Ultrasonic measurement of renal inclination; its importance in measurement of renal length

In many X-ray departments the renal bipolar lengths are routinely measured on intravenous urogram films. Whether or not a magnification factor is taken into account to allow for the distance of the kidneys from the film, it is generally assumed that the kidneys lie parallel to the film. Routine ultrasound examinations of the liver frequently show the right kidney (Taylor and Hill 1975), and we have noted that the angle of inclination of the right kidney is not constant from patient to patient. We have therefore performed a retrospective study of 100 patients whose livers had been examined by ultrasound. The renal angle was measured, correlated with age and sex and assessed to determine its influence on X-ray measurements of renal length.