Urodynamics in benign prostatic hyperplasia (BPH)

Abstract

The simple pathophysiological concept of clinical BPH with a causal relationship between hyperplasia, obstruction, and specific symptoms does not hold up after a critical evaluation. The voiding function can nowadays be investigated comprehensively and differentiated utilizing modern urodynamic methods, and the function of the bladder outlet and the detrusor muscle can be evaluated quantitatively. Obstruction as a central term in clinical BPH can therefore be objectively documented. It can be shown that in a significant proportion of patients admitted for TURP with hyperplasia and symptoms of prostatism, no obstruction is present (over one-fourth of patients). The success rate of TURP in non-obstructed patients is worse than in obstructed patients; however, the subjective assessment of the surgical success is positive in the majority of patients. This holds true in a similar way for alternative treatment modalities (drug, balloon dilation, thermotherapy) after which the symptomatic success apparently is not associated with an objective reduction in obstruction. This lack of a definite correlation between symptoms and obstruction in BPH is open to many different interpretations. It is generally accepted that BPH without symptoms and obstruction or with obstruction but without symptoms may occur. It is, however, also true that aside from the highly selected patient population in this study with hyperplasia and symptoms and (suspected) obstruction, no data are available since urodynamic studies in patients with BPH but without symptoms are for obvious reasons not available. If we limit our thoughts to the few clear facts, it becomes evident that modern urodynamic methods can clearly distinguish between obstructive and non-obstructive symptomatic BPH. This introduces a new important standard of quality into BPH research requiring reassessment of currently available data. The simple urodynamics utilizing a flow rate recording as a convenient non-invasive diagnostic test is in widespread use and finds its proper place in the quick but non-specific documentation of bladder emptying function in clinical practice. Firm conclusions concerning the cause of a disturbed bladder emptying function are, however, not contained within the flow rate recording and can therefore not be abstracted from even the most refined methods to analyze the flow rate recording. The all-important parameter without which obstruction cannot be judged is the detrusor pressure during micturition. Since urodynamic pressure measurements are currently only possible as an invasive test, the indication for combined pressure flow measurements has to be considered carefully and the recording itself has to be conducted with appropriate expertise.(ABSTRACT TRUNCATED AT 400 WORDS)