Perinephric Collection: Hematoma or Duodenal Perforation?

A 74-year-old man presented with a history of collapse and abdominal pain. Initial imaging showed a left sided preirenal collection. The initial working diagnosis was perirenal hematoma secondary to renal trauma. Subsequent patient deterioration led to further imaging which led to the diagnosis of a duodenal perforation with tracking of duodenal contents into the left perirenal space. This important differential should be a consideration in cases of perinephric collections of unknown etiology.