Tips on retropubic vs. transobturator sling approaches.
Dr. Sokol's retropubic approach
I use newer retropubic midurethral slings with smaller trocars that have evolved from first-generation tension-free vaginal tape (TVT) slings. The slings I prefer are placed in a bottom-up fashion, with curved needles passed from a small vaginal incision up through the retropubic space to exit through two suprapubic incisions.
I find it helpful to place patients in a high lithotomy position with the legs supported in candy cane stirrups rather than Allen-type stirrups; sling placement is a short procedure with minimal to no risk of neuropathy.
To precisely identify the midurethral point, I use a 16-FR Foley catheter. When the catheter balloon is filled with 10 mm of fluid and gently pulled back, the urethrovesical junction can be identified. Then, by looking at the urethral meatus relative to the bladder neck, I can mark the midpoint between the two.
The suprapubic exit points are marked at two finger-widths lateral to the midline, just above the pubic symphysis. For precise identification of these points, the Foley catheter may be pulled up exactly midline (with the collection bag detached), and the two finger-widths measured on either side. I also aim for the ipsilateral shoulder, imagining a straight line from the urethral meatus to the ipsilateral shoulder on each side. Together, these measurements and visual cues serve as a good safety check.
With two Allis clamps, the vaginal wall on either side of the midline is grasped transversely at the level of the midurethral mark. The clamps will sit a couple of centimeters apart so that the midurethral point can be visualized. This helps to stabilize and elevate the midurethra.
To safely and efficiently develop a paraurethral passage, I perform a hydrodissection and hemostatic injection at the level of the midurethra using a control top 10-cc syringe with a 22-gauge needle. I find that dilute vasopressin saline solution affords better hemostasis than does a dilute lidocaine epinephrine solution, though I use dilute lidocaine if the sling is being done under local anesthesia.
The needle is inserted into a full thickness of skin, to a point shy of the urethra, and 10 cc is rapidly injected. The vaginal epithelium will appear blanched and will balloon out, like a white marble. The process basically lifts the vaginal skin away from the urethra itself, not only creating hemostasis but also providing a zone of safety to help avoid a urethral injury.
With a second syringe identical to the first, I inject 5 cc on each side of the midurethral point, aiming precisely at the underside of the pubic bone toward the ipsilateral shoulder. This creates a hydrodissected tunnel around each side of the midurethra. With a final syringe, I then inject 5 cc on each side suprapubically at my marked exit points.
With a #15 blade scalpel, I make two very small "poke" incisions transversely at the suprapubic sites. The suburethral incision is larger--just over a centimeter--and is made through a full thickness of skin under the area of hydrodissection, but not so deep as to injure the urethra. To finish development of the paraurethral passage, I pass standard Metzenbaum scissors through each hydrodissected tunnel until I feel the underside of the pubic bone, but no further.
For sling placement (after ensuring the bladder is completely empty), I lower the table such that my arm will be at a right angle to pass the sling while standing.
With my index finger underneath the pubic bone, the trocar tip, with the attached sling, is advanced with my thumb directly toward the ipsilateral shoulder just until it pops through the retropubic space. The depth of the trocar tip can be palpated with the index finger of the same hand, which is positioned just below the pelvic bone.
After the sling "pops" into the retropubic space, I remove my hand from the vagina and place it on the abdominal wall at the ipsilateral suprapubic poke site. In one smooth pass, I hug the pubic bone and advance the sling, again aiming directly and consistently at the shoulder. The trocar handle stays steady, never deviating in any direction. Cystoscopy is performed after the sling is placed on both sides to ensure bladder and urethral integrity.
For tensioning, I raise the table back up and, after reinserting the Foley catheter and a Sims retractor, I place my finger in the middle of the sling and pull the suprapubic ends of the sling up until my finger rests right under the urethra.
I then remove the vaginal clamps and use Metzenbaum scissors as a spacer between the sling and the urethra. With the scissors parallel to and right under the Foley catheter, at the same angle as the urethra, I tighten the sling and remove the plastic sheaths.
Dr. Sokol's transobturator (TOT) approach
I most often use an outside-in sling. I utilize the same patient positioning and identify the midurethral point in the same way as with the retropubic approach.
