Distance From Critical Pelvic Structures: Radiographic Comparison of High Submuscular and Space of Retzius IPP Reservoir Placement Techniques

Objective: To evaluate the distance from critical pelvic structures (CPS, defined as bladder and iliac vessels) among inflatable penile prosthesis (IPP) reservoirs placed into the space of Retzius (SOR) and high submuscular (HSM) locations using cross-sectional imaging. IPP reservoir placement into the HSM location has been proposed as a strategy to prevent injury due to greater distance from CPS. Methods: Our institutional database was retrospectively reviewed to identify men who underwent IPP insertion between 2007 and 2020 and had available cross-sectional abdominopelvic imaging after the time of surgery. Patients were grouped based on reservoir placement technique (SOR vs. HSM). Staff radiologists blinded to placement technique evaluated reservoir position to determine the shortest distance between CPS and the reservoir and if a mass effect was present on CPS. Variables were analyzed using chi-squared, Fisher's exact, and student's T-tests as indicated. Results: Among 1,010 IPP cases performed during the study interval, 139 (13%) were imaged. Compared with SOR reservoirs (n = 32), HSM reservoirs (n =107) were significantly less likely to induce a mass effect on the bladder (72 vs. 9%, P = <.01) or iliac vessels (34 vs. 4%, P = <.01) and were located roughly 5 times further from the bladder (10 ± 22 vs. 49 ± 36 mm, P = <.01) and iliac vessels (5 ± 9 vs. 23 ± 26 mm, P = <.01). Conclusion: This study radiographically confirms that IPP reservoirs are located significantly further away from CPS following HSM placement compared to SOR placement.