A clinical view of pressure-flow studies.

Lower-urinary-tract symptoms might be due to bladder dysfunction, infravesical obstruction, or both, and these conditions give rise to the same type of symptoms. Classification of symptomatic benign prostatic hyperplasia (BPH) patients into obstructed or unobstructed cases can be done only by pressure-flow studies. This classification has been demonstrated to be of predictive value for the outcome of surgical treatment, both symptomatically and urodynamically. Pressure-flow studies are therefore helpful in the pretreatment workup of patients in regard to both diagnosing the underlying pathophysiology and, consequently, stratifying patients for different treatments or watchful waiting. Different methods of interpreting pressure-flow investigations share the same theoretical foundation and therefore have only minor differences in classifying patients into obstructed or unobstructed cases. The more advanced methods make a more differentiated classification possible, but these are currently mostly of theoretical value in research.