Pseudostone at ERCP due to juxtapapillary diverticulum

Juxtapapillary diverticula of the duodenum are often encountered at endoscopic retrograde cholangio pancreatography (ERCP) and their presence causes a prominent "pseudostone" appearance on the retrograde cholangiogram in many patients with otherwise normal, i.e. stone-free, ducts. This may lead to inappropriate surgery if not recognised.