Correlation of penile and bulbospongiosus measurements: implications for artificial urinary sphincter cuff placement

Purpose: We assessed penile and bulbospongiosus measurements to develop a quantitative guide to select the surgical approach (perineal vs transscrotal vs transcorporeal) to artificial urinary sphincter cuff placement.

Materials and methods: We retrospectively reviewed the intraoperative records of 100 men who underwent artificial urinary sphincter placement (43) or anastomotic urethroplasty (57) from February 2008 to June 2009. Correlations between penile (stretched length and circumference at the shaft base) and bulbospongiosus (distal and proximal circumference) measurements were assessed. Cases were analyzed according to 2 penile circumference groups, including group 1-8.0 cm or less and group 2-8.5 or more.

Results: Mean proximal bulbospongiosus circumference was uniformly larger than distal bulbospongiosus circumference (4.5 vs 3.9 cm). It was about 50% of the penile shaft circumference (mean 8.9 cm, r = 0.70). In group 1 men the average distal bulbospongiosus circumference was 3.4 cm. They were more likely to undergo transcorporeal artificial urinary sphincter cuff placement than those in group 2, who had an average distal bulbospongiosus circumference of 4.1 cm (8 of 22 or 36% vs 1 of 21 or 5%, OR 11.4). Penile length correlated less robustly with distal and proximal bulbospongiosus circumference (r = 0.39 and 0.43, respectively). Patients with urethroplasty had significantly larger urethral measurements than those with the artificial urinary sphincter (proximal and distal bulbospongiosus circumference 4.9 vs 3.7 and 4.1 vs 3.2, respectively) but were significantly younger (47 vs 67 years), and less likely to have erectile dysfunction (11 of 57 vs 34 of 43) or to have undergone radical prostatectomy (0 of 57 vs 37 of 43).

Conclusions: Bulbospongiosus circumference appears to be proportional to penile circumference. The distal bulbospongiosus is uniformly smaller than the proximal bulbospongiosus. The potential need for a perineal or transcorporeal approach to artificial urinary sphincter placement can be anticipated by penile circumference measurements and a combination of clinical factors, such as older patient age, history of radical prostatectomy and impotence.