• erectile dysfunction;
  • penile length;
  • radical prostatectomy;
  • prostate cancer;
  • penile rehabilitation


  • To assess the impact of radical prostatectomy (RP) on penile dimensions.
  • To assess the impact of phosphodiesterase-5 inhibitor (PDE5i) use on penile length changes.

Patients and Methods

  • Men undergoing RP were enrolled in this prospective study before surgery. Demographic, clinical and PDE5i frequency-of-use data were collected.
  • Erectile function was measured using the erectile function domain (EFD) of the International Index of Erectile Function.
  • A single evaluator measured stretched flaccid penile length (SFPL) before RP, and at 2 and 6 months after RP.
  • Repeated measures analysis was used to test differences in SFPL between timepoints. Pearson correlation was used for univariate analyses and multiple regression was used for multivariable analysis.


  • A total of 118 patients were evaluated at baseline, with 76 and 63 patients evaluated at 2 and 6 months, respectively.
  • At 2 months, there was a 2.4-mm mean decrease in SFPL, while at 6 months there was no significant difference.
  • At 6 months, those subjects who took a daily PDE5i had no SFPL loss (n = 36, 1±6.7 mm gain, P = 0.37 compared with baseline), while those subjects who did not consistently take a PDE5i had SFPL loss (n = 27, 4.4±6.6 mm loss, P < 0.002 compared with baseline).
  • In multivariable analysis, PDE5i use at 6 months and 6-month EFD score without on-demand PDE5i were significant predictors of 6-month SFPL loss, suggesting that an increase in these variables leads to SFPL preservation.


  • In this rigorously conducted prospective study of SFPL changes after RP, there was evidence of SFPL loss at 2 months, but not at 6 months after RP.
  • PDE5i use moderated SFPL loss, with patients who regularly used PDE5i having no loss in SFPL.