Episode 11: A Dilated Bile Duct
Author: Dr. Terance Lee
Editor: Dr. Suneet Sood
Narrators: Thong Yi Kun, Alan Koay
Today we have a patient case with what appeared to be a simple provisional diagnosis but things took an unexpected turn when the team came across surprising investigational results.
Ah! Shall we start right away then?
A 60-year-old male presented to the clinic with upper abdominal pain. The history and examination findings were consistent with gastritis – epigastric pain with history of similar episodes, associated with meals and no overt abdominal tenderness upon palpation.
That seems straightforward. A clinician would have to rule out gallstones, I suppose?
Before I proceed, I would like to relay one more information about the patient. Upon general inspection, the doctor noticed bowing of the patient’s left leg a little above his ankle, but this was not explored further.
Like you, the resident also considered gallstones, and ordered ultrasonography of the patient’s abdomen. To his surprise, he found the common bile duct to be 9mm in diameter.
9mm? That is a dilated duct I supposed. Are we looking at a case of biliary obstruction? What were the other findings?
Yes, you’re right: the bile duct was dilated. The average diameter is about 4.8 mm, and most radiologists consider a diameter greater than 6 mm to be abnormal.
Number one priority is to rule out obstructive causes such as choledocholithiasis – gallstones causing obstruction in the common bile duct. No stones were visualized in the ducts and the gallbladder from the ultrasound. And if we look back at the patient’s presentation, there were no signs of cholestasis such as jaundice, pale stool or dark urine. He did not present with fever or loss of weight. Murphy’s sign was negative and there was no palpable gallbladder.
The jigsaw pieces do not seem to fit here. So, what happened next?
The patient was admitted into the ward and blood investigations were done. With a dilated bile duct, the treating team expected to find an elevated alkaline phosphatase. And sure enough, the report on liver enzymes showed a rise in alkaline phosphatase – but other enzymes levels were within normal limits.
Let’s have a quick recap here. We have gone through quite a bit. The positive findings that we have for this patient are these 3 – abdominal pain, dilated common bile duct and now, an elevated alkaline phosphatase level. ALP further supports an obstructive cause in the bile duct.
Yes, you’re correct with that observation. But keep in mind that in a case of hepatobiliary origin, we usually expect abnormalities in other liver enzymes such as GGT level (gamma-glutamyl transferase ) and particularly, an elevated bilirubin, which was not the case in this patient.
Ah, that is mind-boggling. How did the team proceed?
The team decided to have a definitive answer by scheduling an ERCP – endoscopic retrograde cholangiopancreatography.
The good news is the result was clear. The patient did not have any obstruction in the bile ducts. He was treated as gastritis and his symptoms was resolved.
That is in fact good news for the patient. But we do have some questions unanswered.
Yes – 2 important questions. What is causing the rise in alkaline phosphatase, and how do we explain the dilated common bile duct?
Let’s answer the first question. Do you remember that I appear to deviate at one point to highlight an observation about his leg?
Yes! There was the skeletal deformity that you had mentioned earlier.
In this case, the treating team had, far too quickly, attributed the raised alkaline phosphatase level to the hepatobiliary system. In fact, this enzyme is also concentrated in bones, kidneys, intestinal mucosa and placenta. The fact that this is an isolated increase in ALP should cause us to consider other differentials. High bone turnover can cause an elevated ALP. Examples would be bone tumors, Paget’s disease of the bone and even healing fractures. Other conditions include hyperparathyroidism, lymphoma and sarcoidosis.
And our patient here was diagnosed with Paget’s disease before, and was under orthopaedic care.
Wow, that is interesting and unexpected. How about the dilated bile duct then?
A senior doctor reviewed the case again and believed that the dilated common bile duct was due to the physiological process of aging. We often do not realize that the bile duct may be quite wide in the elderly. For this patient, the bile duct diameter was within normal limits.
Thank you Dr for the very interesting and informative case. We shall recap a few of the learning points we have covered today.
- Even old age can result in bile duct dilatation.
- An elevated alkaline phosphatase level does not necessarily mean hepatobiliary disease. Disorders in bone and elsewhere may also raise the ALP levels.
When the facts that are presented do not seem to paint the overall picture, one must take a step back and scan all the findings again, including the ones that do not seem to be relevant. In this case, it would be the bowing of the leg, which will quickly explain the elevated ALP if the diagnosis of Paget’s was known earlier. And it turns out that common things are common. The abdominal pain was gastritis after all!
Thank you for listening to our podcast and keep updated with our future entries!
- Holm AN, Gerke H. What should be done with a dilated bile duct? Curr Gastroenterol Rep. 2010 Apr;12(2):150-6.
- Friedman LS. Approach to the patient with abnormal liver biochemical and function tests [database on the Internet]. In: Chopra S, Grover S, ed. Waltham, MA: UpToDate Inc; 2017 Jan 30 [cited 2017 May 28]. Available from: http://www.uptodate.com