Failure to attain stretched penile length after intracavernosal injection of a vasodilator agent is predictive of veno-occlusive dysfunction on penile duplex Doppler ultrasonography.

Penile duplex Doppler ultrasound (PDDU) assesses the etiology of erectile dysfunction. Peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) are common PDDU parameters. We assessed whether stretched penile length (SPL) in the flaccid state and measured penile length at peak erection after intracavernosal injection (ICI) of a vasodilator during PDDU correlated with the etiology of erectile dysfunction. We performed a retrospective review of 93 patients who underwent PDDU for erectile dysfunction. Normal and stretched penile length were measured, both at a flaccid state prior to ICI and at peak erection during PDDU. Collected data included patient demographics, vascular, and anatomic parameters. The mean age was 52 years. SPL was equivalent to peak penile length after ICI in 60 patients (65%, group 1) and did not match in 33 (35%, group 2). There were no significant differences between the two groups in terms of flaccid, stretched, and post-ICI erect penile lengths, IIEF score, PSV, percent rigidity or tumescence, and vasodilator dose used. Patients in group 2 had less of a change in penile length from flaccid to erect state (36% vs. 44%, p = 0.02), higher EDV (12.0 vs. 8.5, p = 0.041), lower RI (0.6 vs. 1.0, p = 0.046), and more veno-occlusive dysfunction (82% vs. 53%, p = 0.001). On multivariate analysis, failure to reach maximum SPL at peak ICI erection (OR 2.255, CI 1.191-4.271, p = 0.0126), EDV (OR 1.281, CI 1.115-1.471, p < 0.001) and RI (OR 0.694, CI 0.573-0.723, p = 0.009) predicted veno-occlusive dysfunction. Failure to reach maximal SPL during PDDU using ICI with a vasodilator agent predicted veno-occlusive dysfunction, which is independent of both penile rigidity and tumescence. This measurement could serve as another diagnostic tool for predicting veno-occlusive dysfunction when PDDU is not readily available. Limitations include the subjective nature of penile measurements and different PGE1 doses used.