Synchronous Cystosphincterometry Using an Air‐Filled Catheter for Assessing Detrusor‐External Sphincter Coordination: Preliminary Feasibility With Fluoroscopic Correlation

OBJECTIVE: To describe an air-filled catheter (AFC)-based technique for synchronous cystosphincterometry and to preliminarily evaluate its technical feasibility and fluoroscopic correlation for assessing detrusor-external sphincter coordination during voiding. This study also explored whether this simplified pressure-based method could provide a practical adjunctive assessment option in urodynamic laboratories where fluoroscopy or external urethral sphincter electromyography is unavailable. METHODS: This single-center retrospective methodological feasibility study included patients who underwent clinically indicated video urodynamic studies between July 2024 and March 2025. A 7-Fr air-filled dual-balloon catheter was used to record vesical pressure and urethral pressure at the external sphincteric urethra. Detrusor pressure and sphincteric urethral pressure were recorded simultaneously during filling and voiding. Voiding-phase fluoroscopic images were reviewed as contemporaneous anatomical correlation for pressure-based interpretation. Feasibility outcomes included technical completion, interpretability of pressure recordings, suspected catheter displacement, premature termination, and procedure-related adverse events. Findings were analyzed descriptively. RESULTS: A total of 32 patients were included in the analysis. The cohort included 3 males and 29 females, with a mean age of 32.6 years; range, 18-68 years. One patient had a sacral spinal cord injury, whereas the remaining patients had no documented neurological disorder. Synchronous bladder-urethral pressure measurement was completed in all 32 patients, with no premature termination or procedure-related adverse events. During voiding, four pressure-fluoroscopy patterns were identified: impaired external sphincter relaxation during detrusor contraction in 12 patients; preserved sphincter relaxation with effective voiding in 6 patients; preserved sphincter relaxation with detrusor contraction but no urine flow, suggesting non-sphincteric outlet obstruction in 4 patients; and sphincter relaxation without evident detrusor contraction, suggesting detrusor underactivity or functional inhibition in 8 patients. Two recordings showed an unexpectedly low urethral pressure pattern during filling, suggesting probable catheter displacement. CONCLUSIONS: Air-filled catheter-based synchronous cystosphincterometry was technically feasible in this preliminary single-center experience and allowed real-time characterization of detrusor-external sphincter pressure relationships. Fluoroscopic correlation supported the anatomical plausibility of pressure-defined sphincteric relaxation and non-relaxation patterns. Therefore, this method may provide a simplified adjunctive pressure-based assessment tool for evaluating detrusor-external sphincter coordination, particularly in centers where fluoroscopy or external urethral sphincter electromyography is unavailable. However, prospective studies with standardized feasibility metrics, reproducibility assessment, and direct comparison with established reference standards are required before its independent diagnostic accuracy can be defined.