Master Class
Midurethral slings – both retropubic and transobturator – have been extensively studied and have evolved to become standard therapies for the treatment of stress urinary incontinence. The two approaches utilize different routes for sling delivery, but in many other respects, they are similar. Improvements in technique are continually being developed. In this column, Dr. Sokol and Dr. Rardin share key parts of their technique and give their pearls of advice for midurethral sling surgery.
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.
Dr. Eric R. Sokol
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.