In 1996, Falconer et al. described the tension-free vaginal tape (TVT) for correcting stress urinary incontinence (102). In this technique, polypropylene mesh is placed under the midurethra with minimal tension (Fig. 26.12 A, B). To perform this operation, a small midurethral incision is made in the vaginal epithelium mucosa. A 40-by 1-cm mesh tape covered by a plastic sheath and attached to two 5-mm curved trocars is passed lateral to the urethra and through the endopelvic fascia into the retropubic space. The trocar is passed along the back of the pubic bone, through the rectus fascia, and into two small suprapubic skin incisions. The tension on the tape is adjusted, the sheath is removed, and the remaining tape is cut off at the level of the skin. This technique has the advantage of being performed quickly using limited anesthesia (fewer than 30 minutes in experienced hands). The procedure requires the use of a catheter guide to deviate the urethra and cystoscopy to ensure that bladder or urethral perforations are recognized immediately because the trocar is passed blindly.
Numerous modifications of the TVT were proposed and marketed. Such devices generally circumvent the stringent regulatory control provided by the FDA by gaining approval through a Premarket Notification 510(k). This mechanism is a submission to the FDA demonstrating that a new device is substantially equivalent either to a legally marketed or “predicate” device introduced before 1976 in the United States or to one approved by the FDA through the 510(k)
Figure 26.12 Midurethral synthetic slings involve the use of large pore, monofilament polypropylene mesh placed after minimal dissection at the midurethra followed by placement of a trocar through the retropubic route. Some surgeons prefer placing the trocar by a suprapubic route beginning with a small abdominal incision. A: The trocar is guided into the previously performed midurethral incision with care to place the trocar against the pubic bone to avoid entry into the peritoneal cavity. The trocar handle has been removed in this view after perforation through the abdominal incision. B: The synthetic sling should rest in the midurethra location and is brought through two stab incisions above the pubic symphysis. (Redrawn from original by Jasmine Tan.) process itself. Substantial equivalence means the new device has the same intended use as the predicate device and has the same technological characteristics or different technological characteristics, but it is as safe and effective as the predicate device. Surgeons should be aware that most new devices for urinary incontinence are not tested in clinical trials before they are marketed.