Rectus Muscle Sling Procedure for Severe Stress Urinary Incontinence

Type III stress urinary incontinence results from intrinsic dysfunction of the urethra and bladder neck incompetence. Effective repair must restore closure of the deficient urethra. Current surgical techniques include the use of fascial slings, vaginal island slings, artificial urinary sphincter, or periurethral injections. A variety of natural materials have been used for sling procedures, the most popular being fascia lata or rectus fascia. Synthetic materials are convenient but are more prone to problems of erosion or infection. The narrow dimensions of a traditional sling make it important that the surgeon position the sling accurately at the proximal urethra. A more distal location can produce outflow obstruction or problems with recurrent infection or voiding difficulty. The rectus muscle provides a broad platform of support for the bladder neck and urethra, and accurate placement seems to be less of a problem.

DIAGNOSIS

There is a clinical pattern of sacral neurogenic deficit that is characterized by flat feet and loss of intrinsic muscle function of the toes (inability to abduct the toes), and the lateral toes may be hypoplastic. On perineal examination, there is loss of two-point discrimination (4 cm) in the postanal (S5) or perianal (S4) dermatomes, and anal examination reveals loss of anal tone and anal grip that is weak and not sustained.

The severity of urinary leakage will give a clue to intrinsic urethral weakness. If the patient leaks with a flood in the supine position on the first or second cough, one should suspect type III stress urinary incontinence. Correction of bladder neck displacement with the examining finger will usually fail to correct the leakage. It is often difficult to assess urethral function in the presence of severe vaginal vault prolapse or procidentia because the prolapsing bladder base may obstruct the urethra. Surgical correction of the prolapse may reveal moderate or severe stress incontinence.

Objective urodynamic findings are essential to distinguish the patient who will require a sling procedure. Selection criteria for rectus muscle sling procedure were Valsalva leak-point pressures of less than 60 cm H2O and/or maximum urethral pressure (Brown and Wickam) of less than 20 cm H2O and/or a urethral length of less than 1.5 cm.

INDICATIONS FOR SURGERY

Traditional indications would reserve sling procedures for those who have failed a primary surgical repair. In contemporary practice, the sling is also used as a primary procedure for patients with severe stress urinary incontinence. Clinical features would include leakage with a flood that occurs instantly with the first cough in a supine position, in a patient with a comfortably full bladder, or leaks while standing without provocation.

Cystoscopic features include open bladder neck and short urethral length (<1.5 cm).

Patients who present with total vault prolapse with eversion of the vagina will also require a sling. It is my practice to identify and correct all of the pelvic support defects at the time of surgery.

ALTERNATIVE THERAPY

A variety of natural materials have been used for sling procedures, the most popular being fascia lata or rectus fascia. Synthetic materials are convenient but are more prone to problems of infection and erosion. The narrow dimensions of a traditional sling make it important that the surgeon position the sling accurately at the proximal urethra. A more distal location can produce outflow obstruction, problems with recurrent infection, or voiding difficulty. The artificial urinary sphincter or injection of periurethral bulking agents may be considered for the treatment of type III stress urinary incontinence.

SURGICAL TECHNIQUE

We have used a combined abdominal and vaginal approach. Venous compression pneumatic hose’s are applied and activated. The patient is placed in a modified dorsal lithotomy position with the lower limbs supported in the Sams modification of Allen stirrups. Independent grounding pads are placed for the abdominal and vaginal fields. Careful examination of the vagina and perineum confirms the presence or absence of fascial defects for repair. The most common defects are paravaginal, but anterior (pubocervical) or posterior (rectovaginal) fascial defects may also be present.

A midline incision is preferred, extending from the left of the umbilicus to the pubic crest. Alternatively, a transverse incision may be made, but this will require that the anterior rectus sheath be incised with a deep U incision and reflected upward to the level of the umbilicus. The rectus abdominis muscle is mobilized from the posterior aspect of the anterior rectus sheath, with care taken to preserve the epimysium, the outer fascial envelope that encloses the muscle bundles. This dissection progresses easily if the assistant elevates the fascial edge with Allis forceps and then Richardson retractors, and the surgeon works from the pubis toward the umbilicus. There are two small perforating vessels that pass anteriorly from the deep inferior epigastrics through the rectus abdominis muscle and the anterior rectus sheath to anastomose with the superficial epigastric vessels in the subcutaneous tissues. These perforators are coagulated and divided. At the lateral border of the rectus muscle, the segmental neurovascular bundles penetrate between the posterior and anterior layers of the rectus fascia; these bundles are coagulated, but the larger bundles may be ligated and divided.

