Assessment of pyeloureteral function using a flow velocity and cross-sectional diameter probe

The response of the healthy pyeloureteral system of the pig to stepwise increments of urine flow was measured using a flow-velocity, diameter probe. The following urodynamic parameters were measured: renal pelvic pressure, ureteral flow-velocity and diameter, and associated bolus volume in the range of urine flow rates of 0.3 to 10 ml per min. The results show that the diameter sensoring portion of this probe can reliably sense ureteral peristalsis over the entire range of urine flow rates; small alterations in ureteral diameter occurring in dilated ureters after high diuretic loads can also be detected. Data obtained using the flow-velocity portion of this probe indicate that at urine flow rates less than 0.5 ml per min flow-velocity changes of a bolus can be reliably identified. At these flow rates the maximum flow-velocity occurs at the leading edge of the bolus and is invariant with the size of the bolus. At urine flow rates more than 1 ml per min the flow-velocity curve is polyphasic, indicative of an alteration in the mechanism of urine transport by the ureter at these flows. Collectively, data obtained using this probe provide dynamic information concerning the physiologic properties of the upper urinary tract not currently attainable in existing pressure/flow methodologies.