Unusual causes of gastrointestinal bleeding in the intensive care unit through the radiology lens

The great majority of patients admitted to the intensive care unit (ICU) for critical gastrointestinal bleeding (GIB) will have a predictable etiology. Once the site is localized to the upper versus the lower gastrointestinal tract, the number of typically encountered etiological possibilities is quite limited. On rare occasions, the cause of GIB requiring ICU care is not one of the standard considerations, potentially leading to diagnostic and therapeutic delays. Within a short time period, three patients were admitted to our institution's medical ICU each with a different unexpected cause of GIB. All three cases generated a variety of instructive images, which are used in the present series to illustrate these conditions and the role of radiology in their evaluation and management.