Dissection to the lateral border of the muscle in the distal third allows the thin posterior fascia to be opened and the deep inferior epigastric pedicle to be palpated. If the pedicle has been ligated during an earlier procedure, the rectus muscle will be thin and not suitable, but the contralateral muscle can be used. If both pedicles have been ligated, the rectus muscle procedure would be abandoned, and a fascial sling substituted.

As dissection proceeds to the level of the umbilicus, a tendinous inscription will be noted where the anterior rectus fascia is adherent to the muscle. Above this level the direction of the fibers will change, and the muscle is mobilized for a further 2 cm cephalad to the tendinous inscription. The surgeon’s finger can now be passed from lateral to medial between the rectus muscle and the posterior rectus sheath. A large right-angle forceps is passed, and a heavy Vicryl ligature is carried around the muscle belly. As the ligature is tied, the muscle is divided, and the vascular pedicle is ligated. A second heavy ligature is tied, and the vessels are ligated and divided. Three holding sutures are placed through the tendon to facilitate the dissection and to be used later.

Dissection is continued until the muscle is free from all posterior attachments, and care is taken to clean all of the loose areolar tissue off the posterior rectus sheath to travel with the muscle; this will ensure that the vascular pedicle will be elevated with the muscle and preserved. The pubic insertion and the deep inferior epigastric vessels are not disturbed, but the muscle must be completely free from the overlying anterior rectus sheath and pyramidalis.

The muscle is held up by the holding sutures in the tendinous intersection and then folded along its longitudinal axis, by tying the lateral and medial holding sutures, to enclose and protect the vascular pedicle. The borders are approximated with two absorbable sutures in the middle third of the muscle.

The vaginal dissection is similar for other slings. The vaginal mucosa is elevated with injectable saline. We favor an inverted-U incision, but if access is narrow, a vertical incision is used. Dissection is carried out laterally to the pubic rami and forward under the bladder neck. The vaginal surgeon will elevate the endopelvic fascia, lateral and close to the pelvic side wall.

The abdominal surgeon will incise the endopelvic fascia and create an opening that will admit the passage of first one, and then two, fingers on the left side and then the right. The abdominal surgeon is usually able to guide the vaginal surgeon to avoid opening vaginal vessels, but on occasion the veins must be oversewn to control bleeding. Use of a spreading forceps (Knight Surgical Instrument Co.) allows the passage first of the holding sutures and then of the muscle belly through the ipsilateral defect to the vaginal surgeon. It is drawn downward to deliver the full length and then passed back into the pelvis through the other opening, while the spreading forceps within the pelvis hold open the defect in the endopelvic fascia. The tendinous inscription of the muscle is used to anchor the muscle sling to Cooper’s ligament with three or four nonabsorbable sutures. On occasion, the length of muscle will not reach up to Cooper’s ligament, and instead it will be secured to the internal obturator fascia.

The muscle belly fills the suburethral space and lies naturally without tension beneath the bladder neck and urethra. The suburethral muscle provides a broad support to the bladder neck and coaptation of the urethra. The vaginal wound is closed with interrupted absorbable sutures. If there are other support defects, the vaginal wound is closed first, before the colpopexy, and the paravaginal sutures from above (or the sacrocolpopexy fixation) are tied down.

Cystoscopy is done after intravenous injection of 5 ml of indigo carmine to confirm free efflux from the ureters. Cystoscopy is not used to adjust the sling but only to confirm the normal axis of the urethra and the closed appearance of the bladder neck. The bladder is drained with a urethral catheter. If there is a defect in the rectovaginal fascia or perineal body, this would be repaired after cystoscopy.

The abdominal wound is closed with interupted nylon sutures. Particular care is taken to close the fascia at the pubic crest.

