ST. LOUIS — Placing a transobturator sling with a newer technique that starts inside the paraurethral space and progresses outward is both safer and more effective than the “outside-to-in” approach, according to Robert M. Rogers Jr., M.D., an expert in vaginal surgery.
Transobturator (TOT) slings are most commonly threaded through a skin incision in the pelvis and pulled through to the paravaginal space (the outside-to-in approach). This traditional approach poses the risk of bladder and urethra perforation and laceration of the anterior branch of the obturator artery, he explained at the 14th International Pelvic Reconstructive and Vaginal Surgery Conference.
In contrast, the “inside-to-out” approach begins laterally, away from the bladder and urethra, and twists helical-shaped passers away from the danger zones, said Dr. Rogers of Reading Hospital and Medical Center in West Reading, Pa.
“When you put the helical passers through and you drop the handle vertically into the perineum as you rotate, the engineering of the device keeps you out of trouble,” Dr. Rogers, a consultant and speaker for Gynecare, which makes the passers, said in an interview.
The outside-to-in approach involves a directional force toward the bladder and urethra. To protect these structures, the surgeon must dissect the adjacent paraurethral and paravaginal areas to place a finger to meet the instrument as it passes through the obturator internus muscle.
“That large paraurethral dissection can allow the tape to slip back up to the bladder neck or urethrovesical junction, and there's also a question in my mind about how much innervation to the bladder is disrupted by the large finger dissection,” he said in an interview.
The narrow paraurethral incision made in the inside-to-out approach ensures that the tape stays where it is placed—at the midurethra—without slipping back to the bladder neck.
Because of the decreased risk to the bladder and urethra with the inside-to-out approach, intraoperative cystoscopy is not necessary, whereas it must be a consideration when using the outside-to-in technique, he said.
The anterior branch of the obturator artery, which runs along the exterior edge of the obturator foramen, is the structure of most concern. “I've done studies in about 35 cadavers, and in about 60% of them we found an anterior branch of the obturator artery and vein, which traveled along the outer bony rim of the obturator foramen. Theoretically, on the outside-to-in approach, if you hit the edge of the foramen and then scrape down to get through the membrane, you could lacerate those vessels, and there have been external obturator groin hematomas reported with this,” he said.
The inside-to-out technique is unlikely to pose this problem, since from this angle the artery is shielded by the rim of the obturator foramen.