[Urological and nephrological emergency--value of diagnostic imaging]

Many diseases of the kidneys and the urinary tract may develop to urinary emergencies. A prompt evaluation of these critical situations is of utmost importance concerning therapeutic consequences, and implicates a considerable challenge for the radiologist. The use of the appropriate imaging method allows rapid diagnosis, and thus enables optimal therapeutic management. In this article we describe the most important urinary emergencies: urolithiasis, hydronephrosis, acute renal infection, acute obstruction, testicular torsion, complications after renal transplantation, and urinary trauma. Aetiology and pathogenesis of the specific entities are described as well as the use of the adequate imaging method. In addition, especially for CT examinations precise imaging techniques are reported. Complications and differential diagnosis of the specific emergencies are mentioned.