In according to the Petros and Ulmsten’s integral theory the stress urinary incontinence (SUI) is caused by either a combination of intrinsic sphincter deficiency (ISD) and urethral hypermobility. However, it caused by ISD alone is rare whereas urethral hypermobility occurs frequently without SUI. The aim of this study was to correlate the ISD assessed by urodynamic test  with the urethral hypermobility evaluated by trans labial ultrasound  in women with SUI.

This was a prospective study on women with SUI. The local ethics committee approved the study and all patients signed an informed consent document.We included women with pure  SUI and mixed urinary incontinence with predominant stress form. We excluded women with pelvic organ prolapse or with a history of anti incontinence surgery.They were evaluated by translabial ultrasound and urodynamic test. Ultrasound was performed by a 3.5-5 MHz curved array probe with the patient at rest and during a maximum Valsalva manoeuvre in the dorsal lithotomy position.The symphysis pubis, was used as a landmark to evaluate bladder neck position and mobility.To assess bladder neck mobility, we measured the distance between the bladder neck and the longitudinal axis of the symphysis. We recorded distances above and below the longitudinal axis of the symphysis as negative and positive respectively. The urodynamic test was done according to the ICS good pratice protocol. The VLPP ≤60 cm H2O was used as cut off for the diagnosis of ISD.We divided the patients into three groups:	1) VLPP≤60 cm H2O, 2) 60<VLPP≤90 cm H2O, 3) VLPP>90 cm H2O. All continuous variables were normally distributed. Associations between VLPP data and each of the continuous explanatory variables were summarized as Pearson’s correlation coefficients.We considered p < 0.05 to be statistically significant.

From December 2015 to March 2021, a total of 87 consecutive patients with SUI underwent urodynamic test as no baseline difference between groups in terms of clinical characteristics except for storage symptoms and urgency incontinence. The VLPP was compared to ultrasound data. There was no correlation between indices of hypermobility such as bladder neck descent on Valsalva and VLPP (VLPP ≤ 60, p=0.06; 60<VLPP ≤ 90, p=0.7; VLPP > 90, p=0.7). Funneling of the bladder neck on Valsalva manoeuvre was associated with a lower VLPP (VLPP<60) (p =0.026).

The lack of correlation between urodynamic parameters and ultrasound-assessed hypermobility could be explained by the pathophysiology of stress incontinence. Stress incontinence is caused by ISD which can be associated with urethral hypermobility, but not necessarily

It confirmed that hypermobility and the ISD are largely independent factors in the causation of genuine stress incontinence, even if damage may occur concomitantly