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Surgical Technique


New transobturator sling reduces risk of injury

By placing the tension-free sling between the 2 obturator foramens using a perineal approach, surgeons can eliminate complications that stem from passing needle carriers through the retropubic space. Here, 2 experts delineate this easily learned technique.

July 2003 · Vol. 15, No. 7

KEY POINTS

  • The route of the transobturator sling is strictly perineal, with a very short, blind passage through the crural region. This pathway ensures that the retropubic space is not entered and that the anatomic structures crossed by the needle passer and mesh are either muscle or fascia.
  • The transobturator approach eliminates the need for routine cystoscopy in most patients.
  • Short-term efficacy of the transobturator sling is similar to that of other suburethral tension-free slings.
  • In our experience, the transobturator approach reduces average operating time to 17 minutes.

Potential complications associated with passing needle carriers through the retropubic space are eliminated, and cystoscopy is not routinely required with the use of a transobturator sling.

Although it is effective and easy to perform,1-6 retropubic placement of suburethral tension-free vaginal tape (TVT) for the treatment of stress urinary incontinence has been associated with a number of bowel, vascular, nerve, and bladder injuries (TABLE).7-13

Such complications appear to be related to the unique upward vaginal passage of the metallic sling trocars through the retropubic space. Newer slings eliminate the upward approach, but still require routine cystoscopy to confirm an intact bladder and urethra.

A new tension-free suburethral sling addresses these shortcomings using an innovative transobturator route.14 In the new procedure, the surgeon uses needle passers to run the sling from one obturator foramen to the other. The perineal approach reproduces the natural suspension of the urethral fascia while preserving an intact retropubic space (FIGURE 1).

TABLE

Advantages of the transobturator sling

  • Offers short-term efficacy (1 year) similar to SPARC and tension-free vaginal tape systems
  • Reproduces natural suspension mechanism of pubocervical fascia and pubourethral ligaments, which may pose less risk for overcorrection and dysuria
  • Offers safe needle passage by avoiding the retropubic space
    • May eliminate vascular, bladder, and bowel injuries
    • Eliminates the need for cystoscopy in most patients
    • Avoids retropubic scarring
    • May prove useful in cases with scar tissue impedance
    • May prove useful in obese patients
    • May prove useful in treatment failures

  • Offers shortened procedure time
  • Increases surgeon comfort by minimizing blind perineal needle passage
  • Is easy to learn and teach

FIGURE 1 Suburethral slings: Retropubic and transobturator pathways



Traditional suburethral tension-free slings require the needle passers and sling to be placed through the retropubic space.

The newer transobturator sling uses a perineal approach. The needle passer and sling are passed from one obturator foramen to the other, preserving an intact retropubic space.

What does ‘tension-free’ mean?

Tension-free slings are used to treat stress urinary incontinence caused by urethral hypermobility and intrinsic sphincter deficiency. In this approach, a synthetic transvaginal suburethral sling is placed through the retropubic space without using suspension sutures. The sling is held in place by the friction between the mesh and the tissue canals created by the metallic needle passers. Scar tissue later fixes the mesh, preventing migration.

Short-term efficacy of the Monarc transobturator sling is similar to that of the SPARC and tension-free vaginal slings.

Because the sling is not anchored to the pubic bone, ligaments, or rectus fascia, it is considered “free of tension.” The result is a midcomplex urethral support that limits urethral descent, improves the stabilization mechanism generated by pubourethral ligaments and levator ani muscles, and reinforces support of the backboard vaginal hammock.

A tension-free sling designed to reduce injury

Since its introduction in the mid 1990s, retropubic placement of suburethral tension-free tape has continued to gain in popularity.15-22 The technique has several advantages: It is simple to perform under local, regional, or general anesthesia, and has proved to be a safe treatment for stress urinary incontinence, with minimal complications in experienced hands. Still, injuries have occurred7-13 —likely due to the blind passing of metal trocars from the vagina upward through the retropubic space.9,23

Downward placement introduced. In an effort to reduce these complications, tension-free sling systems that rely on suprapubic, downward needle-carrier placement through the retropubic space were developed, such as the SPARC Female Sling System (American Medical Systems, Minnetonka, Minn), introduced in 2001.24 The manufacturer of the traditional TVT (Gynecare, a division of Ethicon, Somerville, NJ) also recently introduced suprapubic needle passers. However, because these slings still require passage through the retropubic space, their use may lead to vascular, bowel, and bladder injury. Routine cystoscopy is therefore required.

The transobturator sling. In the Netherlands in 1998, Nickel et al25 reported a successful sling procedure using a polyester ribbon passed through the obturator foramen and around the urethra for treatment of refractory urethral sphincter incompetence in female dogs. In France in 2001, Delorme14 introduced the transobturator sling procedure in humans. Dargent et al26 then performed the operation in 71 patients using a technique inspired by Delorme, and found the shortterm results similar to those of the TVT.

The Monarc transobturator sling (American Medical Systems), introduced in Europe in January 2003, has been used successfully in more than 1,000 procedures ( FIGURE 2). This new system offers significant technical improvements over the original transobturator sling devices.

The Monarc transobturator sling, introduced in Europe in January 2003, has been used successfully in more than 1,000 procedures.

Specifically, the Monarc system simplifies rotation of the needle passer during insertion and extraction around the inferior aspect of the ischiopubic ramus. The 3-mm–diameter passers are specifically designed for right-side or left-side use. They are attached to fixed handles to create a natural wrist rotation. The sling connectors, meanwhile, facilitate rapid, effortless, and secure mesh placement and fixation.

