Principles of gastrointestinal endoscopy

Endoscopes, both rigid and flexible, are used in many surgical specialties. They allow for minimally invasive investigations of symptoms, diagnosis of pathology and application of directed therapies. Although the ability to see inside the human body has challenged pioneers of medical science for centuries, it is only in the last 100 years that technology has evolved to produce the advances in computers, fibreoptics and mechanics required for endoscopy.This article provides an overview of rigid and flexible endoluminal endoscopy, focussing on the common examinations of the GI tract, namely oesophagogastroduodenoscopy (OGD), sigmoidoscopy and colonoscopy. Laparoscopy, the most common form of rigid endoscopy, is discussed elsewhere in this series.