This book is a review of the basic tests available in gastroenterology. Emphasis is placed on these techniques of which the authors have personal experiece. The philosophy has been to evaluate investigations for their current clinical usefulness in the management of patients. A critical analysis has been made to describe those older tests which have proved their worth alongside the newer procedures which have been introduced. Just as some recent additions have rapidly gained importance, some familiar tests have lost significance because of medical progress. Testing for Helicobacter pylori has more use than acid secretory studies in the age when antibiotics have displaced the surgeon in the management of chronic peptic ulcer disease. 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 gastroenterology investigation units. Special thanks are due to the nurses on the Bishop Auckland Gastroenterology Unit, and to Amanda Gallagher who typed the manuscript. Malcolm C. Bateson Ian A.D. Bouchier 1996 Xl CHAPTER 1 H elicobacter pylori INTRODUCTION The discovery of the presence of this organism in many human stomachs and its association with disease has revolutionized our approach to peptic ulcer. Detection of H. pylori infection of the gastric mucosa and proof of its absence after eradication therapy have become pivotal in patient management. EPIDEMIOLOGY H. pylori infection is strongly associated with age and inversely with wealth.