Widened bile duct seen by chance on a scan
An ultrasound, CT or MRI done for another reason may report a dilated (widened) common bile duct. Bile ducts are the tubes that carry bile, a digestive juice made by the liver, to the small intestine. (MedlinePlus) A US radiology expert panel says this is a common chance finding and is unlikely to mean a blockage without symptoms or raised liver blood tests. (AJR 2024) This page covers what it means and what checks usually follow, not treatment.
The main guidance
- AJR Expert Panel (US radiology, 2024): a widened bile duct is common and unlikely to mean a blockage when there are no symptoms and liver function tests are normal. The panel sets criteria for a widened duct that allow for gallbladder removal and older age. (AJR 2024)
- ACR white paper (American College of Radiology, 2013): includes advice on bile duct widening seen by chance on CT and MRI, alongside gallbladder findings. (ACR 2013)
- NICE NG12 (UK): does not cover a widened duct on a scan, but says people aged 40 or over with jaundice (yellow skin or eyes) should be referred on the suspected cancer pathway for the pancreas. (NICE NG12)
How normal width changes with age
The common bile duct gets wider with age in people with no bile duct disease, so a width that is above a fixed limit may still be normal for an older adult. (SHIP 2023)(Peng 2015)(Herrera-LeBlanc 2022)
| Study and scan | What it found |
|---|---|
| 938 healthy adults, MRI (SHIP, Germany) | Upper normal width up to 8 mm under 65 and up to 11 mm at 65 or over; 10.9% were above the usual 7 mm limit (SHIP 2023) |
| 862 adults without symptoms, MRI (China) | Average 4.1 mm, widening about 0.03 mm a year; suggested upper limit 6 mm (Peng 2015) |
| 608 adults, ultrasound (Mexico) | Average 3.8 mm under 30, 4.9 mm at 50 to 59, 5.4 mm at 60 to 69 and 6.9 mm over 70 (Herrera-LeBlanc 2022) |
After gallbladder removal
In the German population study, the upper normal width in people who had their gallbladder removed was about 13.5 mm, compared with about 9 mm in those who had not. (SHIP 2023) A study that scanned 48 people before and after gallbladder removal found parts of the duct were wider 3 and 6 months later. (Pavlovic 2020) The expert panel's criteria allow for this. (AJR 2024)
What a cause turns out to be
- How often a cause is found: a review of 9 studies of widened ducts found by chance found a cause in 33% on average. The most common were a stone in the bile duct, long-term inflammation of the pancreas (chronic pancreatitis) and a small pouch in the bowel wall near where the duct drains (periampullary diverticulum). (Smith 2015)
- What pointed to a cause: in that review, the width itself was not linked to finding a cause. Older age, jaundice and widening of the smaller ducts inside the liver as well were. Widening of both the bile duct and the pancreatic duct suggested a problem in the pancreas. (Smith 2015)
- Over time: in the studies that followed people for 6 to 85 months, the diagnosis generally did not change. (Smith 2015)
What usually comes next
- Liver blood tests: the expert panel bases its approach on symptoms and liver function tests. (AJR 2024) For what each result means, see liver function test results.
- Why the tests matter: in a hospital study of 68 people without symptoms who had an MRI scan of the bile ducts, a significant cause was found in 61.9% of those with abnormal liver tests and 27.7% of those with normal tests. The authors say almost a third with normal tests still needed more checks. (Tamir 2017)
- Repeat or extra imaging: the expert panel gives guidance on when more imaging or tests are worth it. (AJR 2024) Your doctor decides whether you need any.
What the finding does and does not show
- A measurement on one scan is not a diagnosis. Limits differ between ultrasound, CT and MRI studies, and between groups of people. (SHIP 2023)(Peng 2015)(Herrera-LeBlanc 2022)
- For related findings, see gallstones found by chance, gallbladder polyp found by chance and pancreatic cyst found by chance.
NHS, when to get help: (NHS jaundice)(NHS gallstones)
Ask for an urgent GP appointment or get help from NHS 111 if:
- your skin or the white part of your eyes look yellow
- you have pain in your tummy that lasts longer than 30 minutes
You may also have itchy skin, darker pee and paler poo than usual.
Call 999 or go to A&E if:
- you have sudden, severe pain in your tummy
- you have pain that spreads from your tummy to your back, and are being sick
- your temperature is very high, or you feel hot, cold or shivery
- your skin or the white part of your eyes looks yellow
In the US, the emergency number is 911.
Routine age-based screening
A finding on a scan does not replace the routine screenings for your age. See screenings by age and gender and after an abnormal screening result.
Where they differ:
- What counts as widened. The usual limit is 7 mm. (SHIP 2023) A Chinese MRI study suggests 6 mm. (Peng 2015) The German population study suggests age-based limits of 8 mm under 65 and 11 mm at 65 or over. (SHIP 2023)
- Normal liver tests. The expert panel says a blockage is unlikely without symptoms or raised liver tests. (AJR 2024) One hospital study still found a significant cause in 27.7% of people with normal tests. (Tamir 2017) The review of 9 studies says a widened duct found by chance can be a sign of serious disease and that the best approach is not yet settled. (Smith 2015)
- After gallbladder removal. The German population study found a wider normal range. (SHIP 2023) The authors note that other studies dispute this. (SHIP 2023)
Your doctor decides what your result means for you.
Questions people ask
Is a widened bile duct serious?
Often not. A US radiology expert panel says a widened bile duct is a common chance finding and is unlikely to mean a blockage when there are no symptoms and liver blood tests are normal. A review of 9 studies found a cause in about a third of people, most often a stone in the duct. (AJR 2024) (Smith 2015)
Does the bile duct get wider with age?
Yes. In a large German population study of healthy adults, the upper normal width was up to 8 mm under age 65 and up to 11 mm at 65 or over. A Chinese study found the duct widened by about 0.03 mm a year. (SHIP 2023) (Peng 2015)
I had my gallbladder removed. Is a wider duct normal?
It can be. In the German population study, the upper normal width after gallbladder removal was about 13.5 mm, wider than in people who still had a gallbladder. A small study found parts of the duct were wider 3 and 6 months after the operation. (SHIP 2023) (Pavlovic 2020)
Why do my liver blood tests matter?
In an Israeli hospital study of people without symptoms, an MRI scan of the bile ducts found a significant cause in 61.9% of those with abnormal liver tests, compared with 27.7% of those with normal tests. The expert panel also bases its approach on symptoms and liver tests. (Tamir 2017) (AJR 2024)
When should I get help straight away?
The NHS says to call 999 or go to A&E for yellow skin or eyes with sudden severe tummy pain, pain spreading to the back with being sick, or a very high temperature. It advises an urgent GP appointment or NHS 111 for yellow skin or eyes on their own. (NHS gallstones) (NHS jaundice)