The value of ultrasound in previously undiagnosed renal failure.

Rapid advances in equipment and diagnostic criteria have made ultrasound sufficiently sensitive to replace high-dose urography (with its attendant risks and often lengthy examination time) as the initial imaging modality in renal failure. A prospective study was carried out in 56 patients (109 kidneys). All hydronephroses were accurately detected on ultrasound. 80% were due to obstruction, but showed no features that distinguished them from other causes of hydronephrosis. A diagnostic pathway is suggested.