Sling augments membranous urethra without obstruction

Dr. Rehder, senior reconstructive urologist and deputy chief neurourology, and colleagues at the Medical University of Innsbruck, Austria, looked at the urinary function of 103 men treated with the sling using postoperative dynamic magnetic resonance imaging, intraoperative transrectal ultrasound (TRUS), intraoperative retrograde urethrographies, and intraoperative flexible and rigid cystoscopies.

Pre and postoperative MRIs demonstrated relocation of the proximal bulb by the sling, and dissections from 19 cadavers demonstrated that, even with the maximum tension, the sling does not obstruct the urethral lumen.

MRIs showed clearly that the membranous urethra lengthened when the sling was in its final position.

"It's a one-time procedure, minimally invasive, and after removal of the transurethral catheter, the patient should be immediately continent," Dr. Rehder said. "There are a few fine points of technique that you have to follow, but if you do the steps correctly, then it gives an 80% dry rate."

This approach is very different from that of compressive slings, he explained. For example, after radical prostatectomy, the sphincter mechanism is actually prolapsed. Rather than exerting direct compression on the urethral lumen as compressive slings do, this sling actually relocates structures. This approach, Dr. Rehder said, "is based on a theory that, separate from intrinsic sphincter deficiency, there is also an element of hypermobility in some patients with residual sphincter function, and you can correct this hypermobility by the transobturator retrourethral or retroluminal sling."

Patients with severe incontinence resulting from sphincter damage are unable to use the slings. Other contraindications are an immobile urethra from previous urethroplasty, radiotherapy, previous bulking agents, or stem cells.

"This procedure either works or it doesn't," Dr. Rehder said.

When it doesn't, he said, it's easy to proceed with placing an artificial urinary sphincter because the sling is very proximal, directly underneath the membranous urethra. But sometimes putting in a second sling is an option when the initial sling has slipped or loosened because patients with constipation bear down during evacuation or when patients climb high steps or spread their legs.

Technical advice

Dr. Rehder offered his colleagues pearls on sling placement.

A sling placed too distal can obstruct the lumen and might erode. If the sling is placed too proximal on the corpus spongiosum, the membranous urethra might be distorted, rather than supported and coapted, and it could exacerbate incontinence. When the sling is placed correctly, the long-term danger of erosion is minimal because the sling is supported in a straight line underneath the lumen, Dr. Rehder said.

He also advised his colleagues to be sure the bulb is completely mobilized. The introducer needles should curve into the obturator fossa as high as possible under the insertion of the adductor longus tendon.

"The most important point of the whole procedure," Dr. Rehder said, "is that the needle should come out into the greater perineal wound in the uppermost corner of the triangle between the bulb and inferior pubic ramus."

Dr. Rehder is co-inventor of the AdVance sling with Christian Gozzi, MD. Both urologists are consultants for American Medical Systems.