3. Case of the month: Gallstones, dilated CBD

Case and images courtesy of Dr Micky Fiorentino (ultrasound under supervision of Dr James Dent)

Triage at 1pm:
46F, representation with recurrent RUQ pain. Known gallstones. Representing with further pain, yellow skin colour and pale stool and dark urine.

Minimally tender RUQ, Murphy’s negative

Initial blood tests:
Hb 135
WCC 3.8 x 109
Bil 91
Albumin 41
Protein 82
ALP 349
Gamma GT 524
ALT 205
AST 142
Lipase 78

A decision made to perform a point of care biliary ultrasound.

This is the longitudinal view of the gallbladder.

How would you describe the findings?

There are multiple small  (<1cm) gallstones throughout the GB fundus and neck within a layer of sludge.  Note the posterior acoustic shadowing which confirms that these are gallstones. It is important to note whether gallstones are mobile by changing patient positioning, particularly if the stones are seen in  the neck of the gallbladder because impacted gallstones in the neck of the gallbladder are the most common cause of cholecystitis.

This is the gallbladder in the transverse plane. Describe your findings.   

Again, numerous gallstones are seen. The transverse view is generally used to measure GB wall thickness, ideally in the anterior wall adjacent to the hepatic parenchyma. A GB wall >3mm is considered abnormal and suggests cholecystitis. This can be accompanied by peri-cholecystic fluid. The GB wall thickness is 2mm in this case. Fasting status is important as this can lead to false positives.

The clip shows a sweep from the fundus to the neck of the GB. At the fundus the CBD comes into view and the more proximal intrahepatic bile ducts are visible.

This is a view of her CBD. What are the pertinent findings?

A good way of differentiating the CBD from the portal vein is to use colour. The portal vein will show blood flow but not the CBD. Using the dual screen with one side showing the CBD and portal vein and the other the same image with colour is an elegant way of demonstrating this.

Here the CBD is dilated at 8.7mm, which is greater than the normal range of less than or equal to 6mm(on inner to inner wall measurement) for her age. A CBD of up to 8mm is acceptable after the age of 60. The normal portal vein diameter is 7 -15 mm so a rule of thumb is that if the CBD is the same size or bigger than the portal vein it is  dilated .

The first  clip shows small stones visible in the mid CBD, again identified by their echogenicity and their posterior shadowing.

The second clip shows dilated intrahepatic ducts consistent with CBD obstruction. It is important to also sweep through  the liver to look for dilated hepatic ducts. The hepatic ducts normally lie anterior to the portal veins.

The patient underwent an uneventful cholecystectomy and ERCP the next day.

Impact of point of care ultrasound on patient care:

  •  Immediate bedside confirmation of diagnosis with visualisation of CBD stone
  •  Surgical team able to organise definitive treatment and patient disposition whilst awaiting formal ultrasound.
  • Interestingly the formal biliary ultrasound done later that evening reported as a normal CBD of 5mm and no CBD stones. Operation report the next day confirmed 4 medium sized stones present in the distal CBD.

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