This book is a completely up-to-date review of the basic tests available in gastroenterology. It is based on a detailed critical analysis of recently described procedures and the review of more traditional methods; each is as- signed its correct place in the modern management of patients. Emphasis is placed on those techniques with which the authors have practical experience. The most useful investigations are indicated in the table of contents by heavy type. Comprehensive references are included to provide information about the selection, performance and interpretation of tests. The book is designed for trainees and clinicians without special expertise in gastroenterology, as well as being a shelf manual for the gastroenterologist and the staff of gastrointestinal investigation units. Special thanks are due to the nursing staff of the Day Ward, Bishop Auck- land General Hospital; Mr P. Grencis, Medical Photographer; Dr S. Desai, Radiologist; and Amanda Gallagher who typed the manuscript. Malcolm C. Bateson Ian A. D. Bouchier 1988 xu CHAPTER 1 Intubation The passage of various forms of nasogastric, duodenal and intestinal tubes is basic to many of the diagnostic procedures performed in the gastrointestinal system. Method Whenever possible the patient's fullest co-operation should be obtained. If the patient is taking any drugs which might influence the test to be under- taken these should be discontinued.