The patient is mobilized on the first day. The catheter is drained to a bedside bag. It is removed when the patient has begun to pass flatus or had a bowel movement, usually on the third postoperative day. Voiding trials should begin at 3 hours, and after voiding efforts, straight catheterization should be done for residual volume. It is also necessary to drain the bladder one time in the course of the night in the first days. Most patients will require an interval of self-catheterization in the first 2 weeks, and some will use it for as long as 6 weeks. Preoperative teaching is done to encourage the transition through the interval of self-catheterization. When the catheterized volumes decrease to less than 60 ml, it can be tapered off. It is usually helpful to continue with the self-catheterization twice daily for a few days to be sure that emptying has been achieved.

OUTCOMES

Complication

Complications from this operation are few. Of 100 patients treated at our center since 1992, there was no mortality, and ten early complications included superficial wound infection (6), pelvic abscess (2), deep venous thrombosis (1), and fascial dehiscence (1). These complications all occurred early in the series, and some of these were related to the use of a suprapubic catheter. Special attention has been given to the surgical technique, including abandoning the use of suprapubic catheters, the introduction of antibiotic wound irrigation, and also the use of nonabsorbable sutures for the closure. There have been no wound problems in the last 26 cases.

There were 11 late complications including incisional hernia in nine. One patient had had multiple periurethral injections of Teflon, and the anterior vaginal wall was a solid indurated mass. After excision, the omentum was used to cover the muscle sling and repair the vaginal defect. This patient did well but developed prolapse of redundant omentum, which had to be trimmed after 6 months.

Results

One hundred patients have been treated for type III stress urinary incontinence with a rectus muscle sling since 1992. The medical record, patient interviews, and an independent questionnaire were used to evaluate the course and outcome of treatment. The interviews and questionnaires were done independently by a physician who was not a member of the surgical team. The mean age of the patients was 62 years, with a range of 24 to 83. The mean follow-up interval was 22 months, with a range of 3 to 47. Factors predisposing to incontinence included hysterectomy (79), lumbar stenosis (7), pelvic fractures (2), and traumatic paraplegia (1). Forty-nine patients had failed 86 previous surgical repairs, including MMK or bladder neck suspension (61), anterior repair (17), and periurethral collagen (8).

All patients had moderate or severe stress urinary incontinence, and all patients had preoperative videourodynamics. Selection criteria for rectus muscle sling procedure were Valsalva leak-point pressures of less than 60 cm H2O and/or maximum urethral pressure (Brown and Wickam) of less than 20 cm H2O and/or a urethral length of less than 1.5 cm.

Other anatomic defects were present in these patients, and other procedures were combined with the rectus muscle sling as needed. These procedures included sacrocolpopexy (34), paravaginal repair (31), and repair of urethrovaginal fistula (3).

The mean hospital stay was 6 days. On leaving hospital, 6% were already voiding to completion. Sixty-three were voiding but needed clean catheterization to empty, and 31% used a suprapubic catheter. After 2 months, 90% were voiding to completion, no patient had a suprapubic catheter, and only 10% used clean intermittent catheterization.

The pattern of voiding after a traditional sling may be slow or interrupted. It has been noticeable that voiding is quite normal for many of these patients after rectus muscle sling, and there are few complaints of irritative symptoms.

Of the 84 patients who responded to the independent questionnaire, 47% were dry and used no pads, and 33% were satisfied but were still using one or two pads a day. Twenty percent were not satisfied and still used 3 or more pads a day. Eighty-one percent of patients described themselves as improved or much improved after surgery.

This report represents a more complex group of patients than many series, because the majority had failed previous surgery, and no effort was made to exclude patients with risk factors of neuropathic disease, fistulas, or diabetes.

The rectus muscle flap is not difficult to develop, and the generous vascular pedicle is easy to protect during mobilization and transport of the flap. The muscle flap brings its own blood supply with it, providing excellent oxygenation for the healing tissues. This is an important consideration when dealing with complex problems of incontinence in patients who have had multiple surgical procedures or radiation therapy. This versatile flap may find many other applications in pelvic surgery.

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