Overview of the imaging progression with comments:
- Choledocholithiasis at presentation. This can be definitely diagnosed on the CT and does not require MRCP before ERCP.
- Post-ERCP interstitial edematous pancreatitis with persistent choledocholithiasis, likely due to the multiplicity of small stones filling much of the CBD. No further intervention was performed, and the small remaining stones likely spontaneously passed based on the follow-up scan.
- Multiple organizing collections in the abdomen and retroperitoneum at 3 weeks. Although the pancreas is enhancing symmetrically, the appearance of peripancreatic collections containing variable amounts of fat suggest a necrotizing component, complicating management. The collections do not look well-defined enough to be categorized as pseudocysts or walled-off necrosis at this time, which generally happens after 4 weeks, when a fibrous capsule/granulation tissue surround more discrete collections.