Emphysematous pyelitis and emphysematous pyelonephritis characterized by computerized tomography.

We report three cases of emphysematous pyelonephritis, all of them associated with perinephric emphysema, and one case of emphysematous pyelitis to demonstrate the value of computerized tomography (CT) in both diagnosis and patient management. The differentiation between air in the collecting system (emphysematous pyelitis), air within the parenchyma (emphysematous pyelonephritis), and air in the perinephric space (perinephric emphysema) may have significant prognostic (survival) and therapeutic (medical vs surgical) implications. Computerized tomography is currently the best method for demonstrating intrarenal air and for characterizing the location of that air (intracalyceal, intraparenchymal, perinephric, or pararenal).