Clinical use of patency capsule: A comprehensive review of the literature

The patency capsule is a radiopaque, dissolvable diagnostic tool, similar in shape and size to small bowel capsule endoscopes. It was developed to offer a simple, safe, efficient, and accurate evaluation of small bowel functional patency. Although unable to provide direct visual information regarding the presence and location of strictures, masses, or luminal narrowing of the small bowel, a successful patency test minimizes the risk of retention and allows the safe administration of a capsule endoscope. However, its use entails a low risk of potentially harmful adverse events, which in their majority are indolent and resolve spontaneously. Abdominal pain and symptomatic retention are accountable for the majority of reported adverse events, whereas a limited number of reports describe life-threatening complications, namely intestinal obstruction, perforation, and intestinal ischemia. Computed tomography is the modality of choice for the identification of the exact position of an impacted patency capsule, whilst the use of plain abdominal radiographs should be avoided for the evaluation of the patency capsule position, as they provide false information. Hereby, we present a comprehensive review of the available literature regarding the characteristics, indications, clinical use, effectiveness, and adverse events of the patency capsule.