Accuracy of ultrasound in the diagnosis of nonfunctioning kidneys

The accuracy and reliability of ultrasound were assessed in 246 patients with 338 radiologically nonfunctioning renal units. The causes of nonfunction included hydronephrosis, pyonephrosis, renal parenchymal disease, renal agenesis, renal neoplasm and polycystic disease. Obstruction was proved in 158 patients, with an accuracy of 98.1 per cent. Retrograde pyelography was avoided. The diagnosis of a small end stage kidney was correct in 42 patients. In 9 patients with a unilateral nonfunctioning kidney less than 9 cm. long a thin coarsely textured cortex with dilatation of 1 or more calices was found. To our knowledge the presence of dilated calices in a small kidney, suggestive of chronic pyelonephritic changes, has not been described previously by ultrasound. Nonvisualization occurred in 16 cases (4.7 per cent) despite the anatomical presence of a kidney. An advanced degree of pyonephrosis with thick inspissated pus sometimes may mimic the ultrasonic appearance of a renal neoplasm.