FIGURE 2 Monarc transobturator sling system



The Monarc system consists of 2 stainless steel helical-shaped needle passers and a 1-cm by 35-cm polypropylene sling mesh with a protected sheath, attached connectors, and a reabsorbable tensioning suture.

Easy to learn and perform

Anesthesia may be local, regional, or general, and prophylactic antibiotics are routinely given. FIGURES 3 through 6 offer a detailed description of how to surgically place the Monarc transobturator sling for treatment of stress urinary incontinence. What follows is a brief overview:

After making a small vertical incision along the anterior vaginal mucosa, use a finger to locate the upper-inner corner of the obturator foramen—the safe zone for needle insertion. You will incise the skin at this point and introduce the needle tip perpendicularly. Rotate the needle, with the tip following the posterior surface of the pubic ramus, until the tip exits the vaginal incision. Repeat this process on the other side.

Attach the sling and its plastic sheath, then draw both out through the skin incisions by pulling back on the needle passers. Cut the mesh, adjust the tension, and close the incisions.

A Foley catheter and vaginal packing with metronidazole gel may be used at the surgeon’s discretion.

Route minimizes anatomical hazards. The pathway described ensures that there tropubic space is not entered and that muscle or fascia are the only anatomic structures crossed by the needle passer and mesh. No major vessels or nerves come in contact with the sling (FIGURES 7 and 8).

Our fluoroscopic observations of the transobturator sling in cadavers show that insertion of the needle passer through the obturator foramen with exit through the vaginal incision under the mid-urethra is precise and simple (FIGURE 9).

Our comparative studies in cadavers revealed that, despite the different shape and placement, lengths for the SPARC and Monarc transobturator slings in the same cadaver are almost equivalent—ranging from 12 to 14 cm, depending on the patient’s height and weight (FIGURE 10).

The transobturator sling involves fewer potential anatomical hazards than retropubic placement.

These considerations strongly suggest that the transobturator sling offers a simpler approach with fewer potential anatomic hazards than retropubic tension-free slings.

FIGURE 3 Vaginal incision



Inject a diluted vasoconstrictive solution into the anterior vaginal wall, and make a small vertical incision along the anterior vaginal mucosa 0.5 cm below the urethral meatus. Separate the vaginal epithelium from the underlying periurethral fascia using sharp and digital dissection, advancing bilaterally to the inferior pubic ramus. Insert a finger into the vaginal dissection and palpate the internal edge of the ischiopubic ramus and the upper-inner corner of the obturator foramen.

FIGURE 4 Needle entry: Transobturator sling procedure



The safe zone for needle insertion is the upper-inner corner of the obturator foramen (red line). The red dot indicates the recommended insertion site (upper inner corner).

The insertion area corresponds to the point where a horizontal line at the level of the clitoris crosses a vertical line at the level of the genitofemoral fold. Make a small skin incision at this point.

FIGURE 5 Needle passage: Transobturator sling procedure



Insert your left index finger into the vaginal incision on the patient’s left side. Holding the right-side Monarc needle, introduce the needle tip perpendicularly through the skin incision.

Place the thumb of your left hand onto the outside curve of the needle and gently push until its tip penetrates the obturator membrane and muscle. Use the needle’s tip to locate the pubic ramus, and rotate the needle so that the tip follows the posterior surface of this structure.

Continue this rotation, using your left index finger to guide the needle tip to exit the vaginal incision.

Repeat steps A and B on the contralateral side.

With the needle-passer tips extending out of the vaginal incision, attach the sling and its plastic sheath using the connectors. Make sure the mesh lies flat and is not twisted before attaching the connector to the second needle.

FIGURE 7 Route of transobturator sling minimizes anatomical hazards



The needle travels around the ischiopubic ramus. Transobturator needle passage begins with penetration of the skin and subcutaneous tissue. After traversing the superficial perineal fascia, the needle crosses the adductor muscles of the thigh near their pubic bone origin and below the insertion point of the adductor longus tendon (arrow). It then penetrates the obturator membrane, obturator internus muscle, and periurethral endopelvic fascia. After passing the level of the white line—either over or under the puborectalis section of the levator—the needle exits through the vaginal incision.

FIGURE 8 The obturator foramen



The tough obturator membrane covers the foramen. The obturator canal is 2 to 3 cm long and is located at the anterolateral upper margin of the membrane. The distance between the safe zone for needle insertion and the obturator canal is approximately 3.5 to 4 cm. At the safe entry zone (green area), the anterior branch of the obturator artery is reduced to a capillary diameter and no significant arteries, veins, or nerve pedicles are present.

FIGURE 10 Routes of transobturator and retropubic slings



Graphic depiction of both the transobturator sling and the retropubic tension-free sling in place.

Fluoroscopic image of both slings in a cadaver. The transobturator sling runs horizontally while the retropubic tension-free sling forms a tighter “U.”

Clinical experience yields positive results

Early European series and our initial experience suggest that the short-term efficacy of the Monarc transobturator sling is similar to that of the SPARC and TVT slings. Average operating time is 17 minutes. The technique involves a short learning curve (approximately 4 cases).

Cystoscopy is not routinely required; we perform it only in women with significant prolapse or suspected urethral injury, and have encountered no intraoperative or post-operative complications.

No major vessels or nerves come in contact with the transobturator tension-free sling.

No patients have complained of postoperative pain in the area of the adductor muscles of the thigh, and no sling erosions have occurred. We also have found this approach useful in obese patients and women with retropubic scarring, in whom retropubic needle passage can be a challenge.

Continued...
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