Current Treatment Concepts for Stress Urinary Incontinence

Preoperative investigation

Before deciding for surgery, all conservative treatment options should be exhausted, the tissue should be well-estrogenized and built-up and thus, suitable for the operative intervention. In addition to clinical examination and urodynamics, pelvic floor sonography is very important for the precise planning of the incontinence surgery. Pelvic floor sonography enables the assessment of the entire small pelvis including the anterior, apical and posterior compartments [19].

Sonographic findings allow very precise recommendations for surgical indications and the acquisition of operationally important details to plan the intervention. According to radiological and morphological investigations by Ulmsten and Petros, the suburethral sling has to be positioned precisely within the middle third of the urethra, the key area for achieving continence, between the point of maximal urethral closure pressure at rest and the urethral knee which anatomically corresponds to the attachment site of the ligamenta pubourethralia [11, 20, 21]. Our studies [22, 23, 24, 25, 26] published in recent years showed that a detailed sonographic diagnosis of the lower urinary tract with special consideration of the physiologically variable urethral length allowed an exact positioning of the sling and thus, optimizes surgical outcome. Assessments of urethral length and mobility (Fig. 2) and the height of the paraurethral sulci (Fig. 3) are crucial for selecting the best suited pathway (retropubic or transobturator approach) and the optimal placement of the suburethral sling.

Types of tapes

Incontinence surgeries with tension-free tapes are performed under local anesthesia with analgosedation. Thereby, a macroporous monofilament band of polypropylene is suburethrally inserted. Fibroblasts eventually migrate into the band resulting in a “natural reconstruction” of the tissue. This leads to a new support of the urethra at stress condition.

The suburethral slings currently available on the market require different insertion and fixation techniques. They can be divided into three groups.

The placement of the classic TVT is retropubic (Fig. 1-B), while the placement of the TOT is by the transobturator approach (Fig. 1-F). Both options are equally successful regarding cure rates of stress incontinence (80–95 %) [17, 27]. Regarding complications, bladder injuries and emptying disorders are more frequent with the retropubic method, while pain (hip/groin/thigh/pubic bone), dyspareunia and band erosions (Fig. 3) are more frequent with the transobturator method. In case of an elevated proximal urethra and a high, well preserved sulcus vaginalis (nullipara/status after preoperations), the classic retropubic tape has a better outcome than the transobturator tape [17]. In case of a low position of the urethra and a flat sulcus vaginalis (middle-sized cysto urethrocele/rotatory descent; no preoperations) also a transobturator placement (TOT) can be considered. Furthermore, it has to be taken into account that retropubic tapes tend to pull towards the proximal, and transoburator tapes towards the distal direction [26, 28].

The third innovation involves slings with short arms. With this alternative, the operation procedure should be less invasive and the risk of injury and pain should be reduced. But these so-called “mini slings” are no valuable alternative to the classic TVT. First, long-term records are missing and second, initial data suggest a suboptimal stabilization of the tape and lower cure rates [17]. In addition, the two most commonly used mini slings are no longer available on the market.

Intraoperative assessments

The incision site should intraoperatively be determined based on the sonographically measured urethral length (Fig. 2-A). Ideally, the optimal tape position is at the transition of the middle to the distal third of the urethra (Fig. 4-A). This can be achieved by starting the incision at a distance from the external urethral orifice corresponding to one-third of the sonographically determined urethral length, i. e., an urethral length of 45 mm requires an incision at 15 mm distance, and a short urethral length of 18 mm requires an incision starting at 6 mm from the external urethral orifice.

Furthermore, the evaluation of the urethral mobility is important since the tension-free positioning of the tape also depends on this parameter (Fig. 2-B). For a rotatory descensus urethrae and a normal and hypermobile urethra, the straightforward intraoperative determination of the tape-urethra distance with the Cooper scissors is sufficient to achieve a tension-free position of the tape. However, for a vertical descensus and a hypo- and immobile urethra, this procedure can lead to a too large tape-urethra distance and to only a minimal improvement of the incontinence, or even to therapeutic failure. In these cases, the intra-operative cough test is very important to adjust the tape with the low mobility of the urethra.

A correct operative positioning of the tape is more successful under physiological anatomical conditions (normal, non-relaxed tone of the pelvic floor). This requires an operative procedure in local anesthesia under analgosedation, as initially described [12]. Prerequisites are: An exact operative technique (precise setting of local anesthesia), a careful operation and a well-coordinated timing of operative steps and anesthesia (sedation/setting of local anesthesia/incision and pull through of the tape/cystoscopy/ cough test).

