Figure 12a. Emphysematous pyelonephritis in a 45-year-old woman. (a) Abdominal radiograph obtained with the patient upright demonstrates a 2-cm calcification overlying the region of the left ureteropelvic junction (arrow) and several smaller calcifications overlying the lower pole. Note also the mottled collection of gas bubbles in the region of the left lower renal pole (arrowheads) and the large air-fluid level within the upper pole (*). (b) Contrast-enhanced excretory-phase CT scan obtained at the same level as a demonstrates enlargement of the left kidney with persistent parenchymal enhancement relative to the normal right kidney. Note the air-fluid and debris level (*) within the upper pole, a finding that corresponds to the radiographic finding. A large obstructing ureteral stone (arrow) and perinephric inflammatory changes are also present. (c) Photograph of the cut gross specimen reveals diffuse parenchymal necrosis.