[Diagnosis of "severe" renal insufficiency of unknown origin: value and respective roles of ultrasonography and intravenous urography (author's transl)].

A retrospective study in 46 patients hospitalised with severe renal insufficiency of unknown origin, and investigated by means of a straight x-ray of the urinary system followed by bilateral renal ultrasonography, emphasises the importance of the latter examination for establishing the medical or surgical origin of the affection. Intravenous urography, which carries certain risks and does not supply supplementary information, can sometimes be avoided, but it is essential when dilated cavities are seen on ultrasonography. In the absence of the latter sign it should be performed when there is clinical evidence of an obstruction, or when the kidneys are of normal size of enlarged, depending on the results of biological tests or the clinical history. The only contraindication to its use is when ultrasonography has shown two small kidneys with thin cavities resulting from an acute episode of a pre-existing chronic nephropathy.