The sonographic appearance of acute pyelonephritis.

Acute pyelonephritis and acute ureteral obstruction often present with similar clinical and urographic findings. Ultrasound, however, can easily detect the presence of obstruction as well as demonstrate characteristic findings suggestive of acute pyelonephritis, and thus allows differentiation. In two patients with acute pyelonephritis, the ultrasonic findings consisted of a large swollen kidney with an increased anechoic corticomedullary area, with multiple scattered low-level echoes. Each of the two cases is discussed in detail.