On the thigh, I identify the adductor longus tendon as well as a little soft spot or depression just beneath the tendon and lateral to the descending ischial pubic ramus. With my thumb on the soft spot, I can actually grasp the adductor longus tendon between my thumb and index finger. This spot, which is also approximately at the level of the clitoris, marks the entry point for sling placement.
I perform a similar hydrodissection under the urethra as I do in a retropubic procedure, though instead of injecting 5 cc's to the underside of the pubic symphysis on each side, I instead inject toward the obturator internus muscles. I then inject my final syringe of dilute vasopressin saline solution at the groin poke incision sites, directed toward the projected trocar path, as opposed to suprapubically.
After the full-thickness vaginal incision is made with the scalpel, the dissection is performed sharply with Metzenbaum scissors and is more like the dissection done for cystocele repair than for a retropubic sling. Rather than a poke, the midurethral incision is long enough--about 1.5 cm--for me to reach a finger behind the obturator internus muscle after having sharply dissected the suburethral tissue and fascia. The angle of the dissection is more lateral than for a retropubic sling, toward the underside of the descending ischiopubic ramus and obturator internus muscle.
To place the sling, I have one hand with an index finger in the midurethral tunnel under the obturator internus muscle to protect the urethra. The thumb of that same hand is used to push the helical trocar straight through the thigh poke incision with the handle starting at a 35-degree angle from vertical. The trocar tip is pushed until it can no longer go straight and is ready to be tightly turned around the descending ischiopubic ramus with the opposite hand. A distinct pop can be felt as the trocar tip advances through the obturator membrane and muscles. As the tip is advanced, the angle of the trocar is rotated from 35 degrees to vertical, almost perpendicular to the floor. At this point, the tip of the trocar should be guided out of the midurethral tunnel against the opposite index finger.
I utilize the same technique for tensioning a TOT sling as I do the retropubic sling.
Dr. Rardin's retropubic approach
I continue to use the original TVT sling with a 5-mm stainless steel, mechanically cut trocar and reusable handle. The newer slender needles may advance with less pressure, but I worry about them bending during passage.
I perform retropubic hydrodissection with a spinal needle using a top-down approach. With 40 cc of a very dilute solution of bupivacaine (Marcaine) with epinephrine on each side of the urethra, I create columns of hydrodissected space. Studies are inconsistent about the benefits of hydrodissection, but theoretically, it decreases the risk of bladder injury by pushing the bladder away from the pubic bone, creates effective hemostasis, and can provide analgesia that will be on board when the patient wakes up.
I bring the spinal needle down behind the pubic bone to the location of the urethral incision site, with my finger in the vagina, so I can feel the tip of the needle next to the urethra/ Foley catheter. For each side, I will inject 20 cc of the solution in this location, and the other 20 cc as I withdraw the needle upward.
For trocar passage, some surgeons are taught to advance the trocar until a pop is felt, then drop the handle and push upward. I view the maneuver as a consistent, smooth arch; for every degree that I advance the trocar, I drop the handle slightly in order to maintain contact with the back of the pubic bone throughout the pass. I continuously and simultaneously drop the handle and advance the trocar. Contact with the back of the pubic bone is maintained with a slight pulling on the back end of the trocar handle, while the forward hand pushes the trocar upward.
The target that I visualize for a retropubic pass is the patient's ipsilateral shoulder. If the patient is draped such that I cannot see the ipsilateral shoulder, I ask the anesthesia team to show me. I have also identified and marked the suprapubic points about 2-3 cm from each other on either side of the midline just about the pubic symphysis, but I consider the broader anatomic picture and purposeful visualization toward the ipsilateral shoulder to be an essential part of safe technique. In general, it is safer to be more medial than more lateral for the needle passage.
I continue to use a rigid catheter guide to deflect the bladder neck while passing the needles.
Cystoscopy is performed after both needles are placed but not yet pulled through. I fill the bladder until the ureteral orifices appear flattened, which confirms that the bladder is under enough distension to preclude any mucosal wrinkles.
