Strategies can help avoid midurethral sling complications

Brisbane, Australia-Failure of midurethral sling surgery is often blamed on poor surgical technique, inappropriate indications for surgery, or the sling material itself, according to Cindy Amundsen, MD, associate professor of urogynecology at Duke University Medical Center, Durham, NC. Nevertheless, surgeons can take a number of steps to avoid failure and minimize complications.

"Why are we still having problems with mid-urethral sling surgery?" she asked.

Dr. Amundsen described a cadaver study that investigated whether the surgical approach affected the types of intra-operative injuries reported. Trocars were placed transvaginally at various angles. The researchers found that deviating too far laterally and cephalad can cause bowel or vascular damage (Obstet Gynecol 2003; 101:933-6).

"Conversely, a trans-abdominal approach may be related to more bladder injuries," she said, adding that a lack of maneuver-ability of the trocar against the abdominal wall may contribute to this problem.

A trans-vaginal approach to trocar placement may help avoid intra-operative bleeding if the trocar is guided directly behind the symphysis pubis and lateral deviations are avoided. Bleeding in the retropubic space can be avoided by emptying the bladder before passage of the trocar and sling material, according to Dr. Amundsen. Trans-vaginal and trans-abdominal compression also will reduce retropubic bleeding.

Protecting the bladder

Bladder perforation may be prevented by employing a trans-vaginal or a transobturator technique for passing the trocar, Dr. Amundsen suggested. However, if a bladder perforation occurs, it must be identified intra-operatively, she said. The trocar should then be replaced and correct placement verified by cystoscopy.

In a Duke University study, practice patterns were surveyed by academic urogynecologists and urologists who perform minimally invasive sling procedures. More than half of each group responded that they would leave an indwelling Foley catheter in for 48 to 72 hours after surgery if a bladder injury occurred during a procedure.

"Because bladder perforation is a common intra-operative complication, a cystoscopic evaluation, whether you do a trans-abdominal, trans-vaginal, or transobturator, is a mandatory part of the procedure," Dr. Amundsen said. "Not only are you going to examine for bladder and urethral mucosal integrity, I also like to look at how close my trocar or sling is to the bladder mucosa. If I can see the sling or trocar through the bladder mucosa, I would recommend you remove the trocar."

This is done to avoid subsequent bladder erosion, which sometimes occurs when slings have been placed too close to the bladder mucosa, she said.

Lowering erosion rates

Lower erosion rates have been associated with mesh slings containing a macroporous monofilament, and most slings now have this characteristic, she said.

"The complication [rates] of vaginal or urinary tract erosion-2% to 5%-are clearly lower than erosion rates in previously used synthetic materials," Dr. Amundsen said. "How can you avoid transvaginal erosion? Performing a meticulous vaginal dissection to create the tunnel is very important, as is guiding the trocar into the tunnel."

However, if a buttonhole tear occurs in the vaginal epithelium, it can be surgically repaired, so it is important that it be discovered intra-operatively, she added.

In the event of a vaginal erosion, most women exhibit such postoperative symptoms as bleeding, discharge, or dyspareunia, Dr. Amundsen said. If the erosion is a small amount (<1 cm) and if it is found early in the postoperative period, it usually will heal spontaneously. If the extrusion is larger or if it is discovered later, the area may require resection, Dr. Amundsen explained.

Urethral erosion can occur up to 1 year postoperatively, she noted.