Materials and Methods: A total of 20 consecutive patients with erectile dysfunction underwent 2 sessions under real-time RigiScan* recording of penile erection. Session 1 consisted of adaptation in 10 minutes, intracavernous injection of 10 mu g. alprostadil in 10 minutes and re-dosing of 10 mu g. alprostadil in 10 minutes. Session 2 consisted of adaptation in 10 minutes, injection of 10 mu g. alprostadil in 10 minutes and genital plus audiovisual sexual stimulation in 10 minutes. The total duration of each session was 30 minutes. The order of the 2 sessions was randomly assigned with a week interval between each session.

Results: Re-dosing and genital plus audiovisual sexual stimulation caused a significant increase in erectile response compared to the result seen after the first injection (re-dosing p < 0.05, injection plus stimulation p < 0.01). However, erectile response after the genital stimulation session was significantly greater than that after re-dosing (p < 0.01). An erection comparable to the greatest spontaneous erection reported by the patient was much more frequently achieved after genital stimulation than after the re-dosing session (p < 0.01).

Conclusions: The combination of injection and stimulation caused a significantly greater erectile response than re-dosing. We suggest that the former should always be used during color Doppler sonography to optimize the accuracy of the test. Re-dosing is suggested when an incomplete erectile response occurs after the injection plus stimulation phase.