bile duct can be an 'incidental' finding long after gallbladder surgery, and most docs say it's something that seems to happen after this form of surgery. It can also suggest, however, that there are stones or sludge present and that could result in enlargement. An enlarged
bile duct can also suggest the presence of disease, so there's not specific 'one thing' that might be causing the problem. Different causes need to be ruled in or out.