New frontiers in capsule endoscopy.

Capsule endoscopy (CE) was launched at the beginning of this millennium and has since become a well-established tool for evaluating the entire small bowel for manifold pathologies. CE far exceeded our early expectations by providing us with a tool to establish the correct diagnosis for elusive gastrointestinal (GI) conditions such as obscure GI bleeding, Crohn's disease, polyposis syndrome, and others. Recent evidence has shown CE to be superior to other imaging modalities, such as small bowel follow-through X-ray, colonoscopy with ileoscopy, computerized tomographic enterography, magnetic resonance enteroclysis, and push enteroscopy, for diagnosing small bowel pathologies. Gastroenterologists would prefer the convenience of a single capsule that can create images of the area from the oral cavity to the anal canal in one 'shot'. Because of anatomic and physiologic differences in the GI tract, however, it may not be possible to use the same capsule and so we would need a different one for each organ. In addition to the pioneer small bowel capsule, there is now an esophageal capsule, and a colonoscopy capsule will soon be available. The ideal CE should be capable of performing a biopsy or carrying out an online analysis (an 'optical' biopsy) and 'stop' bleeding by an epinephrine injection, a heat probe, argon plasma coagulation, etc. The ultimate capsule would include special detectors for white blood cells, and it would check oncological markers (e.g. CEA, CA 19-9), perform serology tests (e.g. antiendomysial, IgE), and measure various cytokines, pH levels, temperature and pressure, as well as deliver drugs. The capsule's motility feature in the small bowel may open a window to study the pathophysiology of relatively elusive medical entities, such as irritable bowel syndrome. The optimal capsule needs to contain an automatic computerized system for automatic detection of pathologies, such as that present in the ECG-Holter recording, in order to overcome the drawback of time-consuming viewing. Our dream is that endoscopists will be able to 'control and steer' the CE, as they are able to do in standard endoscopy. This would mean being able to maintain the capsule steady in a selected area and hold the view in order to have more time to examine the opposite wall of the bowel. In conclusion, future gastroenterologists will have a number of CEs from which to choose, according to the purpose of the evaluation, whether it be diagnostic and/or therapeutic. Just as the idea of a swallowed capsule taking images as it travels along the human anatomy was once in the realm of sheer fantasy, we have every reason to believe that the ultimate CE will become a reality in the not far distant future.