[A comparative study of different urodynamic methods used in the diagnosis of lower urinary tract obstruction in men]

The present study compared the results of the different urodynamic methods utilized in the diagnosis of urinary obstruction.

A urodynamic study was performed in 105 patients with prostatism; mean age 66.19 years. The following five urodynamic methods were utilized: maximum pressure/maximum flow rate (Pmax/Fmax), pressure/flow nomogram, pressure/flow curve, Schaefer's PURR and the resistance square.

The Pmax/Fmax method showed the lowest percentage of obstruction (61%), 48% of the nomograms were inconclusive, the pressure/flow curve diagnosed obstruction in 88%, Schaefer's PURR diagnosed obstruction in 77% and the resistance square diagnosed obstruction in 78% of the cases. When the nomogram findings were diagnostic, no significant differences between the other methods were observed. The Pmax/Fmax, pressure/flow curve and the PURR methods proved to be independent methods, while the resistance square showed no significant differences with Schaefer's PURR. An irregular bladder at cystography was associated with a significantly higher percentage of obstruction (72% vs 92%). Lengthening and compression of the prostatic urethra demonstrable on cystourethrography was associated with the diagnosis of obstruction on all the methods used. A diminished segment of the urethral lumen was associated with a high percentage of obstruction on all methods, the PURR showing the highest (100%). However, the diagnosis of constrictive obstruction was found in only 30% of the cases.