B-scan ultrasound in the evaluation of renal failure.

Twenty-three patients with blood urea nitrogen (BUN) over 70 and thought clinically to be in renal failure were examined by ultrasound. A correct diagnosis of kidney size and the presence or absence of hydronephrosis or polycystic kidney was made in all but one instance. One kidney in a patient with end-stage renal failure was not seen ultrasonically but was subsequently demonstrated on a retrograde pyelogram. In 10 patients, excretory urography (on 4 occasions with tomography) failed to demonstrate the kidneys adequately. It is suggested that ultrasound should either be the first or second imaging technique in the investigation of patients who present in renal failure of unknown cause.