Obstructive uropathy

In the initial assessment and diagnosis of a patient with an obstructive renal lesion, intravenous urography is the primary investigative method, but renography will give important additional evidence about the functional integrity of the obstructed kidney. Intravenous urography can give very misleading information as to function. Once the anatomical facts are established by urography, the degree of obstruction and the changes in function in the obstructed kidney can be followed more efficiently by renography with far less irradiation dosage and less inconvenience to the patient; renography is also less expensive and less time-consuming than intravenous urography.