Renal and perirenal abscesses.

Our knowledge of the spectrum of renal abscesses has increased as a result of more sensitive radiologic techniques. The classification of intrarenal abscess now includes acute focal bacterial nephritis and acute multifocal bacterial nephritis, as well as the previously recognized renal cortical abscess, renal corticomedullary abscess, and xanthogranulomatous pyelonephritis. In general, the clinical presentation of these entities does not differentiate them; various radiographic studies can distinguish them, however. The intrarenal abscess is usually treated successfully with antibiotic therapy alone. Antistaphylococcal therapy is indicated for the renal cortical abscess, whereas therapy directed against the common gram-negative uropathogens is indicated for most of the other entities. The perinephric abscess is often an elusive diagnosis, has a more serious prognosis, and is more difficult to treat. Drainage of the abscess and sometimes partial or complete nephrectomy are required for resolution.