Objective To compare suprapubic and transurethral 60% of men were in the same LPURR class with either method. Using the transurethral method, 26% of methods of measuring intravesical pressure in a group of men undergoing investigation for lower urinary patients increased the LPURR class by one and 6% by two classes. Using the Abrams-GriÃths nomogram, tract symptoms (LUTS), to identify which urodynamic variables are aÂected by the presence of an urethral 17% moved from a classification of equivocal to obstructed and 3% from unobstructed to equivocal. catheter during the voiding phase, and consequently whether there is any change in the grading of bladder Using the criterion of a value of URA >29, 57% were obstructed using the suprapubic and 74% using the outflow obstruction (BOO) using the commonly recognised grading systems.transurethral method. Conclusion According to the method used, there were Patients and methods Thirty-five men with LUTS underwent both suprapubic and transurethral pressure-flow diÂerences in the classification of obstruction between the suprapubic and transurethral routes; transurethral studies during a single session. Standard pressure flow variables were measured in all patients with both studies tended to indicate greater obstruction. The interpretation of urodynamic studies should take into methods, enabling calculation of obstruction using the commonly used grading systems, i.e. the Abramsaccount the technique used and where the route is transurethral, the smallest catheter available should GriÃth number, linear passive urethral resistance ratio (LPURR) and urethral resistance algorithm (URA).be used.