The distance between tape and urethra has a large impact on success and complication rates of the operation (Fig. 4-B). A large tape-urethra distance of >5 mm is associated with a lower cure rate. Patients with a too closely positioned tape, i.e. at <3 mm from the urethra, are significantly more often confronted with obstruction complications like voiding dysfunction and/or de novo urge incontinence. The tape should be located at the transition site of the middle to the distal third of the urethra (Fig. 4-A), with an ideal tape-urethra distance between 3 and 5 mm (Fig. 4-B), and without urethral kinking.

Recovery time after this operation is short and surgical scars are minimal. Long-term data show an objective cure rate of 83 %, and a high subjective satisfaction rate of up to 95 % [23].

Postoperative evaluation and complications after tape insertion

Frequency and severity of complications after incontinence surgeries [17] depend, inter alia, on the operative technique (type of tape, following a standardized procedure) and on the experience of the surgeon. Early complications are bladder perforations, bleedings in the puncture channel, urinary retention and persistent stress urinary incontinence. Late complications, which may develop after years and become increasingly disturbing, are micturition disorders, urge and pain symptoms, residual urine formation, recurrent urinary tract infections, irritable bladder problems, ulcer formation in the area of the tape, dyspareunia and also recurrent stress urinary incontinence.

It is important to identify an incorrectly positioned (dystopic) tape and to adjust it as soon as possible [25]. The early postoperative urogynecologic pelvic floor sonography proves to be essential to detect the so-called “failures” of the method or to find the causes for postoperative complications. Pelvic floor sonography allows a good visualization of the tape position relative to the urethra (Fig. 4). Furthermore, tape-related, obstructive micturition disorders with residual urine can easily be detected at an early stage. Postoperative seromas and hematomas can also be identified. Therefore, in presence of increased postoperative residual urine values or symptoms of urge/pain [29], an ultrasound analysis in sagittal (Fig. 4) and transversal planes should be performed in the first postoperative days.

After TVT insertion, voiding dysfunction can be observed for 5 % of the patients. Very often, this complication is caused by a dystopic tape position (tape too tight, too close to the urethra or at the level of the bladder neck). But voiding dysfunction can also be caused by tape distortion, by only a punctual action of the tape on the urethra, or by kinking of the urethra.

Tape mobilization and tape incision

Tape mobilization is a simple and successful method to cure urethral obstruction with disturbed voiding due to a too tightly positioned or C-shaped tape, without compromising the outcome of the original stress urinary incontinence surgery [25]. This method is performed by reopening the suburethral incision within the first days after tape insertion (Fig. 5) [25, 30]. In cases of an asymmetrically placed tape, pelvic floor sonography also allows to localize the ideal side for tape loosening. Tape mobilization usually is not necessary for tape-urethra distances >3 mm, since in most cases, voiding dysfunctions resolved simultaneously with reduction of edema, pain and muscle contractions and with resorption of the hematomas. However, smaller tape-urethra distances (<3 mm) require a tape mobilization. Also here, the experience of the surgeon plays an important role. When the tape is only stretched, but not actually mobilized, it simply returns back into its original position. Conversely, overly aggressive tape loosening increases the risk for recurrent stress urinary incontinence. Price et al. [31, 32] identified the benefits of tape mobilization immediately after TVT placement as a resolution of voiding problems and to avoid long-term catheterization.

Already a few days after tape insertion, fibroblasts grow into the polypropylene band. Then, urinary retention can only be cured by sling incision. However, this procedure results in a high recurrence rate of stress urinary incontinence of up to 50 % [32]. In cases of voiding dysfunction, or symptoms of urge and urethral pain, the sling is dissected suburethrally, a slightly opened clamp is placed below it and the sling is completely severed with scissors in between the arms of the clamp. In presence of mesh exposure, the visible part of the sling needs to be resected underneath the healthy skin, sufficiently distant from the exposure.

In contrast to tape incision, early tape mobilization represents a much simpler and more successful method to treat voiding dysfunction due to a too tightly positioned tape. Furthermore, tape mobilization can resolve this frequent complication without requiring a second hospitalization and without generating much additional costs. Unfortunately, the resolution of simple complications often starts too late [33] and is nonprofessional (extensive conservative therapy instead of surgery, or only incomplete tape incision). Frequently, this results in tedious, unnecessary suffering. If stress urinary incontinence persisted after the first tape insertion, a second tape can be placed, provided that the urodynamic assessment shows a functional-operative indication.