Penile elongation: a method for the screening of impotence

Circumferentially assessed penile responses less than 10 per cent of maximal tumescence usually are regarded as random variation. However, several investigators have hypothesized that one of the initial responses to sexual stimulation is a lengthening of the penile shaft. Circumferential measurements detect this lengthening as a decrease in penile circumference. Two experiments were conducted to investigate this hypothesis. During the first experiment penile circumference changes were monitored at 2 levels of voltage sensitivity. A reliable voltage decrease was observed for all subjects immediately after the introduction of an erotic stimulus. In the second experiment the penis was videotaped to determine the magnitude of penile lengthening that occurred during the circumferential decrease. The results indicated that a substantial penile length change occurred (mean 34.5 per cent of the total erection length change) before any diameter increase was evident. A small number of impotent patients with a clear etiology were investigated using this new test. The results suggest that penile elongation occurs in the absence of full erections in patients with psychogenic impotence, while circumferential and longitudinal changes do not appear after visual erotic stimuli in organically impotent patients. The penile elongation test may prove useful in the etiological screening of impotent patients.