Isometric detrusor pressure in the male patient: a comparison between voluntary urethral sphincter contraction and...

Different functions of detrusor contraction are estimated by measurement of maximum isometric detrusor pressure with voluntary urethral sphincter contraction and forced penile compression flow-stop techniques. Maximum isometric pressure curves with these 2 techniques consist of 2 and 3 phases, respectively. The first phase of each method is a linearly increasing curve whose slope seems to indicate the speed of isometric detrusor contractions. The second phase in the curve obtained by the voluntary flow-stop technique is considered to be an inhibitory phase, while that obtained by the forced technique is considered to be a continuing phase followed by a plateau, the third phase. The maximum isometric pressures obtained with the forced flow-stop technique were statistically higher than those obtained with the voluntary flow-stop technique in patients with enuresis and prostatic obstruction. Although in volunteers the maximum isometric pressure measured with the forced flow-stop technique showed higher values than that measured with the voluntary method there was no statistical difference. There was no statistical difference in the speed of detrusor contractions obtained with either technique in all of the patients except those with urethral stricture, in whom the speed of detrusor contraction measured with the forced flow-stop technique showed a lower value than that obtained with the voluntary method. We believe that the penile urethra distal to the stricture acts as a reservoir when urinary flow is poor. The forced flow-stop technique was necessary to measure maximum isometric pressure in patients with neurogenic bladder dysfunction, many of whom could not stop urinary flow voluntarily.