The penile cuff test: A clinically useful non-invasive urodynamic investigation to diagnose men with lower urinary tract symptoms

Abstract

Objectives: To summarize the development of a novel non-invasive test to categorize voiding dysfunction in men complaining of lower urinary tract symptoms (LUTS) - the penile cuff test.

Methods: The test involves the controlled inflation of a penile cuff during micturition to interrupt voiding and hence estimate isovolumetric bladder pressure (p(ves.isv)). The validity, reliability, and clinical usefulness of the test were determined in a number of studies in men with LUTS.

Results: The penile cuff test can be successfully performed in over 90% of men with LUTS. The reading of cuff pressure at flow interruption (p(cuff.int)) gives a valid and reliable estimate of invasively-measured p(ves.isv) and when combined with the reading for maximum flow rate obtained during the test (Q(max)) produces an accurate categorization of bladder outlet obstruction (BOO). Use of this categorization prior to treatment allows improved prediction of outcome from prostatectomy.

Conclusion: The penile cuff test fulfils the criteria as a useful clinical measurement technique applicable to the diagnosis and treatment planning of men with LUTS.

Keywords: Bladder outlet obstruction; non-invasive urodynamics; urinary symptoms.

Figure 1

Diagrammatic representation of the penile cuff test. Cuff inflation continues until flow ceases or a safety cut-off of 200 cmH₂O is reached. Following flow arrest, the cuff is deflated producing the characteristic surge in flow rate.

Figure 2

Comparison of cuff interruption pressure and directly measured isovolumetric bladder pressure in a large-scale clinical evaluation illustrating the overestimation of approximately 15 cmH₂O. Each point represents readings of isovolumetric bladder pressure (p_ves.isv) and cuff pressure at interruption of flow (p_cuff.int) measured simultaneously in 151 men with LUTS

Figure 3

Pressure (p_cuff.int) and urine flow (Q_max) readings obtained using the penile cuff test from 144 men with LUTS plotted on the proposed non-invasive nomogram. Symbols represent categorization using conventional invasive PFS (· = obstructed, Δ = equivocal,  = unobstructed). The non-invasive nomogram is divided into 4 quadrants by an oblique line (pcuffint = 80 + 4Q_max) and a vertical line (Q_max = 10) to categorize individual plots as obstructed (upper left), non obstructed (lower right) or diagnosis uncertain (lower left and upper right).

Figure 4

Bladder pressure and urine flow readings obtained with the non-invasive penile cuff test from 149 prior to TURP (A) and 4 months following TURP (B) plotted on the non-invasive nomogram. A marked movement of individual plots from the upper left obstructed area of the nomogram to the lower right not obstructed area is seen.

Figure 5

Reproduction of output from an individual penile cuff test showing the pressure flow plot (A) and the resultant readings plotted on the non-invasive nomogram

Figure 5B

(B) categorizing the void as obstructed