TOT Sling >>
Transobturator Sling for Stress Incontinence (Subfascial Hammock) Continued
Transobturator Anatomy
TOT Sling Figure: 1
The obturator foramen is covered by a thick membrane called the obturator membrane. The external and internal obturator muscles cover this membrane. It is a very safe space anatomically, ie there are no major vascular or nerve structures near the ischiopubic ramus. This is the area that the needle is passed for the tot sling placement. As can be visualized by the drawing, the obturator canal is very lateral and superior to the ischiopubic ramus, this is the area that the obturator nerve and vessels transverse.
TOT Sling Figure: 2
The needle to place the TOT sling is passed through the groin incision, the obturator membrane and around the descending ischiopubic ramus (the area marked in green in the above diagram). A small incision is made vaginally as well and the needle is guided throughout its course with a finger placed in the vaginal incision, thus protecting the urethra and making it safer than just a blind needle passage. The mesh tape (the same mesh tape that is used for SPARC, TVT sling etc) is then attached to the needle and brought back through the incision (see surgical technique below). The obturator vessels and nerve coming through the canal (in pink above) are far away from the surgical field, thus making injury very unlikely.
The TOT needle used to place the sling has minimal blind passage making it very safe, additionally NEITHER the needle nor the tot sling has to be passed through the abdominal wall like traditional slingsTOT Needle Passage
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TOT Sling Figure: 3 |
TOT Sling Figure: 4 |
Figure 3 demonstrates the positioning of the needle passage in the Monarc transobturator sling (tot sling), made by American Medical Systems. This is just one of the many types of TOT sling currently on the market.
Figure 4 demonstrates the passage of the needle viewed from the inside of the pelvis. Again a very safe area to pass the needle through to place the tot sling. This area is below the fascia of the bladder and therefore the retropubic space is never entered and the bladder remains very protected with this approach.
TOT Mimics Normal Anatomy
The transobturator sling (tot sling) forms a subfascial hammock of support under the urethra. This mimics the normal position of the pubourethral ligament. This is the ligament that typically provides the backboard of support to help prevent urinary leakage with stress events such as coughing, laughing, sneezing, exercising, etc. When this ligament is damaged or stretched out secondary to childbirth, aging, chronic straining, etc, stress urinary leakage may ensue. The position of the transobturator sling (tot sling) reproduces the natural position of this ligament and in a sense replaces the damaged ligament with a permanent mesh tape that provides the support needed to prevent leakage (figure C below). As can be seen in figure D below, the angle of the TOT sling is much less acute than the traditional pubovaginal sling procedures such as the TVT sling or SPARC, therefore not only is this more anatomic and natural, it also makes sense that there is less problems with urinary dysfunction such as urinary obstruction (not being able to void). Figure E is an MRI that demonstrates the position of the TOT sling is almost identical to the natural position of the pubourethral ligament.
TOT Sling Figure: 5
Figure 5: Position of TOT sling duplicates position of pubourethral ligaments.
TOT Sling Figure: 6
Figure 6: TOT sling angle is much less acute than traditional sling, it is felt that this angle is more natural and may reduce post-op voiding dysfunction.
TOT Sling Figure: 7
Figure 7: The TOT sling (red) is shown in this MRI to mimic the natural position of the pubourethral ligament (green) which is the ligament known to be responsible for maintaining continence.
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