RESUMO
We analyzed the practical problems and factors which affect making the correct differential diagnosis in the interpretation or test results from the nocturnal penile tumescence (NPT) test and erotic stimulation test (EST). This was done to provide better information for higher diagnostic accuracy in the clinical application of these tests. The followings are the results of NPT tests and EST identifying the factors affecting correct differential diagnosis by comparison the other differential diagnostic methods. The overall sensitivity of NPT test (Number: 114 total patients) was 82%. 21 cases (18%) could not be diagnosed correctly due to traction of the sensor (12 cases, 10%) and sleep disturbance (9 cases, 8%). The overall sensitivity of EST (Number: 174 total patients) without considering the degree of patient`s sexual drive to erotic stimulation was 77%. 40 cases (23%) could not be diagnosed correctly due to tolerance to pornographic film (17 cases, 10 %), discomfort by the body attachments (14 cases, 8%) and traction of the sensor (9 cases, 5%). However, higher sensitivity (90%) and lower rate of incorrect diagnosis (10% ) were observed in 119 patients who showed Grade II or III (moderate to good) sexual drive to erotic stimulation. The results suggest that undesirable factors in the primary screening methods, traction of sensor, sleep disturbance in NPT test, and tolerance to pornographic film, discomfort by the body attachments, traction of sensor in EST must be taken into consideration when interpretation of test results is being performed.