COMPARISON OF DUPLEX ULTRASONOGRAPHY AND NOCTURNAL PENILE TUMESCENCE IN EVALUATION OF IMPOTENCE

Duplex ultrasound is used commonly to evaluate vascular function in im potent men. There is evidence, however, that some men with normal vasc ular function may have falsely abnormal duplex ultrasound results beca use of suppression of response to pharmacological stimulation due to a nxiety. We performed a prospective blinded study of 40 impotent men co mparing duplex ultrasound to a formal nocturnal penile tumescence eval uation. Duplex ultrasound was done with a standard 10 MHz. color Doppl er unit after intracorporeal pharmacological stimulation. Nocturnal pe nile tumescence was performed at a sleep laboratory, and included meas urements of penile circumference, axial rigidity, arterial pulsations, and direct patient and observer evaluation of erections. Of 40 men 20 had an abnormal duplex ultrasound result (maximum arterial velocity l ess than 30 cm. per second), including 9 who had normal nocturnal peni le tumescence with at least 1 rigid erection (greater than 550 gm. axi al rigidity) lasting at least 5 minutes. All 9 men had evidence of psy chogenic dysfunction on history and personality inventory, and only 1 had evidence of vascular disease. Of the other 11 patients with abnorm al duplex ultrasound and nocturnal penile tumescence findings, only 2 had evidence of psychogenic impotence and 9 had evidence of vascular d isease. In these 11 men there were significant correlations between ma ximum arterial velocity on duplex ultrasound, and maximum rigidity and arterial pulsations on nocturnal penile tumescence. Of 40 patients 20 had a normal duplex ultrasound finding (maximum velocity greater than 30 cm. per second). Nine of these patients had a normal nocturnal pen ile tumescence test, of whom 5 had evidence of psychogenic impotence a nd only 1 had evidence of vascular disease. Eleven men with normal dup lex ultrasound had an abnormal nocturnal penile tumescence test, inclu ding only 2 with any evidence of psychogenic impotence, while 9 had va scular disease and 1 had a history of neurological disease. Based on t his study 9 of 14 men (64%) with a normal nocturnal penile tumescence test and other evidence of psychogenic impotence had abnormal duplex u ltrasound. Therefore, an abnormal duplex ultrasound study should be in terpreted cautiously if there is evidence of psychogenic impotence. In men with vasculogenic impotence there is an excellent correlation and cross-validation between maximum velocity on duplex ultrasound, and a xial rigidity and arterial pulsations on nocturnal penile tumescence.