[Maximum increase of penile circumference as a parameter for evaluation of penile erectile capacity].

PURPOSE

Male erectile capacity has been often evaluated with the maximum changes of penile circumference during nocturnal penile tumescence (NPT) by erectometer. However, it has not been fully established that the changes actually reflect penile rigidity. In this paper, we evaluated how the maximum change (the increase in circumference or its rate) of the circumference is related to penile rigidity.

PATIENTS AND METHODS

The study included 116 men with or without complaints of sexual dysfunction. The maximum increase (penile circumference on erection-that when flaccid) and increase rate ¿(penile circumference on erection-that when flaccid)/penile circumference when flaccid¿ of penile circumference and penile rigidity were studied during artificial erection induced by intracavernous injection of vasoactivedrugs.

RESULTS

When the maximum increase of penile circumference on erection was 21 mm or more, more than 80% of men achieved adequate rigidity of the penile for vaginal penetration. However, if the increase was 10 mm or less, all men had poor rigidity. In men having an increase of 11 mm or more and less than 21 mm, more than 80% did not achieve adequate rigidity if their penile circumference in the flaccid state was less than 95 mm. In contrast, 80% or more of the men showed penile rigidity sufficient for vaginal penetration when the flaccid circumference was 95 mm or more. Studies on the maximum increase rate revealed results similar to those in the study on the maximum increase. These two parameters had a similar diagnostic accuracy for evaluating penile rigidity.

CONCLUSIONS

A higher prediction rate for penile rigidity was achieved by adding the parameter of penile circumference in the flaccid state to the maximum increase or increase rate of penile circumference. Thus, evaluation of erectile capacity by maximum changes (the increase in circumference or its rate) of penile circumference with an erectometer can be used for screening of men with sexual dysfunction.