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.

Alteration of common coagulation tests and thrombocytopenia represent an integral part of the clinical picture of patients with advanced chronic liver disease. As such, the International Normalised Ratio (INR) for prothrombin time is part of the Model for End-stage Liver Disease (MELD) score, which is commonly used to assess prognosis and the need for liver transplantation in patients with cirrhosis. Thrombocytopenia—being mainly related to hypersplenism and decreased synthesis of thrombopoietin by the liver—can also be used to identify the presence of portal hypertension and decreased liver function in patients with chronic liver disease.