Comparison of radiographic and sonographic urethrography for assessing urethral strictures

The aim of this study was to compare radiourethrography (RUG) and sonourethrography (SUG) for assessment of urethral strictures and to evaluate whether RUG underestimates stricture length, as has been reported. Fifty-one men with suspected urethral strictures were evaluated by both methods performed consecutively. Stricture lengths and diameters measured by RUG were significantly greater (mean 22%, 30%) than those measured by SUG because of radiographic magnification. Both methods, however, detected a similar percentage lumen reduction and similarly graded stricture severity. Equally significant non-correlation between both methods for length measurements in the bulbar and penile urethra (p<0.001, R²=0.33 and 0.34, respectively) supported radiographic magnification. Previous inaccuracies appear to relate to RUG measurements of the central tight stricture (mean 44% of the entire length in our series), not the full stricture length. Use of sonographic contrast medium intra-urethrally improved the definition of long narrow strictures. The SUG gave information about peri-urethral tissues not provided by RUG. Once radiographic magnification was taken into account, there were no major differences in the assessment of urethral strictures by both methods. With correct measurement methods, RUG does not underestimate stricture length. For full assessment, the combination of RUG and SUG, which gives information about peri-urethral disease, is optimal in many patients.