This could be a ton of things...Anything from post-surgical adhesions, a hepatic abcess, bowel issues (like diverticuitis), or even a "liver stone" (bile stone that forms where the liver empties into the duct. Also, have you been checked for hepatitis, had any recent strong antibiotics (like Bactrim, etc.), or have issues with a grumpy appendix or a right-sided ovarian cyst? (Referred pain symptoms.)
What do you liver and pancreatic function tests look like? Any elevations? How about your CBCs? The issue may have nothing to do with you bile duct being dilated unless it is "congested" (backed up) from an issue with the common bile duct or pancreatitis. (Usually, you will have BAD epigastric and/or upper left quadrant pain and a fever from this.) I hope this helps and doesn't freak you out more...(((((((HUGZ)))))))~MM
Chris, your doc is probably thinking that you might have had some form of stone within the common bile duct and that the presence of the stone may have resulted in the enlargement of the CBD. However, enlargement of the CBD isn't too uncommon after having the GB removed. He may be 'covering' the bases to make sure all is well, but it could depend on how big the enlargement is. The MRI may be an MRCP which will visualize the ducts of the biliary system.
You may want to check out a condition called SOD: sphincter of Oddi dysfunction.
Thanks for the info, Did you experience pain under your right rib cage? This pain is exactly like the gallstone pain I had i the 80"s prior tosurgey. MD mentioned a tumor, stone that may cause the dilation, I am just trying to figure it all out, and why the sudden onset? Concerned about pancreas involvement due to the ducts joining?