Urinary Tract Obstruction and Infection

Abstract

In most patients, ureteral obstruction results from an acute process with associated symptoms. Some controversy exists as to which imaging studies are best for investigating suspected ureteral obstruction. In most hospitals in the United States, non-contrast helical computed tomography (CT) is preferred because it is safe and extremely rapid, and the accuracy rate for detecting ureteral stones, the most common cause of ureteral obstruction, exceeds that of other imaging studies. Other causes of acute abdominal pain, such as appendicitis, leaking aortic aneurysm, and diverticulitis, can also be readily diagnosed and occur in 13–19% of cases. Non-contrast helical CT has an overall accuracy of 97% for diagnosing ureteral stone disease [1]–[8]. This far exceeds the accuracy of intravenous urography (IVU) or ultrasonography (US) (See Table 1). Regardless of composition, virtually all ureteral stones have high attenuation values, making them readily detectable with CT. Nonmineralized matrix stones and some drug-related stones (due, for example, to protease inhibitors) may not be visible on CT images, but are rarely encountered.