Griffiths CJ et al. (2005) A nomogram to classify men with lower urinary tract symptoms using urine flow and noninvasive measurement of bladder pressure. J Urol 174: 1323–1326

There is currently a need for a reliable, noninvasive method for measuring bladder pressure that could be used to assess bladder outflow obstruction in men with lower urinary tract symptoms (LUTS). One such method involving the controlled inflation of a penile cuff during voiding has been described and validated by Griffiths and colleagues, and in this new study the authors set out to determine whether the technique could be used to classify outlet status in men with LUTS.

The International Continence Society pressure–flow nomogram was modified to reflect the use of the noninvasive cuff measurement rather than the 'gold-standard' invasive method. This new nomogram was then evaluated by sequentially comparing both the invasive and noninvasive techniques in 144 men with LUTS. Overall there was agreement in the results of the two methods. The positive predictive value of the modified nomogram was 68%. Adding in the second criterion of obstruction (urine flow <10 ml/sec) improved diagnostic accuracy. In this case, 69% of the cases examined could be classified as either obstructed (positive predictive value 88%) or nonobstructed (negative predictive value 86%). Results for the remaining 31% of patients lay in the upper right and lower left of the nomogram, and classification was uncertain.

Prospective clinical studies are currently underway to assess the clinical usefulness of the modified nomogram in relation to outcome following prostatectomy.