaging
For a patient presenting with recurrent right upper quadrant pain, jaundice, and elevated liver function tests, abdominal ultrasound should be performed first as the initial imaging modality, followed by MRCP if ultrasound is negative or equivocal. 1
Algorithmic Approach to This Clinical Presentation
Step 1: Initial Imaging with Ultrasound
The American College of Radiology explicitly recommends right upper quadrant ultrasound as the first-line imaging modality for patients with jaundice and suspected biliary obstruction, with specificities ranging between 71-97% for confirming or excluding mechanical obstruction. 1
Ultrasound has 96% accuracy for detecting gallstones and can identify critical findings including biliary dilatation, gallbladder wall thickening, pericholecystic fluid, and the presence of stones—all essential for determining the cause of jaundice and elevated LFTs. 1, 2
Ultrasound is superior to CT as initial imaging because it provides higher sensitivity for gallstones, involves no radiation exposure, has lower cost, and delivers faster results. 2
The combination of jaundice and elevated LFTs suggests biliary obstruction or cholestasis, and ultrasound can detect biliary dilatation—the critical first step in determining whether obstruction is present. 1
Step 2: Proceed to MRCP Based on Ultrasound Findings
If ultrasound demonstrates gallstones with a dilated common bile duct, or if ultrasound is negative/equivocal but clinical suspicion remains high, proceed directly to MRCP to evaluate the cause and level of biliary obstruction. 1
MRCP is the preferred advanced imaging modality over CT for suspected biliary sources of RUQ pain, with sensitivity of 85-100%, specificity of 90%, and accuracy of 89-90% for detecting choledocholithiasis. 1
MRCP excels at visualizing the common bile duct and cystic duct better than ultrasound, and can identify the level and cause of biliary obstruction (stones, strictures, masses, lymph nodes) with accuracy of 91-100%. 1
Elevated LFTs indicate biliary obstruction or cholestasis, which requires anatomic visualization of the bile ducts—something MRCP provides comprehensively. 1
Step 3: When to Consider CT Instead
CT with IV contrast should only be considered if the patient is critically ill, has peritoneal signs, or there is suspicion of complications beyond simple biliary obstruction (perforation, abscess, hemorrhage). 1
CT has lower sensitivity (~75%) for gallstone detection because up to 80% of gallstones are noncalcified and may be isodense to bile, making it inferior to ultrasound for initial evaluation. 2
The American College of Radiology states there is limited evidence for the utility of CT in detecting the cause of jaundice, and recommends starting with ultrasound for all patients with suspected gallstones or RUQ pain. 2
Critical Clinical Caveats
Do not skip ultrasound and proceed directly to MRCP or CT unless the patient is too unstable for ultrasound. The algorithmic approach of ultrasound first, then MRCP if needed, is the evidence-based standard. 1, 3
Do not order CT as first-line imaging for this presentation—it exposes patients to unnecessary radiation when ultrasound is more appropriate and diagnostic. 3
Ultrasound is the first line of imaging in patients with signs and symptoms of hepatic, gallbladder, or biliary disease, and patient triage or additional imaging decisions should be based on ultrasound findings. 4, 5
In patients with elevated alkaline phosphatase and normal ultrasound, MRCP should still be strongly considered as ALP elevation is an independent positive predictor for abnormal MRCP findings. 6