Hypothesis / aims of study
Urinary incontinence (UI) is a common side effect of radical prostatectomy (RP), significantly affecting quality of life. Membranous urethral length (MUL), measured by magnetic resonance imaging (MRI), is an anatomical factor associated with continence recovery. In recent years, transperineal ultrasound (TPUS) has emerged as an accessible alternative, capable of providing dynamic measurements of pelvic floor anatomical structures. The aim of this study was to measure static and dynamic anatomical variables of the pelvic floor using TPUS and to analyze their relationship with postoperative UI.
Study design, materials and methods
A prospective comparative study was conducted with consecutive sampling of patients with low- or intermediate-risk prostate cancer who underwent RP at Virgen del Rocío Hospital between 2022 and 2024. All patients were assessed preoperatively by TPUS using a standardized protocol. Static anatomical variables (MUL, urethrovesical junction [UVJ], and prostatic height) and dynamic variables (UVJ mobility during Valsalva and urethroprostatic angle [UPA]) were measured. Urinary function was evaluated using the validated ICIQ-SF questionnaire at 1, 3, 6, and 12 months after surgery. Anatomical variables were compared between continent and incontinent patient groups. Statistical analysis was performed using SPSS v29, including mean comparison tests, multivariate analysis, and ROC curves to determine clinically relevant cut-off points
Results
A total of 34 patients were included. Men who regained continence showed higher mean UVJ values (39.1 mm vs 30.1 mm; p = 0.007), greater UVJ mobility during Valsalva (6.98 mm vs 2.33 mm; p = 0.050), and greater prostatic height (42.22 mm vs 36.13 mm; p = 0.026) compared with incontinent patients. MUL was slightly greater in continent patients (12.5 mm vs 11.38 mm), although these findings were not statistically significant. At 6 months, a statistically significant association was observed between UPA and continence (p = 0.001), identifying it as a protective factor (OR = 0.86 for each degree of increase). ROC curves established relevant cut-off points for predicting continence: MUL during Valsalva < 6.7 mm, UVJ < 22.4 mm, and UPA < 129.3.
Interpretation of results
Our findings suggest that TPUS allows a functional anatomical characterization of the male pelvic floor with predictive value for continence recovery after RP. UVJ mobility, UPA, and static UVJ may indirectly reflect the integrity of the sphincter complex and its ability to respond to strain. MUL, despite its value in previous MRI-based studies, showed lower discriminatory capacity when measured by ultrasound. TPUS offers advantages such as low cost, absence of radiation, and the possibility of dynamic assessment, making it a useful tool in preoperative functional evaluation