The role of ultrasound in the investigation of stress urinary incontinence is important, both in the pre-operative initial approach as well as in the post-operative evaluation of the patients who had incontinence surgery. Bladder neck mobility and the position of the tape before and after sling surgery appear to be important factors for the assessment of these patients. The position of the bladder neck was calculated according to a standardised and reproducible method described by Schaer et al [1]. Using a co-ordinate system with the X-axis through the pubic symphysis and the Y-axis perpendicular to the X-axis at the posterior end of the pubic bone, the position of the bladder neck was measured at rest and during valsalva [2]. The vector between the two positions was calculated using the formula: √(x1-x2)2+(y1-y2)2 [3]. There is “no specific definition of normal” for bladder neck displacement; however, the definition of urethral hypermobility includes any mearuements between 15–25 mm. The aim of this study is to present the experience of our department from the use of pelvic floor ultrasound in the evaluation of patients who had sling surgery.

This is a prospective cohort study performed in a tertiary academic urogynecologic unit from January to December 2019. All patients who presented with pure SUI, or predominantly stress mixed urinary incontinence were invited to participate in the study. Inclusion criteria were: (a) age > 18-years-old, (b) Greek speakers, (c) women with at least moderate degree SUI/MUI. All patients had clinical examination, standardized cough test, and pad test. Symptoms were measured with the use of ICIQ-UI SF questionnaire, PFDI, PISQ-12, and EQ-5D, PGI-I. All patients had undergone a full urodynamics investigation (uroflowmetry, filling cystometry, pressure-flow studies, and urethral profilometry) before surgery. All patients had transobturator mid-urethral sling (PolyPropylene) with a standardised inside-out technique: tensioning of the tape was accomplished with a Hegar 8 dilator; indwelling catheter was kept overnight and removed the following morning; a trial of free voiding and sonographic measurement of the post-void residual (PVR) was performed 3-6 hours after catheter removal. Then, all patients had a 3 months post-operatively follow-up assessment with: (a) clinical exam and standardized stress test, (b) Patient Global Improvement-Symptoms (PGI-I) score, (c) Patient Global Improvement Impression (PGI-I) score, (d) trans-perineal ultrasound [urethral internal orifice mobility assessment, tape mobility assessment, and tape-urethral distance assessment). Statistical analysis was performed with JASP 0.11.1 (University of Amsterdam). Paired t-test was used to compare pre- and post-operative results. p<0.05 was considered statistically significant.

29 patients were recruited. Mean age was 61.3 (±5.9). All patients had moderate or severe USI pre-operatively. Pre-operative mean urethral mobility was 13.3 mm (±9.5 mm). Combined POP and incontinence surgery had the 75.8% (n=22/29), whereas tape surgery had 24.2% (n=7/29). Stress test after surgery was positive in 5 patients (17.2%), therefore the cure rate was estimated at 82.8% (24/29). Subjective cure rate was 79.3%: PGI-I score 1 / 2 had 79.3% of the patients, and PGI-S 1 / 2 had 75.9% of the patients. Mean urethral mobility was 10.6 mm (±5.8 mm), mean sling mobility was 11.2 mm (±5.9 mm), and mean sling distance from urethra was 4.9 mm (±0.7 mm). A post-operative positive stress test was more frequent in the elder women (60.0±4.4 years Vs 67.6±8.5mm, p=0.006). The measurements of urethral mobility were not significantly reduced post-operatively (p=0.35). Post-operative bladder neck mobility was statistically increased in the women with positive stress test (8.5±5.8mm Vs 15.5±0.9mm, p=0.04). The mobility of the sling as well as the position of the sling related to the pubic bone was not associated with post-operative faliures. A lower PGI-I score was associated with increased bladder neck mobility (8.5±5.8mm Vs 15.5±0.9mm, p=0.04).

It is well known that ultrasound offers a valuable assistance in the post-operative evaluation of the incontinence procedures. Dynamic ultrasound depicts the sonographic visible polypropylene tape and indicates the trajectory of the tape movement during a cough or a Valsalva maneouver, offering the opporunity of obtaining measurements of the bladdder neck, the tape, as well as the relative movement of the sling compared to the urethra. All this information is of paramount importance in order to explain the failure of the anti-incontinence mechanism of the sling in the cases with post-operative SUI. It appears that the urethral mobility remains increased in women who had a failured sling. The mobile urethra is described as a not enough tensioned sling that permits increased mobility post-operatively. Although there are many reasons for a sling failure, post-operative increased urethral mobility can be recognised sonographically allowing the clinician to offer further surgical treatment if necessary.

Sonographic increased post-operative urethral mobility is associated with poor surgical results and post-operative SUI.

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