Esophagogastroduodenoscopy (EGD), employs a camera attached to a long flexible tube to view the upper portion of the gastrointestinal tract, namely the esophagus, the stomach, and the beginning of the first part of the small intestine called the duodenum. A colonoscope, inserted through the rectum, can view the colon and the distal portion of the small intestine, the terminal ileum. These two types of<unk>  however cannot visualize the majority of the middle portion of the small intestine.<unk>  is therefore used to examine parts of the gastrointestinal tract that cannot be seen by standard<unk> . It is useful when the 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<unk>  include diagnosis of unexplained bleeding, iron deficiency, or abdominal pain, searching for polyps, ulcers, and tumors of the 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 emitted by some<unk> s can be used to accurately estimate the location of the<unk>  and to track it in real-time inside the body and gastrointestinal tract.<unk>  can still not yet replace standard<unk>  for various diseases, as is the case 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<unk> .
Capsule endoscopy
Sialoendoscopy
Nasoendoscopy
Chromoendoscopy
Stool test
Hydrogen breath test
Double-balloon enteroscopy
Urea breath test