Preoperative Preparation and Planning
Midurethral synthetic slings are the most common antiincontinence procedure performed for stress urinary incontinence, owing to their minimally invasive placement, quick postoperative recovery, relatively high success rates, and overall low complication rates. Originally described as a retropubic procedure, alternative approaches such as transobturator, prepubic, and single incision vaginal were developed to try to reduce associated complications. These differ by the site of introduction and route of needle passage.
Transobturator slings can be inserted using an “outside-to-inside” or “inside-to-outside” technique, with both approaches having similar outcomes. Level 1 evidence suggests that the transobturator technique achieves equivalent continence rates to the retropubic, with less risk of bowel/bladder perforation and postoperative voiding dysfunction. However, transobturator slings can lead to the unique complication of thigh/groin pain and numbness in 10%–15% of patients, which can be debilitating. In addition, the retropubic approach may lead to higher dry rates in patients with more severe stress incontinence, and may be more durable long-term (>24 months). Nevertheless, for the index stress incontinent female patient, the transobturator midurethral sling is a safe and effective alternative to the retropubic sling, and for many practitioners, it is their primary sling choice. Furthermore, the transobturator route is favored in patients where the avoidance of the retropubic space is preferred, such as in cases of obesity, lower ventral hernia, or history of extensive retropubic or bladder surgery.
Patient Positioning and Surgical Incision
Setup : Administer preoperative antibiotics (first- or second-generation cephalosporin) within 1 hour of skin incision. Local, regional, or general anesthesia may be employed. After induction of anesthesia, place the patient in the lithotomy position using stirrups that can easily be repositioned during the case. With the inside-out technique, flexing the hip to 100–110 degrees may reduce aberrant needle/trocar placement. Clip genital hair if it obstructs vision. Perform a full vaginal, lower abdominal, and inner thigh antiseptic skin prep and drape the patient to expose the vagina and the obturator region. Place a weighted vaginal speculum, and retract the labia minora with sutures to maximize visualization of the anterior vaginal wall. Mild Trendelenburg position can also aid visualization. Place a 16F catheter to evacuate the bladder and leave open to drain.
Vaginal dissection ( Fig. 100.1 ): Starting 1 cm below the urethral meatus, measure a 2-cm incision vertically. If desired, inject normal saline, or vasoactive local anesthetic (e.g., 1% lidocaine or 0.25% marcaine with epinephrine) for hydrodissection. Grasp the vaginal wall just above the incision with an Allis clamp to gain upward traction and aid visualization. Carefully incise the vaginal mucosa with a no. 15 blade, taking care not to go too deeply to injure the urethra.
Raise the length of each edge of vaginal mucosa from the underlying periurethral fascia for about 4–5 mm laterally using Metzenbaum scissors and a single-toothed forceps, taking care not to tear the mucosa. This will make it easier to grasp the edge of the incision, which is now done with an Allis clamp. Starting on one side, dissect the flap of vaginal mucosa laterally, toward the ipsilateral inferior pubic ramus with Metzenbaum scissors. The tip of the index finger holding the Allis clamp is used to guide the thickness of the developing vaginal flap, avoiding accidental perforation of the vaginal mucosa (which can predispose to vaginal mesh erosion). If the dissection is too deep, the urethra can be injured or venous bleeding can be encountered. Continue to dissect laterally until the inferior ramus of the pubis is clearly palpable. Do not pierce the endopelvic fascia. Repeat this dissection on the contralateral side.
If the urethra is injured during dissection, the injury is repaired using 4-0 synthetic absorbable sutures (SASs) in a water-tight, tension-free manner over the 16F catheter and the procedure typically postponed for 6–12 weeks to allow the urethra to heal. This prevents subsequent urethral mesh erosion or urethrovaginal fistula. If the vaginal mucosa is injured, it can be repaired using 3-0 SAS and the procedure may be continued.
Skin landmarks and incision: Ensure that the bladder is completely drained of urine. Starting on one inner thigh, palpate the notch along the lateral edge of the ischiopubic ramus where the adductor longus tendon and the inferior pubic ramus meet. Immediately below this notch, at the level of the clitoris, infiltrate with vasoactive local anesthetic (e.g., 1% lidocaine or 0.25% marcaine with epinephrine) and make a small vertical stab incision in the skin close to the bone, using a no. 15 blade so the curved needle passer can be inserted. Repeat this on the other inner thigh.
Outside to inside needle pass ( Fig. 100.2 ): If starting on the patient’s left side, hold the needle in the right hand at a 45-degree angle and insert the point of the needle into the left obturator incision. Push the needle into the incision to pierce the gracilis and adductor brevis muscles. Avoid any contact of the needle and subsequent sling with the adductor longus tendon, which can cause postoperative pain syndromes. Insert left index finger into the vaginal incision. Staying medial and close to the bone, rotate the needle tip onto your left finger tip, perforating the obturator externus, obturator membrane, obturator internus, and periurethral endopelvic fascia. It is imperative to remain close to the bone on the inner aspect of the obturator foramen at all times in order to avoid the more cephalolaterally situated obturator nerve and vessels coursing through the obturator canal. Guide the needle out of the incision with the left index finger, protecting the urethra and preventing accidental perforation of the vaginal mucosa in the left lateral fornix. Repeat this sequence on the opposite side.