The aim of this book is to help the reader achieve the correct diagnosis in the emergency setting, which continues to remain a challenge, given the variety of potential clinical presentations. Diagnostic failure is the largest reason for delays in provision of appropriate treatment, which can be life-saving, and the largest source of clinical complaints and untoward incidents leading to poor clinical outcomes and to litigation. In this book, the readers will find diagnostic checklists, organised according to potential emergency presentations and classified under body systems, including atypical presentations, lists of differential diagnoses and guidance to pattern recognition. Apart from providing an aide-memoire for a range of presentations, it is hoped that the book will allow for better quality and informed referrals, especially between health care providers.  This book is aimed as a rapid reference guide for all levels of medical staff working in emergency and acute care settings in the English-speaking world, but may also benefit nursing professionals and medical students.