Capsule endoscopy is a procedure used to record internal images of the gastrointestinal tract for use in medical diagnosis. The capsule is similar in shape to a standard pharmaceutical capsule, although a little larger, and contains a tiny camera and an array of LEDs powered by a battery. After a patient swallows the capsule, it passes along the gastrointestinal tract taking a number of images per second which are transmitted wirelessly to an array of receivers connected to a portable recording device carried by the patient. The primary use of capsule endoscopy is to examine areas of the small intestine that cannot be seen by other types of endoscopy such as colonoscopy or esophagogastroduodenoscopy (EGD).
Esophagogastroduodenoscopy (EGD), employs a camera attached to a long flexible tube to view the upper portion of the gastrintestinal tract, namely the esophagus, the stomach and the beginning of the first part of the small intestine called the duodenum, and a colonoscope, inserted through the rectum, can view the colon and the distal portion of the small intestine, the terminal ileum, however, these two types of endoscopy cannot visualize the majority of the middle portion of the small intestine. Capsule endoscopy is used to examine parts of the gastrointestinal tract that cannot be seen with other types of endoscopy. It is useful when disease is suspected in the small intestine, and can sometimes be used to find the site of gastrointestinal bleeding or the cause of unexplained abdominal pain, such as Crohn's disease. However, unlike EGD or colonoscopy it cannot be used to treat pathology that may be discovered. Common reasons for using capsule endoscopy include diagnosis of unexplained bleeding, iron deficiency, or abdominal pain, searching for polyps, ulcers and tumors of small intestine, and diagnosis of inflammatory bowel disease. The images collected by the miniature camera during a session are transferred wirelessly to an external receiver worn by the patient, using any one of a band of appropriate frequencies. The collected images are then transferred to a computer for display, review and diagnosis. A transmitted radio-frequency signal can be used to accurately estimate the location of the capsule and to track it in real time inside the body and gastrointestinal tract. It is unclear if capsule endoscopy can replace gastroscopy for those with cirrhosis.
As of 2014 research was targeting additional sensing mechanisms and localization and motion control systems to enable new applications for the technology, for example, drug delivery. Wireless energy transmission was also being investigated as a way of providing a continuous energy source for the capsule.
Capsule endoscopy is considered to be a very safe method to determine an unknown cause of a gastrointestinal bleed. The capsule is usually excreted with the feces within 24–48 hours. There has been a report of retention of the capsule for almost four and a half years although the patient was asymptomatic. However, the risk of bowel obstruction may be countered by abdominal X-ray to locate the device for removal by endoscopy or surgery