It is well known that the position of incontinence meshes is important for both the outcomes and the complications regarding this kind of surgery (1). We wanted to assure if, in our institution, the position of the meshes measured from the bladder neck and the longitudinal smooth muscle urethral complex was directly related to the results. We were specially focused on the recurrence or persistence of the stress incontinence, and the onset of de novo urinary urgency, voiding disfunction, dyspareunia, pain or recurrent urinary tract infections (UTI). The aim of the study is to assess if we can improve our results in this surgery.

For this retrospective study, we focused on just one type of mesh, transobturator tape Contasure KIM (Neomedic), performed at our hospital between 2012 and 2018, studying a total of 614 patients. We followed the patients for a minimum of 5 years, and we performed a 2D introital ultrasound (US) using a Xario 100G with transvaginal probe, always performed by the same three gynecologists with specialization on pelvic floor disorders at our urogynecology unit. We measured the distance of the mesh to the bladder neck and the distance to the urethral complex.

Based on other published papers (1), we decided to fix a cut-off point of 15 mm from the superior part of the mesh and the bladder neck position (setting it as the proximal urethra, thinking of a feminine urethra of approximately 40 mm -35 to 45mm-), and a distance from the mesh to the urethral complex of 2,5 mm, to study the hypothesis that, if the mesh was too close to the complex or located on the proximal third of the urethra, we would find more complications in our results.

Of 614 patients, with a BMI of 27,82 (overweight), 40% had mixed urinary incontinence and 60% pure stress urinary incontinence (SUI). Just one of them had previous surgery for stress incontinence (retropubic sling). There was persistence of stress incontinence in 17 patients (2,77%), and recurrence among the 5 years or more of follow up in 29 (4,72%) of them, with a medium time of recurrence of 2 years and 8 months. 21 (3,42%) presented de novo voiding disfunction. 100 (16,7%) related de novo urinary urgency. 30 (4,89%) started feeling pain or dyspareunia after the surgery. In 41 (6,68%) recurrent UTI was observed. There were no bladder erosions, and just 2 (0,33%) urethral erosions (4 years and 8 years after the surgery). In 4 patients (0,65%) the sling was found to be in intimate contact with the urethral wall in the ultrasound, but urethral erosion was not confirmed by cystoscopy, nor did the patient have any pain or recurrent UTI; one of them had de novo urgency, and another one had de novo voiding disfunction.

Regarding US measurements, we studied them individually about each specific possible complication:

-Voiding disfunction: of 21 cases, we just had US measurement on 6 (28,5%). 4 (66,6%) were at a distance of 2,5 mm or less to the urethra, and 4 of 5 (80%) at less than 15 mm from the bladder neck (there was 1 measurement missed). Medium distance to the complex was 2,45 mm, and medium distance to the bladder neck was 14,5 mm.

-De novo urgency: of 100 cases, we had US measurement on 51 (51%). One complex measurement was missed; of the other 50, 9 (18%) were of 2,5 mm or less. 12 bladder neck measurements were missed, and of the other 39, 24 (61,5%) were of 15 mm or less. Medium distance to the complex was 3,59 mm, and medium distance to the bladder neck was 16,27 mm.

-Pain/dispareunia: of 30 cases, just 13 (43,33%) US measurements were registered. 3 meshes (23,7%) were at 2,5 mm or less from the urethral complex, and 7 (53,84%) were at 15 mm or less from the bladder neck. Medium distance to the complex was 3,48 mm, and medium distance to the bladder neck was 16,6 mm.

-Recurrent UTI: of 41 cases, we only had US data recorded on 18 (43,9%). 6 (33,3%) were at 2,5 mm or less of the complex, and 10 (55,5%) were at a distance of 15 mm or closer to the bladder neck. Medium distance to the complex was 3,09 mm, and medium distance to the bladder neck was 14,4 mm.

-Persistent SUI: of 17 patients, we only have registered 4 US measurements. None of them was closer than 3,4 mm from the urethral complex. The medium distance was 5,2 mm. There were no recorded measurements of distance to the bladder neck.

-Recurrent SUI: of 29 women, we had US measurements on 14 (48,47%). 2 (14,28%) were at 2,5 mm or closer to the urethra. We missed 1 bladder neck distance measurement, and, from the other 13 cases, 7 (53,84%) were at 15 mm or less. Medium distance to the complex was 3,92 mm, and medium distance to the bladder neck was 18,04 mm.

Our results are not as complete as we would like, because we started measuring ultrasound distances just a few years ago. Therefore, we have a lot of slings not studied conveniently, so we could not include them in our study.

Of all the results we show here, we would like to emphasize the following:
-Regarding de novo urgency, we have found it seems to be more important the distance to the bladder neck than the distance to the urethral complex. This can serve us to improve our results, trying to stay as far as reasonably possible of the bladder neck, and to specially check at each patient where exactly the middle third of her urethra is.
-Regarding voiding disfunction, it seems both of the measurements are as important, although we can´t extract so much information of our study because there were just a few cases reported.
-Acording to our results, persistent SUI was related to larger distances to the urethral complex, but we need to complete this data with more cases.
-We did not find any relation between pelvic pain nor dyspareunia and ultrasound measurements.

There are lots of studies about importance of the placement of the slings (2) and, with our results, we think we have found and interesting field where we can improve the complication rate of our patients, as other studies are emerging about the use of US at the surgery to exactly assess where we are placing it (3). Further studies will be performed at our hospital based on this one we are presenting.

Kociszewski J, Fabian G, Grothey S, Kuszka A, Zwierzchowska A, Majkusiak W, Barcz E. Are complications of stress urinary incontinence surgery procedures associated with the position of the sling? Int J Urol. 2017 Feb;24(2):145-150. doi: 10.1111/iju.13262. Epub 2016 Dec 1. PMID: 27907976.
Chantarasorn V, Shek KL, Dietz HP. Sonographic appearance of transobturator slings: implications for function and dysfunction. Int Urogynecol J. 2011 Apr;22(4):493-8. doi: 10.1007/s00192-010-1306-y. Epub 2010 Oct 22. PMID: 20967418.
González-Díaz E, Fernández Fernández C, Martin Corral AV, Gutierrez SH. Use of intraoperative ultrasound to improve tension-free vaginal tape-obturator placement: A pilot study. Int J Gynaecol Obstet. 2023 Jun;161(3):833-838. doi: 10.1002/ijgo.14671. Epub 2023 Feb 15. PMID: 36637252.