Tests
1st tests to order
abdominal ultrasound
Test
Abdominal ultrasound is the initial imaging test of choice used to detect gallbladder stones or bile duct dilation caused by biliary obstruction.[1][71][72][79][80] If the history and exam, laboratory test results, and ultrasound findings are in agreement, no further imaging is needed.[81]
If available, targeted point of care ultrasound (POCUS), performed at the bedside, can help to diagnose gallstones and expedite subsequent clinical decision making.[71][72][82]
Abdominal ultrasound, however, has low sensitivity for choledocholithiasis, despite being accurate in identifying any associated bile duct dilation.[84][85]
For acute calculous cholecystitis, abdominal ultrasound has high sensitivity for detecting stones, as well as distension of the gallbladder lumen, plus any inflammatory features, gallbladder wall thickening, pericholecystic fluid, and/or a positive radiologic Murphy's sign.[84][Figure caption and citation for the preceding image starts]: Ultrasound of acute cholecystitis and presence of gallstones: the arrow points to a gallstone in the fundus of the gallbladder with its echogenic shadow belowCourtesy of Charles Bellows and W. Scott Helton; used with permission [Citation ends].
[Figure caption and citation for the preceding image starts]: Gallbladder ultrasound demonstrating cholelithiasis with characteristic shadowingCourtesy of Kuojen Tsao; used with permission [Citation ends].
Result
cholelithiasis: stones in the gallbladder
choledocholithiasis: stones in the bile duct with or without bile duct dilation
serum liver function tests
Test
For biliary pain, with or without jaundice. Elevated alkaline phosphatase suggests obstruction of the cystic or bile duct. Passage of a common bile duct stone may be revealed by a transiently elevated alanine aminotransferase, even before the rise in alkaline phosphatase.[76]
Result
uncomplicated cholelithiasis: normal
choledocholithiasis: elevated alkaline phosphatase, elevated bilirubin
CBC
serum lipase or amylase
Test
For severe sudden-onset mid-epigastric or left upper quadrant abdominal pain, with or without radiation to the back, to exclude pancreatitis. Serum lipase is the preferred test; lipase levels remain elevated for longer (up to 14 days after symptom onset vs. 5 days for amylase), providing a higher likelihood of picking up a diagnosis of acute pancreatitis in patients with a delayed presentation.[77][78]
Result
usually normal in uncomplicated cholelithiasis
elevated (>3 times upper limit of normal) in acute pancreatitis
Tests to consider
magnetic resonance cholangiopancreatography (MRCP)
Test
For suspected choledocholithiasis that is not confirmed by abdominal ultrasound.
MRCP has a sensitivity of 95% and specificity of 97% for the detection of bile duct stones.[75][86] However, it has a reduced sensitivity (65%) for the detection of small (<5 mm) biliary stones.[86][87]
Result
stones in gallbladder or bile duct
endoscopic ultrasound scan (EUS)
Test
For suspected choledocholithiasis (e.g., positive symptoms ± blood tests) but negative abdominal ultrasound. Can be used to evaluate patients who are unable to undergo an MRCP (e.g., those with implanted devices). Depending on local expertise, EUS may be more accurate than MRCP, and can be useful for detecting patients at low to moderate risk of bile duct stones (negative ultrasound imaging but positive symptoms and/or blood tests) who would benefit from a subsequent endoscopic retrograde cholangiopancreatography.[1][20][88][89][90][91][92][93][94][95]
EUS is not suitable for patients who have had gastrointestinal bypass procedures.[20]
Result
stones in gallbladder or bile duct
endoscopic retrograde cholangiopancreatography (ERCP)
Test
If initial imaging is negative but clinical features and/or blood tests are suggestive of choledocholithiasis and the patient is at high risk of complications (e.g., acute cholangitis, acute pancreatitis), ERCP is recommended. ERCP can be both diagnostic and therapeutic, enabling removal of any obstructing stones to provide biliary drainage.[94]
[ 
]
[Evidence B]
Result
stones in gallbladder or bile duct
abdominal CT scan
Test
If abdominal ultrasound is unremarkable, CT abdomen with intravenous contrast can be used to investigate alternate diagnoses such as suspected acute (ascending) cholangitis or gallstone pancreatitis, and to identify potential complications of acute cholecystitis (e.g., emphysema of the gallbladder wall, abscess formation, perforation).[1][79][95]
Result
may be normal or show stones in the gallbladder, and possibly in the bile or pancreatic ducts
may show acute (ascending) cholangitis: bile duct dilation with choledocholithiasis
may show acute pancreatitis: diffuse or segmental enlargement of the pancreas
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