The first endoscope introduced by Bruening in 1907 was a rigid instrument that allowed inspection of the upper gastrointestinal tract under a general anaesthetic.^w1 Forty years later the first flexible fibreoptic instrument allowed procedures to be done under local anaesthetic or light sedation. It took a further 20 years for the technological evolution of the first colonoscope. A major advance occurred in 1999, when capsule endoscopy enabled complete visualisation of the small bowel.^w2 A capsule is swallowed and propelled through the gastrointestinal tract by the action of peristalsis. It contains an imaging device, which transmits images of the intestine to sensors on the abdominal wall.

Historically the small bowel was considered technically difficult to examine because of its length (3-5 metres), location, and tortuosity.^w3 Previously the small bowel could be partly assessed by a push enteroscope, which is longer (about 2 metres) than a standard gastroscope and therefore allows examination of up to 80-120 cm beyond the ligament of Treitz (anatomically the duodenojejunal flexure), while intraoperative enteroscopy required a general anaesthetic and laparotomy. Barium follow through (small bowel meal) and enteroclysis (double contrast small bowel follow through) allow indirect examination of the small bowel but have a low diagnosis rate.1 ^{w4 w5}

Given the limitations of these other tests, there has been a surge in investigations on the practical diagnostic ability and clinical utility of capsule endoscopy.