Measurement of residual urine volume by means of ultrasonic scanning: a comparative study.

The basis for this paper was 107 ultrasonic examinations of the bladder in 20 patients with neurogenic bladder dysfunction. The residual urine volume was estimated in three different ways. 1. The residual urine volume is approximately equal to the product of the width, height and depth of the bladder multiplied by a correction factor. 2. By a new method: The residual volume is approximately equal to the cross-sectional area of the bladder when measured in the sagittal plane multiplied by the width of the bladder. 3. By the nomogram method: The cross-sectional area in the sagittal and the transverse plane are respectively plotted into a specially designed nomogram giving an estimate of the residual urine volume. The bladder was emptied by catheterisation immediately after the ultrasonic examinations. Of the three methods, number 2 was found to give the most accurate estimate of residual urine volume.