Noninvasive methods of diagnosing bladder outlet obstruction in men. Part 1: Nonurodynamic approach

Purpose: Many methods have been suggested for diagnosing bladder outlet obstruction, as defined by the gold standard of pressure flow studies. Difficulty arises when comparing completely different methods of diagnosing bladder outlet obstruction. A comprehensive review of the literature of the different methods used to diagnose bladder outlet obstruction by noninvasive means was performed with a view to allow such a comparison. Materials and Methods: A MEDLINE search was done of the published literature covering until the end of 2004 on noninvasive methods used to diagnose bladder outlet obstruction. A direct comparison of all different methods was made using the sensitivity and specificity, positive predictive value and likelihood ratio of each test. For many of the techniques these values were calculated from the data presented in the article. Results: A multitude of methods has been applied to diagnose bladder outlet obstruction. Broadly the methods were divided into nonurodynamic and noninvasive urodynamic methods. Nonurodynamic methods include symptoms, biochemical tests such as prostate specific antigen, ultrasound derived measurements such as post-void residual urine, bladder weight, prostate configuration and size, intravesical prostatic protrusion and the Doppler resistive index. Part I of the review explores and discusses the relative merits of the nonurodynamic based methods. Conclusions: Ultrasound derived measures such as bladder wall thickness and bladder weight offer a promising possibility of diagnosing bladder outlet obstruction noninvasively. However, further reproducibility and large accuracy studies with better methodological standards are required before they can replace pressure flow studies.