Parameters of erection.

Passive erection was obtained in 10 patients with normal erections without the use of any artificial mechanism of retention at the base of the penis. The necessary flow to provoke the erection ranged between 80 and 120 ml/min. Intracavernous pressure and penile circumference were also monitored until the appearance of a complete erection. This study showed that the maximum tumescent diameter of the penis was obtained before significant rigidity and thus explains the possible misinterpretation of nocturnal penile tumescence as a screening method for impotence.