Correlation between urodynamics and perineal ultrasound in female patients with urinary incontinence

Aims: We performed urodynamics and perineal ultrasound in female patients with urinary incontinence to assess morphology and function of the bladder base-urethra complex and of the detrusor muscle, and to find the correlation between these investigations in the diagnosis of (a) bladder neck and urethral hypermobility and (b) detrusor overactivity; we wanted to compare the tolerabililty of the urodynamic investigation and of the perineal ultrasound.

Methods: We considered 66 female patients referred to our outpatient clinic for urinary incontinence; we also studied 14 healthy control patients. After accurate case-history collection and physical examination, urodynamic investigation and perineal ultrasound were performed, with recording of parameters specific to both investigations. The statistical analysis was performed by ANOVA, Bonferroni post hoc test, and Spearman correlation test. The tolerability index between the diagnostic investigations performed was assessed by a 3-point scale suggested by the patient.

Results: In patients with stress incontinence the posterior urethro-vesical angle, the angle of urethral inclination, and the proximal pubo-urethral distance are significantly different under stress compared to the resting phase; in patients with urge incontinence, the detrusor wall is thicker and is accompanied by an increase in opening detrusor pressure and detrusor pressure at maximum flow; it is also accompanied by detrusor overactivity with increased urethral functional length. Increased urethral functional length is suggested on axial US images by alteration of its normal characteristic target-like appearance with four concentric rings of different echogenicity. In all cases the tolerability of perineal ultrasound has been higher than that of urodynamics.

Conclusions: There is a good correlation between urodynamic and perineal ultrasound in the diagnosis of bladder neck and urethral hypermobility; perineal ultrasound can also be useful in the diagnosis of urge incontinence. Functional compressive urethral obstruction can be diagnosed on the basis of the ultrasound aspect of the urethral sphincter.