[Ultrasound cystometry with reference to urinary bladder form and bladder filling]

In 103 patients we performed sonographic determination of the volume (V) of the urinary bladder, being the product of the transversal (q), ventrodorsal (t) and craniocaudal (h) diameters, and compared this with the excreted volumes of urine. Depending on the shape and filling of the bladder we found different correlations from which it was possible to calculate three correction factors (F) for the formula V = (q x t x h) x F:F = 1.25 for volumes less than 150 ml; F = 0.9 for spherically sagittal section and volumes greater than 150 ml. The factor 0.5 given in most textbooks on sonography will in the majority of cases result in underestimating the urinary bladder volumes. Accurate sonocystometry taking the shape and filling into consideration is imperative for performing follow-up and treatment monitoring in neurogenic disturbances of voiding of the bladder or occlusive disturbances of flow in the region of the urethra.