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J Urol. 1998 Jun;159(6):1921-6.

Nocturnal penile tumescence and rigidity monitoring in young potent volunteers: reproducibility, evaluation criteria and the effect of sexual intercourse.

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Department of Urology, School of Medicine, Aristotle University of Thessaloniki, Greece.



We studied the reproducibility of nocturnal penile tumescence, rigidity evaluation criteria and the possible effects of sexual intercourse in young, healthy, potent male volunteers.


We recruited 12 male medical students 21 to 24 years old into the study. A disorder-free medical history, availability of a sexual partner and normal erectile function were the inclusion criteria. All subjects completed 3 sessions of 3 nights of recording using the RigiScan* device with at least a 3-day interval between recordings. During the last 3-night recording subjects were asked to have sexual intercourse at least once. Analysis of the recordings was focused on the best erectile event as well as on rigidity and tumescence activity units normalized per hour.


The subjects completed 36, 3-night recordings. Of the total of 108 sessions 18 occurred after sexual intercourse. We analyzed 562 erectile episodes. All 3-night recordings included at least 1 episode of rigidity at the penile tip greater than 60% and more than 10 minutes in duration. Sexual intercourse did not significantly affect nocturnal penile tumescence and rigidity. When rigidity and tumescence activity unit values were normalized by the hour and expressed as mean values of the 3-night sessions, documented values became reproducible.


At least 2 consecutive nights of recording are necessary to evaluate nocturnal penile tumescence and rigidity recordings. Nocturnal penile tumescence and rigidity with at least 1 erectile episode of tip penile rigidity greater than 60% and 10 minutes in duration may be associated with potency. Mean rigidity and tumescence activity unit values per hour of a recording may be used as objective parameters to measure overall erectile activity. In addition, sexual intercourse seems to decrease nocturnal penile tumescence and rigidity measurements, although not statistically significant. We anticipate that application of these criteria for nocturnal penile tumescence and rigidity evaluation will improve the diagnostic validity of the test. Future research will determine whether these criteria are too strict for the evaluation of aging men.

[Indexed for MEDLINE]

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