INDICATIONS
The hepatobiliary / gallbladder exam is most helpful in streamlining your next steps in the evaluation of a patient with upper abdominal pain.
- any upper abdominal pain
- right flank pain
- jaundice, elevated bilirubin, liver function tests or lipase
- sepsis/septic shock of unknown source
FOCUSED QUESTIONS
PRIMARY QUESTIONS
- Are there gallstones?
- Is there a sonographic Murphy’s sign?
SECONDARY QUESTIONS
- Is the anterior gallbladder wall thickened?
- Is there pericholecystic fluid?
- Is the common bile duct dilated?
PREPARATION
Normally the large curvilinear probe should be used. The lower frequency range improves resolution of deeper structures like the gallbladder.
The phased array probe can be used to scan between ribs which may provide superior imaging.
VIEWS
The subcostal approach is usually successful. Place the probe in a sagittal midline orientation with probe marker toward the patient’s head, sweeping to the right along the inferior costal margin, looking for a pear shaped hypoechoic structure with thin hyperechoic walls. When you find the gallbladder, sweep through in short and long axis.
LONG AXIS VIEW OF GALLBLADDER
SHORT AXIS VIEW OF GALLBLADDER
FINDING THE GALLBLADDER
If you cannot identify the gallbladder using the medial to lateral subcostal sweep, you can try one or more of the following:
- Ask patient to take and hold a deep breath. This should move diaphragm and liver down and bring the gallbladder into view.
- Image from the flank (like the FAST RUQ view). If bowel gas is interfering with the anterior view, this may work better.
- Image between ribs. You can angle the large curvilinear probe to match the curvature of the ribs or use the phased array probe which has a smaller footprint.
PATHOLOGY
GALLSTONES
Gallstones are strongly echogenic. Large stones will have a pronounced echocgenic anterior curvature. Smaller stones be layered, not obviously round structures. All stones should have posterior acoustic shadowing. Stones will be mobile, while gallbladder polyps will be fixed. You can scan the patient supine and then have them turn on their side to assess stone mobility.
WES (WALL-ECHO-SHADOW) SIGN
Gallstones within a contracted gallbladder will appear as a WES sign. This is when the anterior echogenic gallbladder wall is seen, with the echo of the gallstone(s) behind it and shadowing behind these structures.
BILIARY SLUDGE
Before gallstones are formed, bilary sludge may be seen. Sludge is liquid and should layer but not shadow.
CHOLECYSTITIS
When gallstones are seen, complications including biliary colic, cholecystitis, choledocholithiasis and cholangitis may be the cause of the patient’s ED presentation.
SONOGRAPHIC MURPHY’S SIGN
The most significant test for cholecystitis in the appropriate patient with gallstones on ultrasound is the sonographic murphy’s sign. (Huang 2023) Sonographic Murphy’s is positive if the patient is tender when the gallbladder is compressed with the ultrasound probe (sonopalpation) but no other part of the abdomen is tender.
There is evidence that analgesia given prior to evaluation does not compromise the physicial exam murphy’s sign and the same has been found regarding the sonographic murphy’s sign. (Noble 2010)
One caveat to this is that the absence of sonographic murphy’s with an ultrasound that has the appearance of cholecystitis may represent acute gangrenous cholecystitis. (Simeone 1989)
GALLBLADDER WALL THICKENING
In cholecystitis the gallbladder walls become inflamed and thickened. Measure the anterior wall which is more reliable due to proximity to the transducer with fewer intervening structures. Gallbladder wall thickening > 3 mm is the commonly accepted pathologic cutoff.
Confounders — Both gallbladder wall thickening and pericholecystic fluid may be seen in fluid retentive states (chf, ascites, etc…). Wall thickinening is expected when the gallbladder is contracted, as in post-prandial patients.
PERICHOLECYSTIC FLUID
COMMON BILE DUCT
The utility of CBD measurements in ED point of care gallbladder studies is limited (Lahham 2017). Lahham finds that in the absence of abnormal laboratory values, sonographic murphy’s or secondary signs of gallbladder inflammation, obtaining a CBD measurement is unlikely to contribute to the evaluation of this patient population. However, when labs (i.e elevated direct bilirubin and/or lipase) are abnormal and raise concern for an obstructive process (common duct stone, pancreatic or choledochal mass) evaluation of the common duct may be more helpful.
Start with a long axis view of the gallbladder and portal triad.
Zoom in on the portal triad, looking for the “Mickey Mouse” sign. The large portal vein will be below the common bile duct on the left and the hepatic artery on the right.
The anatomical relationship between the portal triad vessels is not always preserved, so using doppler signal to identify the hepatic artery (flow) and common bile dut (no flow) will be helpful.
Measure the common bile duct in long axis if possible and from inner edge to inner edge. A common bile duct above 3mm is commonly accepted as abnormal.
