'It's all foreign to me': how to decipher gastrointestinal intraluminal foreign bodies

In evaluating the gastrointestinal tract, whether in the emergency room setting, the inpatient setting or the outpatient setting, the radiologist may encounter a myriad of intraluminal radio-opaque, non-anatomic entities. It is the radiologist's role to distinguish between true foreign bodies and medical paraphernalia. Further, the later must be evaluated for proper positioning vs. improper, potentially detrimental positioning. While many foreign bodies from the community may be distinctly familiar to the radiologist, the large variety of medical tools in existence may not be. Furthermore, many medical devices are designed to transiently traverse, or interact with the gastrointestinal tract, requiring the radiologist to become familiar with their natural history. We explore a select group of common and uncommon intraluminal foreign bodies and will divide them into medical paraphernalia that are properly positioned; medical paraphernalia that are in abnormal locations and miscellaneous foreign bodies from the community. For each medical tool, we will discuss its development and medical utility, natural history as it relates to the gastrointestinal tract, optimal positioning as assessed radiologically, malpositioning, and subsequent complications. A small selection of unusual foreign bodies from the community will be presented. Finally, a selection of medical conditions which produce symptoms due to acquired intraluminal objects will be reviewed.