[Comparison between nocturnal penile tumescence (NPT) and artificial full erection]

Recording of nocturnal penile tumescence (NPT) is useful for the objective diagnosis of impotence. However, criteria for evaluating obtained results have not been firmly established. Since the increase in the penile circumference varies among individuals, differential diagnosis based on only certain changes in the circumference during NPT is difficult. Therefore, we infused heparinized saline into the corpora cavernosa to induce artificial full erection (AFE), and the increase in the penile circumference was compared with that during NPT. In all controls with normal ability to attain erection, the percentage of the increase in the penile circumference during NPT to that with AFE (NPT/AFE) was 80% or more. In 27 patients with impotence, an NPT/AFE of 80% or more was observed in 14 patients, 11 of whom had no particular organic factors for impotence. Eleven patients had an NPT/AFE of less than 60%, 9 of them had apparent organic factors and the remaining 2 had abnormal PBPI. Patients showing less than a 10 mm increase in the penile circumference during NPT could be diagnosed with organic impotence. However, in those with an increase of 10 mm or more during NPT, a differential diagnosis was difficult to make, and the comparison with AFE seemed to be a useful method. Therefore, AFE which requires no special equipment and is a simple and safe procedure, can be a valuable adjunctive examination in assessing NPT.