Clinical Question: Is computed tomography (CT) or intravenous pyelography (IVP) the preferred imaging study for evaluating patients with microhematuria?
Setting: Outpatient (specialty)
Study Design: Cohort (prospective)
Synopsis: Noncontrast CT is more accurate than IVP in the evaluation of symptomatic patients with flank pain with or without microhematuria. Less is known about the best imaging test for the evaluation of patients with asymptomatic microhematuria. In this study, 115 patients presenting to a urology clinic with asymptomatic microhematuria underwent CT and IVP before cystoscopy. The two tests were separated by at least five days to avoid contrast-induced renal insufficiency. Scans were evaluated by radiologists blinded to the results of the other imaging study. Pathologic evaluation served as the gold standard when clinically feasible. When no histology was available, the study with the higher reported accuracy in the literature for a particular disease entity was defined as accurate.
Overall, abnormalities were identified in 38 patients (33 percent). In 77 patients, no cause for hematuria was found in either study. False-positive results were reported by CT in two cases and by IVP in seven cases. The sensitivity of the CT was 100 percent and the specificity was 97.4 percent. The sensitivity and specificity of IVP were less accurate, with measures of 60.5 percent and 90.9 percent, respectively. Forty nonurologic diagnoses were made by CT, including abdominal aortic and iliac artery aneurysms. No additional diagnoses were made by IVP. Although the initial costs of CT were higher, additional radiography was recommended after only four CTs, compared with 20 IVPs. Thus, the overall costs were similar.
Bottom Line: CT is more accurate than IVP in assessing the cause of asymptomatic microhematuria. The use of CT also requires less additional imaging. (Level of Evidence: 2b)