Author: Spencer Lang, MD (EM Resident Physician, PGY-3, NUEM) // Edited by: Grant Scott, MD // Expert Commentary: Elizabeth Dearing, MD
Citation: [Peer-Reviewed, Web Publication] Lang S, Scott G (2017, February 7). Ultrasound In Cholangitis [NUEM Blog. Expert Commentary By Dearing E]. Retrieved from http://www.nuemblog.com/blog/ultrasound-cholangitis
The Case
An elderly male presented to the emergency department (ED) with hypotension and abdominal pain. His history was significant for end-stage renal disease. His dialysis session had been stopped early due to a blood pressure of 80/45 about halfway through his cycle and he was found to be febrile and transferred to the ED.
His only complaint was abdominal pain, localized to the epigastrium and right upper quadrant which started the prior night after eating dinner. He had known gallstones and he thought the pain was a “gallbladder attack” similar to his frequent biliary colic. His physical exam showed a jaundiced obese male, in no acute distress who was alert and oriented x 3 with a normal mental status. He had mild right upper quadrant (RUQ) tenderness and a markedly positive Murphy’s sign.
Given his history of cholelithiasis, a bedside ultrasound was performed to assess his right upper quadrant. Here’s what was seen:
What is the diagnosis?
Highlights of using Point Of Care Ultrasound (POCUS) in evaluation of the biliary tree.
Basic Technique
Figure 1: Probe placement. Image from Cosby, Karen S.; Kendall, John L., Practical Guide to Emergency Ultrasound, 1st Edition, Copyright (c) 2006 Lippincott Williams & Wilkins.
Just as with all RUQ imaging, start with the patient supine, and the abdominal probe in either the subcostal or flank position and use the liver as an acoustic window. If images are suboptimal, try having the patient roll on their left side slightly. For some patients images are best as the patient holds deep inspiration.
Common Bile Duct (CBD) – What is Normal?
Figure 2: Short axis diagram, CBD and hepatic artery forming ears of the Mickey Mouse sign with portal vein as Mickey’s head.
The CBD can be seen well in one of two ultrasound views. When captured in short axis at the portal triad it is typically Mickey’s right ear in the Mickey mouse sign (Mickey’s head is the portal vein and his left ear is the hepatic artery, see Figure 2). If you are ever unsure which ear is which structure, use color Doppler, the artery has a pulse. The CBD can also be seen in long axis, where it is perpendicular and just anterior to the portal vein.
For adult patients, normal diameter starts at ~4 mm but increases with age. As a rule of thumb, for every decade over 40, add 1 mm. It is also notable that diameter increases after cholecystectomy (up to 10 mm) [4].
When to Suspect Choledocholithiasis
Using the same views as above, the CBD will often have a dilated appearance. Mickey will have a swollen right ear in short axis and in long axis the normally thin duct will appear similar in size to the portal vein, known as the double shotgun sign. However, in the right clinical picture don’t exclude the diagnosis on the basis of normal measurements as in one retrospective series, 28% of people diagnosed with choledocholithiasis had a duct < 6 mm in size.
When you see a dilated duct it is critical to assess the rest of the biliary tree and clinical picture (labs). It is rare (<1% of cases) to have isolated CBD dilation as the only finding in true choledocholithiasis. The vast majority will have some liver function abnormalities or signs of cholecystitis on US, so assess the gallbladder for signs of cholecystitis – such as wall thickening, pericholecystic fluid, and a sonographic Murphy’s sign [1].
How Good is POCUS for the Right Upper Quadrant?
While formal RUQ US has sensitivity up to 91% to diagnose obstructive biliary disease, bedside US by ED physicians is less sensitive to identify CBD dilatation – anywhere from 10-80% from various studies, and is operator dependent. So depending on your level of expertise it can be very helpful to rapidly narrow down the differential, but if you have high clinical suspicion for obstruction or other pathology and don’t see it at the bedside, obtain a formal RUQ US if possible. However, studies have shown that physicians in the emergency department have fantastic sensitivity for finding gallstones, which can only strengthen your suspicion for cholangitis [3].
Case Imaging Interpretation and Wrap Up
Note multiple shadowing stones within the gallbladder (red arrows).
A significantly dilated CBD (white line) is appreciated here. Note the culprit obstructing gallstone is seen to the right of the image (red arrow).
As you can see, in this case the CBD was dilated to ~ 1.3 cm, or 13 mm. Further, you can see a large stone stuck distally in the CBD, causing the obstruction. This quick ultrasound and the patient’s clinical picture with jaundice, RUQ pain, fever, and hypotension led to the rapid diagnosis of acute cholangitis due to choledocholithiasis, antibiotics were started and GI was consulted for emergent ERCP for source control.
