Prevalence of Radiographic Misinterpretation of Urethral Bulking Agents

Objectives: Urethral bulking agents, used as a minimally invasive management option for patients with stress urinary incontinence, can be mistaken for urethral or periurethral pathology on imaging. This misinterpretation can cause significant anxiety to patients or lead to unnecessary intervention. We aim to characterize radiologic interpretation of urethral bulking agents in patients who underwent subsequent computed tomography of the abdomen and pelvis (CTAP) imaging and patient response to these interpretations.

Methods: All patients who underwent placement of a urethral bulking agent from January 2011 to March 2024 were identified in the electronic medical record using Current Procedural Terminology (CPT) code 51715. All charts were reviewed to identify the subset of patients who underwent subsequent CTAP. The radiologic interpretations were reviewed to assess for accuracy in identification of the urethral bulking agent. Patient communications recorded in the electronic medical record regarding imaging results were also reviewed.

Results: One hundred forty-four patients underwent injection of a urethral bulking agent during the study period. Of those, 31 patients had at least one CTAP performed following injection, leading to a total of 61 CTAPs. Timing of CTAP after injection of urethral bulking agent ranged from 1.1 to 85.8 months, with an average of 25.7 months. The urethral bulking agent was accurately identified in only 15 (24.6%) scans. Of the remaining imaging, the presence of the urethral bulking agent was not noted in 31 (50.8%) scans. However, on review of the imaging by one of the authors (JM), only one did not have identifiable urethral bulking agent present. The urethral bulking agent was noted but inaccurately characterized in the remaining 15 (24.6%) scans. When noted, the most common radiologic interpretations of the urethral bulking agent were seven bladder stones (15.6%), six nonspecific calcifications (13.3%), one radiodense material (2.2%), and one urethral stone (2.2%). Findings are summarized in Table 1. Representative image of urethral bulking agent (identified with yellow arrow) seen on CTAP is shown in Figure 1. Of the eight patients in whom a urolith (bladder stone or urethral stone) was noted radiographically, two sent messages via the electronic medical record with questions about the findings. One patient expressed anxiety regarding the finding and requested treatment recommendations.

Conclusions: Urethral bulking agents are often inaccurately interpreted on CTAP and are only correctly identified a minority of the time. In addition to misinterpretation potentially resulting in unnecessary intervention, this can also cause anxiety for patients. These findings highlight the importance of clearly communicating to patients that their bulking agent may be detected by subsequent imaging and possibly incorrectly characterized.