To analyze the characteristics of forensic identification cases and evaluate the importance of integrating penile erection length, angle, and rigidity in diagnosing erectile dysfunction (ED).

Retrospective analysis of the forensic identification cases between Jan 2009 and May 2013. Correlation between ED diagnosis and nocturnal penile tumescence (NPT) test result or the site of injury was analyzed.

In total, 148 patients came for forensic identification of sexual function because of rape charges, divorce, medical accidents, or injury: 126 of 148 (85.1%) because of injury, of which 95 (75.4%) resulted from traffic accidents. There was a significant correlation between the site of injury and ED diagnosis; pelvic fracture with urethral or perineum injury was the most common. Our data showed that ED diagnosis was in general significantly associated with NPT results. However, we also identified three cases of diagnosed organic ED with normal NPT reactions. Our analyses showed that abnormal length and/or angle of the erectile penis were contributing factors to the diagnoses in these cases.

In addition to NPT test, which measures the rigidity of the erectile penis, the length and angle of the erectile penis should also be considered in diagnosing ED, particularly in the case of forensic identification of sexual function.