The diagnostic yield of intravenous urography: a demographic study

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Abstract
To examine the impact of intravenous urography (IVU) on patient management in unselected patients in an effort to identify groups in which the use of urography could be reduced. The results of IVU in 235 consecutive unselected patients were assessed prospectively to establish the value of IVU in patient management. Patients were divided into subgroups on the basis of age, sex, presenting symptoms and source of referral. The percentage of examinations with findings affecting patient management was taken as the 'positive diagnostic yield.' Differences between the positive diagnostic yields of IVU in the various groups were examined using the chi 2 test. For all patients the diagnostic yield was 37.4%. In patients over 50 years of age the yield was 46% while below that age the yield fell to 20%. This difference was significant (chi 2 = 13.88, P < 0.001). There were no significant differences between the other defined groups. Specifically, patients referred by general practitioners were as likely to have an IVU abnormality as were patients referred by a hospital practitioner. Patients with painless microscopic haematuria had a lower diagnostic yield (20%) than the other groups examined but this was not significant. IVU has a high diagnostic yield in an unselected population. Although the yield is lower in younger patients IVU offers advantages over other techniques in the investigation of urolithiasis--the commonest positive diagnosis in this study. We argue that it should retain its position as the primary investigation for the majority of patients with urological disease, particularly those suffering loin pain or haematuria.