At the midline of the sling, I advance the sheaths just enough so that I can grasp a 2- to 3-mm "knuckle" of the midportion of the sling with a Babcock clamp. I then pull the sling ends until the Babcock comes into gentle contact with the suburethral tissue. The sheaths encasing the sling are then removed, and the Babcock clamp is released to ensure a tension-free deployment.
The amount of tape that is pinched with the Babcock--the size of the "knuckle"--determines the tension. For a patient with a more profound problem, such as intrinsic sphincter deficiency or a lack of urethral hypermobility, I will grasp a smaller knuckle.
These steps ensure that the midportion of the tape will not tighten or become deformed under tension. Rather than use a spacer, I like to protect the midportion of the tape and prevent it from being stretched. I find that the approach is reproducible and results in a reliable amount of space between the urethra and sling when the procedure is completed.
Dr. Rardin's TOT approach
I employ an inside-out technique to the TOT procedure, and I utilize devices with segment of mesh that is shorter--only about 13 cm in length--than the original full-length mesh used in many TOT procedures. Once placed, the ends of the mesh penetrate the obturator membrane and obturator externus but not the adductor compartment of the thigh and groin.
In a study we presented last year at the annual meeting of the Society of Gynecologic Surgeons meeting, the shortened tape reduced postoperative groin pain, compared with full-length TOT tape without any reduction in subjective benefit. It appears that with shortened tape, we are anchoring the sling in tissues that provide critical support while avoiding the muscles that relate to the inner thigh/groin pain experienced by some patients. Effectiveness was not reduced, compared with full-length TOT slings.
These shortened slings are distinct from a single-incision sling, which is basically pushed into place. We still pass the needle all the way through a vaginal incision and out through the obturator foramen, and we pull the sling into place as we would any other TOT sling. The difference is that we're not leaving any mesh in the groin.
I prefer an inside-out approach for two reasons: I always feel that I have more control over where a needle enters than where it exits, and precision is important with suburethral slings. Secondly, the dissection tunnel created for an inside-out pass is much smaller than the tunnel that must be dissected for an outside-in approach. In theory, less dissection means less devascularization, less denervation, and less opportunity for erosion.
Hydrodissection for TOT slings is more minimal and involves less fluid than does hydrodissection for retropubic slings, mainly because we do not want to anesthetize the obturator nerve. I pass the spinal needle from the outside in. At the start, prior to making any incisions, I find it important to identify the arcus tendineus, a linear thickening of the superior fascia that is sometimes called the "white line." This is where the sulcus is affixed to the sidewall. I will be sure to penetrate the side's wall at or above the level of the arcus.
With the TOT approach, the likelihood of bladder injury is so low that I usually drive the trocars all the way through prior to cystoscopy, as opposed to leaving the needles in place as I do with the retropubic approach.
Tensioning is achieved in the same manner, by using the Babcock clamp to avoid distortion of the critical part of the mesh while creating the space needed given the patient's clinical scenario. It is worth remembering, at this point, that overall risks for retention appear to be lower for obturator slings, compared with retropubic slings.
I place most of my patients receiving retropubic slings in dorsal lithotomy position; but for obturator sling placement, I favor a few degrees into higher lithotomy because this pulls the obturator neurovascular bundle a little further out of the path of the needle.
Caption: SUI with Urethral Hypermobility
SUI with ISD, Nonmobile Urethra
The tension of a TVT sling may be adjusted using a Babcock clamp. In cases of intrinsic sphincter deficiency or absence of urethral mobility, a smaller "knuckle" of mesh is created in the midline to ensure a relatively tighter--but tension free--sling deployment.
BY ERIC R. SOKOL, M.D., AND CHARLES RARDIN, M.D.
Dr. Sokol reported that he owns stock in Pelvalon and is a clinical adviser to that company. He also is a national principal investigator for American Medical Systems and the recipient of research grants from Acell and several other companies. Dr. Rardin reported that he has no relevant financial disclosures. To view a video related to this article, go to Surgery U at aagl.org/obgyn-news.
Please note: Illustration(s) are not available due to copyright restrictions.
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|Author:||Sokol, Eric R.; Rardin, Charles|
|Publication:||OB GYN News|
|Date:||Feb 1, 2015|
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