Changes in penile length after radical prostatectomy: Investigation of the underlying anatomical mechanism

Objective: To measure changes in penile length (PL) over time before and after radical prostatectomy (RP), and to investigate the underlying mechanisms for these changes. Patients and Methods: The stretched PL (SPL) of 102 patients was measured before, 10 days after, and at 1, 3, 6, 9, 12, 18 and 24 months after RP. The perpendicular distance from the distal end of the membranous urethra to the midline of the pelvic outlet was measured on mid-sagittal magnetic resonance imaging (MRI) slice at three time points: preoperatively; 10 days after RP; and 12 months after RP. Pre- and postoperative SPLs were compared using paired Student's t-test. Predictors of PL shortening at 10 days and at 12 months after RP were evaluated on univariate and multivariate analyses. Results: The SPL was shortest 10 days after RP (mean PL shortening from preoperative level: 19.9 mm), and gradually recovered thereafter. SPL at 12 months after RP was not significantly different from preoperative SPL. On MRI examination, the distal end of membranous urethra was found to have moved proximally (mean proximal displacement: 3.9 mm) at 10 days after RP, and to have returned to the preoperative position at 12 months after RP. On univariate analysis, only the volume of the removed prostate was a predictor of SPL change at 10 days after surgery; on multivariate analysis, the association was not statistically significant. No predictor of SPL change was found at 12 months after RP. Conclusion: The SPL was shortest at 10 days after RP and gradually recovered thereafter in the present study. Anatomically, the glans and corpus spongiosum surrounding the urethra are an integral structure, and the proximal urethra is drawn into the pelvis during urethrovesical anastomosis. This is the first report showing that slight vertical repositioning of the membranous urethra after RP causes changes in SPL over time. These results can help inform patients about changes in penile appearance after RP. © 2017 BJU International.
Embargo Period 12 months