We evaluated spontaneous tumescence after penile prostheses implantation in a retrospective study. A total of 32 patients with three-piece hydraulic implants (17 Mentor Alpha I, 15 AMS Ultrex Plus) were enrolled. Consultation, personal interviews and questionnaires for both the patients and their partners provided the necessary information. The average follow-up period was 29 months. In total, 50 % of the patients reported spontaneous tumescence without activation of the implant and one further patient (3%) claimed full rigid spontaneous erections. General satisfaction with the prosthetic result was high at 91%. The following complications arose: one case of prosthesis infection, one case of mechanical failure, one case of cylinder dislocation and two cases of paraphimosis. A possible explanation for spontaneous tumescence after penile prosthesis implantation is the elevated preload of the compressed rather than destructed cavernous tissue. The artificial erection evoked by the prosthesis then takes the form of a normal physiological reaction and/or a good objective ridigity, and could account for the high patient satisfaction rate with three-piece hydraulic implants.

We conclude that sacral neuromodulation is an effective treatment option in patients with nonobstructive urinary retention. The carbachol test does not possess any definitive predictive value with respect to the success rate of sacral neuromodulation in patients with chronic urinary retention. The success rate more likely depends on the localisation of the nerve lesion. PNE tests should be performed in all patients with therapy resistent nonobstructive urinary retention, as no other predictive factors exist.