Background
-Biliary disease is the 3rd most common cause of acute abdominal pain in the ED.
-Bedside ultrasonography in the Emergency Department has been shown to be effective in detecting choledocholithiasis and cholecystitis, as well as reducing patient length of stay with ED providers have a Specificity 96% and Sensitivity 88% using bedside ultrasound (US).
Common Indications
-Right upper quadrant pain
-Fever
-Nausea
-Jaundice
-Vomiting
US Findings of Cholecystitis
-Stone(s)
-Wall thickening (Defined as > 3mm and can be measured in the short or long axis and should be measured at the thickest point along the wall)
-Pericholecystic fluid
-Sonographic Murphy (find fundus with US, ask pt to deeply inhale, if that elicit pain it is considered a positive finding
Anatomy
Technique
Probe of choice is the curvilinear probe. With the probe marker cranial (longitudinal orientation) sweep the probe along the subcostal margin as shown to the right
Imaging may be improved by asking the patient to inhale deeply or to turn onto their left side in a left lateral decubitus position.
X minus 7
This approach is used to visualize the gallbladder through an intercostal window, it is usually used if US examination via the curvilinear probe elicits unbearable pain. This allows the operator to use the smaller phase-array probe instead to reduce pain.
The probe is placed approximately seven centimeters lateral to the xiphoid process, with the probe oriented to maximize the window between rib spaces and if the gallbladder is not identified, continue to move the probe laterally, while fanning through the liver parenchyma.
Gallbladder Wall Thickening
Be careful of false positives including congestive states, ascites, and in the setting of a contracted gallbladder. It is important to interpret US findings with the clinical context.
Example is shown below:
Gallstones
Gallstones appear as hyperechoic structures in the gallbladder that also demonstrate shadowing
Examples are shown below:
Gallstone in gallbladder neck
2 gallstones: 1 in gallbladder fundus and the another in the neck
Pericholecystic fluid
Appear as hypoechoic free fluid surrounding the gallbladder, often visualized in the space between the gallbladder and liver
Examples are shown below:
Gallstone and pericholecystic fluid
Common Bile Duct (CBD) distension
-Normal CBD < 6 mm (add 1mm per decade of life over the age of 60).
-Locate portal triad via longitudinal, (portal vein, CBD, and hepatic artery), CBD is usually left of vein, and hepatic artery on the right (but can be reversed).
-Tips: Use color doppler, follow the main lobar fissure to the portal triad, and repositioning to optimize image
Examples are shown below:
Can put flow to help with identification, left is portal vein, right is hepatic artery
Contracted Gallbladder
A contracted gallbladder may be difficult to visualize and have walls that appear thickened with a three-layer appearance. If three layers are visible, this is not considered pathologic thickening
Example is shown below:
Wall-Echo-Shadow sign (WES sign)
Gallbladder is contracted around a stone(s). Shadowing from the stone(s) obscures the gallbladder posterior to them. As a result you see, anterior gallbladder wall, followed by the hyperechoic stone(s), and then the stone(s) shadow.
Example is shown below:
Conclusions
Takeaway #1: US Findings of Cholecystitis
-Stone(s)
-Wall thickening
-Pericholecystic fluid
-Sonographic Murphy
Takeaway #2: Use the X-7 approach if the patient cannot tolerate pain. Can optimize images if patient is on left lateral decubitus position and/or during deep inspiration
Takeaway #3: Wall thickening is defined as > 3mm and abnormal CBD > 6 mm (add 1mm per decade of life over the age of 60)
References:
Kendall JL, Shimp RJ. Performance and interpretation of focused right upper quadrant ultrasound by emergency physicians. J Emerg. Med. 2001; 21(1):7-13.
Lahham, S., B. A. Becker, A. Gari, S. Bunch, M. Alvarado, C. L. Anderson, E. Viquez, S. C. Spann and J. C. Fox (2018). “Utility of common bile duct measurement in ED point of care ultrasound: A prospective study.” Am J Emerg Med 36(6): 962-966. PMID: 29162442
Miettinen, P., P. Pasanen, J. Lahtinen and E. Alhava (1996). “Acute abdominal pain in adults.” Ann Chir Gynaecol 85(1): 5-9. PMID: 8739926