When an ultrasound, CT, MRI or MRCP report says the pancreatic duct is “wide”, the main pancreatic duct is “dilated” or there is “dilatation of the duct of Wirsung”, it means the pancreas’s main duct has been seen wider than expected.
This can have simple and harmless causes, but in some situations a condition obstructing the flow in the pancreatic duct may need looking into.
A wide pancreatic duct does not on its own mean pancreatic cancer. But duct dilatation that is newly developed, marked, progressively increasing or accompanied by other abnormal findings should be assessed.
What is the pancreatic duct?
The pancreas produces the enzymes needed for digestion. These secretions reach the main pancreatic duct (the duct of Wirsung) through small ducts within the pancreas, and empty from there into the duodenum.
In most people the main pancreatic duct lies in close relation to the common bile duct before opening into the bowel. This is why changes in the pancreatic duct and the main bile duct are sometimes assessed together.
What should the pancreatic duct diameter normally be?
The main pancreatic duct is quite a fine duct, and its diameter is not the same in every part of the pancreas. In general the duct is:
- Wider in the head of the pancreas
- Narrower in the body
- Narrower still in the tail
Some widening of the pancreatic duct can also be seen with age. So no single “normal pancreatic duct diameter” can be applied to every patient.
Roughly, one of the classic references in adults is a main duct diameter of about 3 mm in the head, 2 mm in the body and 1 mm in the tail; but the imaging method used, the person’s age and where the measurement was taken all have to be taken into account.
It is not right to interpret the millimetre value in a report on its own.
Why does the pancreatic duct widen?
Widening of the pancreatic duct can arise roughly by two mechanisms:
- Something obstructing the flow ahead of the duct
- The duct widening because of age, chronic disease or structural change
The causes can be quite varied.
Can there be a stone in the pancreatic duct?
Yes. In chronic pancreatitis particularly, stones and calcifications can form in the pancreatic duct. These can obstruct the flow of pancreatic secretion and cause the duct to widen.
Where a CT report shows calcifications in the pancreas, a wide duct and atrophy of the pancreatic tissue together, that can matter for chronic pancreatitis.
Does chronic pancreatitis widen the pancreatic duct?
Yes. In chronic pancreatitis the pancreatic duct can show:
- Irregular widening
- Narrowing
- Duct stones
- Changes in the side branches
The duct can sometimes look not like a smooth tube but irregular, widening and narrowing in places.
So it is not only the duct diameter that matters but the shape of the duct too.
Can IPMN widen the pancreatic duct?
Yes. Intraductal papillary mucinous neoplasm (IPMN) is a cystic pancreatic lesion arising from the pancreatic ducts.
In main-duct IPMN in particular, the main pancreatic duct can widen. In side-branch IPMN, cystic widening can be seen in the side branches of the pancreatic duct.
A wide duct does not mean IPMN
Not every patient with a wide pancreatic duct has IPMN. MRI/MRCP and, where needed, EUS findings are weighed together.
Can pancreatic cancer widen the pancreatic duct?
Yes, some pancreatic tumours can cause duct dilatation. If a tumour lying ahead of the pancreatic duct obstructs its flow, the duct can widen behind the blockage.
But a dilated pancreatic duct is not pancreatic cancer. Chronic pancreatitis, duct stones, IPMN, conditions in the region of the papilla and other harmless situations can all lead to a wide duct.
Does where the duct widens matter?
Yes, it matters a great deal.
A sudden cut-off or marked narrowing at a particular point in the pancreatic duct, together with widening of the duct behind it, may need its cause looking into.
Radiology reports sometimes use phrases such as “abrupt cut-off”, “the duct ends abruptly” or “dilatation of the distal pancreatic duct”. Where this is the case, why the duct narrows at that point is investigated.
What does it mean together with “the pancreas is atrophic”?
Atrophy means a reduction in the volume of pancreatic tissue. Some pancreatic atrophy can be seen with age.
But duct dilatation + pancreatic atrophy can also be seen in chronic pancreatitis and in some situations where the duct has been blocked for a long time. Atrophy of the pancreatic tissue behind only one part of the duct in particular may call for more detailed assessment.
What does it mean if both the bile duct and the pancreatic duct are wide?
This is an important imaging finding. Widening of the main bile duct together with the main pancreatic duct is called the double duct sign.
Because the two ducts run very close to each other in a region near the bowel, a problem in that shared region can cause both to widen. In that case the following are assessed carefully:
- The head of the pancreas
- The ampulla of Vater
- The distal bile duct
The double duct sign can be seen in some tumours but is not on its own a diagnosis of cancer. It has harmless causes too.
Why is MRCP requested?
