Objectives: We have developed a totally noninvasive urodynamic technique based on the concept of Doppler sonography, which was tested in men with and without bladder outlet obstruction. Materials and Methods: An ultrasonic image directed Doppler system with a 3.75 MHz. micro-convex electro-probe was operated transperineally using a specially devised remote control robotic holder. Uroflow rates from the urethral meatus were also measured with a flowmeter. The color Doppler ultrasound image and digital flow velocity data were processed by a personal computer. Color scale data were analyzed by customized software. Multiple rectangle sample volumes could be set in any size in any position, and the resulting color encoded data were averaged. Calculation was performed every 0.5 second and a flow velocity curve in the region of interest was obtained. A total of 12 men, 6 without (controls) and 6 with bladder outlet obstruction, were evaluated by conventional pressure flow study and the new Doppler ultrasound urodynamic system. Bladder outlet obstruction was determined using the nomogram of Abrams and Griffiths. The sample volume for a flow velocity curve was set only in the prostatic urethra and, thus, maximum flow velocity in and functional cross-sectional area of the prostatic urethra were determined. Results: Urinary stream in the male urethra was clearly detected and flow velocity in the prostatic urethra could be measured in all cases. Maximum flow rate measured by a flowmeter was significantly lower in the bladder outlet obstruction group. Maximum flow velocity by Doppler study was almost the same in the obstructed and control groups. Functional cross-sectional area, which was calculated by dividing maximum flow rate by maximum flow velocity, was lower in the bladder outlet obstruction (mean plus or minus standard deviation 0.31 ± 0.16 cm.2) than control group (0.78 ± 0.23 cm.2) (p = 0.006). Velocity flow plots were possible in both groups. Conclusions: The concept of noninvasive pressure flow-like urodynamic evaluation based on Doppler ultrasound is feasible. Parameters of flow velocity as well as functional cross-sectional area can be used in the diagnosis of bladder outlet obstruction and to localize the site of obstruction.
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