Acute focal bacterial nephritis or renal abscess? A sonographic diagnosis

The radiological and sonographic findings of acute focal bacterial nephritis in 3 patients are presented. The sonographic appearance of a poorly marginated mass in the renal cortex, with echo amplitude less than the normal parenchyma and with poor transmission, should suggest the diagnosis of acute focal bacterial nephritis in a patient with pyrexia and a tender renal mass. These features of poor echogenicity and lack of posterior enhancement contrast with the presence of patchy echogenicity and posterior enhancement found in the renal abscess. This is of surgical importance, as the management may tend to be conservative in the one and surgical in the other.