A comparative study of methods of estimating renal size in normal adults.

One hundred live related voluntary kidney donors were studied prospectively. During donor nephrectomy the actual kidney bipolar length was measured and compared to the renal bipolar length estimated from abdominal sonogram, abdominal plain X-ray, intravenous pyelogram, and renal angiogram. Ultrasound was found to measure the kidney more accurately (mean difference between estimated size and actual = -3.4 mm +/- SD 6.96), than plain X-ray (mean difference from actual 13mm +/- SD 5.24), IVP (mean difference from actual 16.9 mm +/- SD 5.74), and renal angiogram (mean difference from actual 15.2 mm +/- SD 5.77).