MRCP is a special MRI examination for showing the pancreatic and bile ducts in detail. MRCP can assess:
- The diameter of the main pancreatic duct
- The course of the duct
- Strictures
- Whether the duct is cut off abruptly
- The side branches
- Pancreatic cysts
- The relationship of an IPMN to the duct
- The common bile duct and the bile ducts
Why might EUS be needed?
Endoscopic ultrasound (EUS) allows the pancreas to be imaged in considerable detail. Where the cause of a dilated pancreatic duct cannot be explained on CT or MRI/MRCP, EUS may be done in selected patients.
EUS can be useful particularly in assessing:
- Small pancreatic lesions
- The head of the pancreas
- The ampullary region
- Changes in the duct
- Cystic lesions
Where needed, a tissue sample can also be taken during EUS.
Not every dilated pancreatic duct needs an EUS or a biopsy.
Is ERCP needed?
An ERCP is not usually done simply because a duct has widened. ERCP is an invasive procedure and can have complications, including pancreatitis.
So today, where the aim is only to image the pancreatic duct, methods such as MRCP and/or EUS are usually used first. ERCP is used particularly in selected situations where treatment is needed.
Can amylase and lipase be normal?
Yes.
A wide pancreatic duct does not mean amylase and lipase must be raised. In chronic processes particularly, amylase and lipase can be entirely normal.
So the reasoning “amylase and lipase are normal → there cannot be a problem with the pancreas” is not correct.
Does the pancreatic duct widen with age?
Yes. As age advances, mild widening of the pancreatic duct can be seen.
So an older person with no symptoms and a similar duct diameter on previous imaging is not assessed in the same way as a young person with newly developed duct dilatation.
Why do old images matter so much?
Old CT, MRI and MRCP images are quite valuable where the pancreatic duct is dilated. For example:
- Mild duct dilatation unchanged for 5 years
- Duct dilatation that has increased markedly within 6 months
do not carry the same meaning. This is why it can be useful to compare not only old reports but, where possible, the old images themselves.
Which findings make duct dilatation more important?
More detailed assessment may be needed where pancreatic duct dilatation is accompanied by:
- Newly developed or progressively increasing duct dilatation
- A sudden cut-off in the duct
- A solid lesion in the pancreas
- Regional atrophy of the pancreatic tissue
- A dilated bile duct
- Jaundice
- Unexplained weight loss
- New or unexplained upper abdominal or back pain
- Recurring attacks of pancreatitis
When should assessment not be delayed?
Assessment should not be delayed if pancreatic duct dilatation is accompanied by
Newly developed jaundice · marked and unexplained weight loss · severe or worsening upper abdominal or back pain · persistent vomiting · fever and a poor general condition.
Where jaundice, a dilated bile duct and a dilated pancreatic duct are present together in particular, determining the cause matters.
What should you do if your pancreatic duct is wide?
- Do not panic. Duct dilatation does not on its own mean pancreatic cancer.
- How many millimetres it is and where it was measured are looked at. Measurements in the head, body and tail are not the same.
- It is compared with old images. Newly developed or progressing widening matters more.
- Whether the duct is smooth or irregular is looked at. Strictures, stones or an abrupt cut-off are investigated.
- The pancreas itself is assessed. Whether there are cysts, solid lesions, calcification or atrophy matters.
- The bile duct is assessed too. Widening of both ducts together carries particular importance.
- MRCP or EUS is done where needed. Not every patient needs the same investigation.
Remember
- A WIDE PANCREATIC DUCT Does not on its own mean pancreatic cancer.
- STONES + CALCIFICATION + AN IRREGULAR DUCT Can be seen in chronic pancreatitis.
- DUCT DILATATION + CYSTIC CHANGE May call for assessment for IPMN.
- A WIDE BILE DUCT + A WIDE PANCREATIC DUCT Is called the "double duct sign" and its cause should be looked into.
- MRCP Shows the pancreatic and bile ducts in detail.
- EUS Can assess the pancreas in detail in selected cases where the cause is unexplained.
- AN ABRUPT CUT-OFF IN THE DUCT Is an imaging finding that needs assessing with particular care.
The most important message
A dilated pancreatic duct is an imaging finding; it is not on its own a diagnosis.
The assessment weighs not only the duct diameter but the patient’s age, which part of the duct is wide, whether the widening is new, how smooth the duct is, the pancreatic tissue, the bile duct, the MRI/MRCP findings and the patient’s symptoms.
This is not enough to make a diagnosis
If your ultrasound, CT, MRI or MRCP report says the pancreatic duct or the duct of Wirsung is dilated, diagnosing yourself with chronic pancreatitis, IPMN or pancreatic cancer from that phrase alone is not the right course.
Particularly where the duct dilatation is new or progressing, where the duct is cut off abruptly, or where there is a dilated bile duct, jaundice, weight loss or another abnormal finding in the pancreas, the cause needs looking into properly.
Sources
- Prof. Ali Tüzün İnce, MD