Nocturnal Penile Erections: The Role of RigiScan in the Diagnosis of Vascular Erectile Dysfunction


Ayman Elkholy, MD, Mansoura Faculty of Medicine, Department of Andrology, Mansoura University, Mansoura 35111, Egypt. Tel: +201117979899; Fax: +20502231191; E-mail:


Introduction.  To determine the etiology of cases with organic erectile dysfunction (ED), invasive techniques are needed that can induce patient anxiety and disturb test results.

Aim.  To find any special patterns of nocturnal penile tumescence and rigidity (NPTR) records in cases of vasculogenic impotence that can differentiate cases of arterial and venous origin without resorting to the more invasive diagnostic tests.

Methods.  This study included 95 cases of ED (77 cases with abnormal NPTR records plus 18 cases with normal NPTR). History taking and clinical examination with estimation of serum androgen hormones and postprandial blood glucose were done. All patients were then subjected to the following: NPTR monitoring using RigiScan device (Dacomed Corporation, Minneapolis, MN, USA), pharmacopenile duplex ultrasound examination, and redosing pharmacocavernosometry. According to the results of these tests, patients were classified into four groups: psychogenic, arteriogenic, venogenic, and combined arteriogenic–venogenic ED groups. Receiver operator characteristic (ROC) curve analysis of the different RigiScan parameters of venogenic group vs. the arteriogenic group was done. Best parameters were then retested by using them in prediction of veno-occlusive dysfunction (VOD) in all studied patients.

Main Outcome Measures.  Different RigiScan parameters: number of events, duration of best episode, base tumescence, base rigidity, tip tumescence, and tip rigidity.

Results.  RigiScan parameters were statistically lower in venogenic than in arteriogenic group and were more correlated with flow to maintain than the peak systolic velocity. ROC curve analysis showed that VOD can be predicted if the duration of the best event is <11.5 minutes (diagnostic accuracy 83.7%) or tip rigidity is <36.5% (diagnostic accuracy 81.6%). On generalizing these values in all patients, duration of best event showed diagnostic accuracy of 88.4%.

Conclusion.  VOD can be predicted if duration of the best event of NPTR monitoring is less than 11.5 minutes, but the presence of concomitant arterial dysfunction cannot be excluded. Elhanbly S and Elkholy A. Nocturnal penile erections: The role of RigiScan in the diagnosis of vascular erectile dysfunction. J Sex Med 2012;9:3219–3226.