Correlations between sonographic and urodynamic findings after mid-urethral sling surgery

PURPOSE: To study correlations between sonographic and urodynamic findings after suburethral sling surgery. METHODS: This is a retrospective study on 141 women who had multichannel urodynamic testing and translabial 4D ultrasound after suburethral sling surgery between 2006 and 2016. The sling-pubis gap, i.e., the distance between sling and infero-posterior margin of the pubic symphysis on Valsalva, and urethral motion profile were determined. The urethral motion profile was assessed by calculating the mobility vectors of 6 equidistant points along the length of urethra from bladder neck to external urethral meatus, against the dorsocaudal margin of the symphysis pubis on Valsalva. Correlations between sling-pubis gap and mobility vectors, and between these measures and urodynamic data were determined. RESULTS: The median follow-up interval of 126 women with complete data sets was 36 months. Significant correlations were found between the sling-pubis gap and mid-urethrall mobility vectors (all P<0.02). Both sling-pubis gap and mid-urethrall mobility vectors were negatively correlated with detrusor pressure at maximum flow (P=0.037 and P=0.004). Urodynamic Stress Incontinence was more likely in women with a higher sling-pubis gap (P=0.003). CONCLUSIONS: The tighter the sling on ultrasound, the less likely is urodynamic stress incontinence, and the higher is detrusor pressure on voiding.