[Emphysematous cystitis with inversion of the contrast and urine levels inside a bladder diverticulum in computerized tomography].

We report a case of emphysematous cystitis in a 70-year-old male with acute urinary retention. Patient evaluation included a CT scan that disclosed a large diverticulum in the bladder and inverted contrast medium-urine level. We discuss the possible causes of this unique, paradoxic and infrequent finding, which often indicates the presence of infectious sediment in the bladder.