Synthetic Midurethral Slings: TVT and TOT
The tips of the scissors are then used to create two tunnels to the level of the interior pubic ramus. The bladder is emptied and, using a catheter guide, the urethra is deflected in the direction opposite to the direction in which the needle is going to be passed.
The TVT needle is then directed toward the ipsilateral shoulder, and the tip of the needle is used to penetrate the urogenital diaphragm. No more than 0.5–0.75 inch of the needle should be passed in a lateral direction.
Once the urogenital diaphragm has been penetrated, the handle of the needle is dropped, and the tip of the needle is moved in a medial and superior direction. Be certain that the needle tip maintains contact with the back of the pubic bone. This is a very important landmark, and using it will help avoid migration of the needle into dangerous areas.
The next resistance that you will feel at the tip of the needle is the undersurface of the rectus muscle.
The needle is then used to penetrate the anterior abdominal fascia, and the tip comes up through the previously created stab wound. Cystoscopy is performed with the needle in place.
It is very important to overdistend the bladder and make sure that every millimeter of the bladder wall is visualized. Subtle penetrations can be easily missed if the bladder is not overdistended. Once it can be determined for certain that the needle has not penetrated the bladder, the needle is passed and the same procedure is repeated on the opposite side.
With the plastic sheath in place, you can achieve tensioning of the sling either through a cough stress test or suprapubic pressure. Some clinicians—believing that it's unnecessary to perform any sort of stress test—prefer just to place the sling loosely below the urethra, and that's fine.
If at all possible, I like to recreate SUI with suprapubic pressure or a cough, but at times this is not possible. With experience, you'll realize that the sling is placed very loosely most of the time. My end point in the majority of cases is being able to easily pass a right-angled clamp between the sling and the posterior urethra.
Preventing Complications
The most common complication of the TVT procedure is inadvertent penetration of the bladder. However, as long as this is diagnosed and the needle is withdrawn, the bladder emptied, and the needle repassed safely, penetration will rarely, if ever, cause any significant sequelae. In my opinion, these patients really do not even require any prolonged drainage, assuming that the penetration site is in a high, nondependent portion of the bladder.
Vascular injuries occur when the tip of the needle migrates away from the back of the pubic bone. Most commonly, this occurs when the needle is continued in a lateral direction and comes in close proximity with the obturator neurovascular bundle. If the needle is continued in a lateral direction, it may come in close proximity to the external iliac artery and vein.
Regarding bowel injuries, I strongly believe that this procedure should be avoided in patients who are at high risk for significant pelvic adhesions. This category includes patients who have had a ruptured appendix with peritonitis, patients who have had severe endometriosis and are known to have significant pelvic adhesions, and any patient you feel might be at high risk for having bowel adhered very low in the pelvis.
And again, we must not underestimate the importance of maintaining the contact of the needle on the back of the pubic bone. It is attention to specific anatomical landmarks such as this that make the operation both safe and successful.
A small percentage (less than 1%) of patients will have erosion of the tape. This outcome can be easily managed by either excising the eroded part of the tape or re-covering it with healthier tissue.
Rates of partial or complete retention postoperatively—a problem after any operation for SUI—have been very low and can be managed by either stretching or cutting the tape.
MICKEY M. KARRAM M.D.
Emily Brannan, Illustration
Vascular injuries may occur when the needle is continued in a lateral direction and comes in close proximity to the obturator neurovascular bundle. Courtesy Dr. Mickey M. Karram
Stress Urinary Incontinence
Until recently, gynecologists and urologists approached stress urinary incontinence differently. Gynecologists were champions of retropubic colpopexy procedures, while urologists performed sling procedures. Through Dr. Ulf Ulmsten's landmark work on stress urinary incontinence, culminating in the use of tension-free vaginal tape (TVT) in 1996, gynecologists and urologists throughout the world came to agree on a common procedure.
