Cholangioscopy is a minimally invasive, endoscopic technique that allows direct visualisation of the bile ducts, facilitating both diagnostic and therapeutic interventions. It is a useful tool in managing biliary diseases, allowing characterisation and tissue acquisition for strictures of undetermined aetiology, facilitating extension assessment for biliary cancer and providing intraductal lithotripsy for complex biliary stones.

Examination of the pancreas and biliary and digestive structures by endoscopic ultrasonography (EUS) can be tricky and using it to make a diagnosis can be challenging. Understanding anatomical variations and postoperative modifications is vital when undertaking EUS, as is choosing the correct linear echoendoscope for the structures being examined (e.g. the hilum of the liver versus the tail of the pancreas). There can also be difficulties with tissue acquisition related to tumour location and internal structures, and there are situations when sampling is contraindicated. Consideration also needs to be given to the use of contrast with special settings and difficulties in differential diagnosis (pancreatic solid lesions, indeterminate biliary strictures, gastric neuroendocrine tumours). The role of EUS assessment after neoadjuvant therapy should also be considered. Here we discuss the most frequent mistakes that are made in pancreatobiliary and digestive EUS imaging. 

 Upper GI-endoscopy is one of gastroenterology's most frequently performed diagnostic and interventional methods. Even though gastroscopy is believed to be a routine investigation - which is the greatest mistake of all - several pitfalls in performance can cause serious problems or misdiagnoses. Struggles in accurately describing and classifying abnormal findings can occur and concern the correct basic technique of endoscope introduction, and the correct way of investigating the mucosal surface in total, with several available imaging modalities such as virtual chromoendoscopy or magnification. Which classification systems should be used? The decision to perform additional workup needs to be made immediately during the ongoing endoscopy. Is it necessary to take biopsies, or should it even be avoided due to potential interference with a later endoscopic resection? This article answers the questions, highlights the most common mistakes with clinical relevance and expands on how to avoid them.