Expert Commentary
Dear Spencer,
Great utilization of bedside ultrasound to help efficiently diagnose a sick patient! Biliary ultrasound can be difficult, especially for beginners. This case shows that if you work to improve your skills you can get consultants involved early instead of waiting a significantly longer time, sometimes hours, to get a comprehensive radiology-performed RUQ ultrasound. Source control is important and, in addition to antibiotics, these patients may need emergent intervention with GI and/or surgery so those minutes or hours are important.
Technique
I agree that you should generally start just below the costal margin to the right of midline and slide towards the axilla. You may see a portion of the gallbladder and should then make smaller movements (e.g. rotate, fan) to bring the gallbladder into view. If you cannot find the gallbladder or have an inadequate view, have the patient roll onto their left side and/or take a deep breath and hold it to improve the image. If this is not successful you can move laterally to the patient’s anterior to mid axillary line (around the position for FAST exam) and try to image the gallbladder from the side. You could also try to use the phased-array and image through the lower rib spaces.
You should also evaluate for other signs of cholecystitis including gallbladder wall thickening (greater than 3 mm when measuring anterior gallbladder wall), pericholecystic fluid and sonographic Murphy’s sign. There are other reasons for gallbladder wall thickening such as decompressed gallbladder after eating, heart failure, etc so keep the clinical context in mind. For sonographic Murphy’s, center the gallbladder on the screen and use the probe to apply direct pressure to the gallbladder and assess for tenderness. You should then apply pressure over other areas of RUQ that do not include gallbladder in image. A sonographic Murphy’s is positive if the patient is maximally tender when pressure is applied directly over the imaged gallbladder.
The Dreaded CBD
The common bile duct can be difficult to find and evaluate and is often a frustration for new learners. Depending on the location of the gallbladder in the fossa you may need to rotate the probe marker towards the patient’s right or more vertical or even slightly angled toward the left to get the longitudinal view of the gallbladder with the “Mickey mouse” view. Because of this, the best way to ensure you are visualizing the CBD (normally lateral to the artery) and not the hepatic artery is to use color Doppler. Additionally, use color in the longitudinal view because both the CBD and hepatic artery will course along the portal vein. If you get flow in both the PV and the vessel immediately anterior, fan the probe to angle towards the CBD, which is without flow. You should measure the CBD at the largest diameter if possible which is the extra-hepatic portion and easiest to find by following the duct in the longitudinal plane. Lastly, the actual number for CBD dilation can vary in practice. ACEP’s EUS compendium notes a normal CBD of less than 3mm and adding 1mm for each decade of age. The normal value can range from 3-6mm with 6mm being more specific and 3mm being more sensitive.
Ultrasound is the best test for gallbladder pathology but can be difficult. Still, as you noted, emergency medicine physicians can perform bedside US to evaluate for gallstones with good sensitivity and the prevalence of serious gallbladder pathology with normal labs and isolated CBD dilation is very low. Additionally, Summers, et. al. showed that the test characteristics of bedside ultrasound are similar to those of radiology performed ultrasound for detection of acute cholecystitis. Will there be times that you need to get a radiology-performed ultrasound? Absolutely. Body habitus is a limiting factor especially with point-of-care machines. Surgeons and internists usually want a “formal” ultrasound with radiology interpretation. Or maybe it’s a busy shift and you are taking care of several other patients who happen to be sicker. But if you do have a minute, you may be able to expedite the RUQ pain patient’s care, disposition and narrow the diagnosis with a quick bedside ultrasound of their gallbladder. Like other procedures, you can only get better if you practice!
Elizabeth Dearing, MD
Assistant Professor; Department of Emergency Medicine; Division of Emergency Ultrasound; Vanderbilt University Medical Center
References
- Becker, B., Chin, E., Mervis, E., Anderson, C., Oshita, M., Fox, J. (2013). Emergency Biliary Sonography: Utility of Common Bile Duct Measurement in the Diagnosis of Cholecystitis and Choledocholithiasis. The Journal of Emergency Medicine, 54-60.
- Cosby, K. (2006). Practical Guide to Emergency Ultrasound. Philadelphia, PA.: Lippincott Williams & Wilkins.
- Kendall, J., Shimp, R. (2009). Performance and interpretation of focused right upper quadrant ultrasound by emergency physicians. The Journal of Emergency Medicine, 7-13.
- Kaim A, Steinke K, Frank M, Enriquez R, Kirsch E, Bongartz G, Steinbrich W. (1998). Diameter of the common bile duct in the elderly population: measurement by ultrasound. European Journal of Radiology. 8(8): 1413 .
Ultrasound E, Criteria I. ACEP Emergency Ultrasound Imaging Criteria Compendium.; 2006. Available at: http://www.acep.org/ultrasound/
Summers SM, Scruggs W, Menchine MD, et al. A Prospective Evaluation of Emergency Department Bedside Ultrasonography for the Detection of Acute Cholecystitis. Ann Emerg Med. 2010;56(2):114–122.