Correlation between urethral sphincter activity and Valsalva leak point pressure at different bladder distentions: revisiting the urethral pressure profile

Abstract

Purpose: We determined the correlation between Valsalva leak point pressure (LPP) and the urethral pressure profile (UPP) in urodynamically selected patients with stress urinary incontinence (SUI) as well as the interference of bladder volume on this correlation.

Materials and methods: A total of 450 consecutive women with SUI were clinically evaluated and underwent urodynamic study. Inclusion criteria were urodynamically demonstrable SUI with normal bladder compliance, sensitivity and capacity. Severe pelvic prolapse, detrusor overactivity and a pattern suggestive of obstruction were excluded. Urodynamic study was performed using a 7Fr 4 channel membrane catheter. LPP was determined at mid bladder capacity and UPP was determined at 50 ml, between 200 and 250 ml, and at bladder capacity.

Results: A total of 200 women fulfilled the selection criteria, of whom 30, 114 and 56 had a LPP of 60 or less, between 60 and 120, and greater than 120 cm H2O, respectively. Except for age and the number of pads the 3 groups were well matched in clinical and bladder urodynamic parameters. A progressive correlation of LPP with maximum urethral closure pressure was found when UPP was performed at 50 ml (r = 0.305, p <0.0001), at 250 ml (r = 0.483, p <0.0001) and at maximum bladder filling (r = 0.561, p <0.0001). Urethral functional length did not show a correlation with LPP at a bladder distention of 50 ml (r = 0.117, p = 0.100) or 200 ml (r = 0.167, p = 0.019) but there was a minor correlation at bladder capacity (r = 0.234, p = 0.002).

Conclusions: There is a significant correlation between maximum urethral closure pressure and LPP. Patients with a LPP of 60 cm H2O or less have a shorter urethral functional length and lower sphincter activity. Patients with SUI have a more remarkable correlation between UPP and Valsalva LPP when UPP is determined after filling the bladder to more than 200 ml.