One of the most common reasons I see patients in my office is for Stress Incontinence (SUI). This is urinary leakage which occurs with increases in abdominal pressure often occurring with coughing, sneezing, laughing, or exercising. With an estimated 15 million American women reporting stress incontinence, the number of patients in my office is no surprise. It is also natural that surgical therapy for Stress Incontinence would be common and over 200,000 operations are performed each year in the US. But changes in the treatment of bladder prolapse (a different issue from stress incontinence) including actions taken by the FDA over the last decade have meant considerable confusion for people who are considering surgical management of Stress Incontinence. Though there are certainly similarities between vaginal mesh used to treat prolapse and synthetic slings used for SUI, the differences are considerable and extremely important to anyone considering their options. Today I’ll answer some of the most common questions I hear in my practice.

What are synthetic slings made from?

Synthetic slings are made of a material called polypropylene that is used in other surgical specialties for things like hernia repair and transplant surgery. This material has been used for these purposes for over 50 years. Slings to treat SUI have been made of polypropylene and have been widely used in the United States for over 20 years. This provides us with a long history to evaluate both short-term and long-term improvement as well as risks of complications. We don't have to wonder how slings might change in the body over the next 20 years because we can see the results in patients who have had them for the last 20 years. You may be very interested to note that vaginal mesh that was used to treat pelvic prolapse is also created from polypropylene. However, the differences in risks and complications between the two types of devices may have more to do with how it is used rather than what it is made from. Mid-urethral slings may be made of the same material as prolapse mesh, but its use is dramatically different.

What are the concerns about vaginal mesh?

Types of surgical mesh, including polypropylene, have been used since the 1950’s for various medical uses including abdominal surgery. Use in vaginal prolapse surgery came later and in 2002, the first polypropylene mesh device was cleared by the FDA for use in repair of vaginal prolapse. But between 2002 and 2011, the FDA noted that higher numbers of surgical complications were seen with mesh products used to treat vaginal prolapse through a vaginal incision than had been expected. Some of the discrepancy may have been because these devices were initially compared to slings for stress incontinence, which have lower rates of serious complications. By 2011, the FDA requested more information about the safety of these prolapse devices and began to warn the public that vaginal mesh to treat prolapse may carry higher risks than previously thought. In 2016, the FDA went further and changed the classification of the devices from a moderate-risk category to a high-risk category and required manufacturers to conduct new studies designed to assess whether the devices were safe for use. It should be noted that the FDA explicitly stated at that time that these orders did not apply to synthetic slings used to treat stress incontinence.

In April 2019, the FDA took the fairly surprising step of ordering the immediate removal of all transvaginal mesh products, reporting the FDA had not received sufficient additional data to assure the safety and efficacy of the devices. Women with an existing implant were advised that there was no need for any additional action if they were not having any symptoms. Again, there was no additional restriction placed on synthetic slings for SUI at that time. Nonetheless, this has caused considerable confusion for many women I see who are concerned about the safety of synthetic slings for SUI.

How are slings for incontinence different from mesh for prolapse?

Using synthetic mesh to repair prolapse is very different from using it to treat incontinence. How is it different? In pelvic prolapse, the wall of the vagina is pushed out by the bladder, the intestines, or the uterus. Using mesh to repair this "pushed out" vaginal wall meant using the mesh to pull these tissues back into place. Pulling on tissue means tension. And tension results in very specific risks when using a synthetic material, including higher risks of pain. Stress Incontinence slings are meant to support the urethra but not to place any tension on the tissue. It acts like a net to catch a "falling" urethra (urethral hypermobility) to help with incontinence. It does not have to pull the urethra back into place as we do with prolapse. Because there should be no tension on the urethra, the risk of pain and damage to the tissues is much different than what we see in mesh used to treat vaginal prolapse. Very different uses mean very different risks.

The amount of mesh used and where it is located is also a difference between the two. Vaginal mesh used to treat prolapse used larger sheets of woven polypropylene spread throughout the vagina. The mesh of a synthetic sling, particularly the part of the sling located in the vagina, has a much smaller area, possibly responsible for its lower rates of exposure (when you can see or feel mesh inside the vagina).

How can I know that slings for incontinence are safe?

Synthetic mid-urethral slings to treat SUI have been analyzed in over 2,000 publications since the early 1990s. I am not aware of any class of surgical devices that has been studied that extensively. After 20 years of experience and testing, we have learned that mid-urethral slings are at least as effective as any other Stress Incontinence surgery and are associated with less pain, shorter time in hospital, and faster return to normal activity than the alternative surgeries. They are considered the gold-standard treatment of stress incontinence today and are by far the most common surgery for SUI.

The safety and effectiveness of mid-urethral slings reflected by the FDA statements regarding their use. Even while the FDA moved to restrict in 2016 and later remove in 2019 vaginal prolapse mesh, they chose not to alter their recommendations on the use of synthetic slings to treat incontinence. While it may be the same material, it is used in a very different way and this matters a lot. For my patients who are concerned about the safety of slings to treat their SUI, we always review all risks of sling surgery. But I note that the alternative procedures have similar risks, sometimes with less effectiveness. I ask them to consider their concerns about risks versus the amount of improvement they expect to see and how bothered they are by their incontinence. This balance helps them to make an informed decision. While some may choose to avoid surgery, many feel that the benefits outweigh the risks for them.

So, are there any risks for synthetic slings?

Absolutely. In fact, in addition to the risks that are typical of almost any incontinence surgery, the synthetic mid-urethral slings have risks that are unique to them. The important point is not that there are no risks, there are. Rather, it is that mid-urethral slings offer a good balance between risk and effectiveness. The most common side effect of synthetic sling surgery is urinary frequency and urgency that begins after surgery. Possible causes of this can include irritation from the surgery or compression of the urethra by the sling. Irritation from the surgery will often improve over the first few weeks after surgery; compression of the urethra will not. It can be difficult to even know if urinary frequency or urgency is associated with surgery if a patient already had these symptoms before. This is one of the many reasons it can be helpful to have a diary of voiding and incontinence before ever proceeding with treatment.

Problems Urinating

Occasionally, either a sling is put in tightly or it contracts as part of healing and will compress the urethra. A woman’s bladder is not typically required to push against a significant constriction and can react in a variety of ways. Women with blockage from a sling may note a decrease in the force of their stream or a need to push with the stomach muscles to try to empty their bladder. Other women will react to an obstructing sling with new or worsening uncomfortable urinary urgency or frequent urination. Some will even be unable to empty their bladders completely. Compression of the urethra by a sling serious enough that we have to act occurs about 1-3% of the time, in my experience. Most of the time if the sling is tight enough against the urethra that you are having bothersome symptoms that last for weeks after surgery, the best course is to cut the sling just underneath the urethra. This will loosen the sling and relieve the obstruction. Sling incision like this can result in a return of Stress Incontinence but most patients will not have enough SUI to warrant a repeat surgery.

Sling Exposure

We take great care to fully cover a sling with a healthy layer of vaginal tissue. Since slings are made of a synthetic material, exposure of the sling can result in infection of that portion of the sling as well as discomfort for the woman or her sexual partners. Sometimes, if the area of exposure is very small (<1 cm) we can help the vaginal tissue heal over the sling by using estrogen cream. However, if the exposure is larger, this often requires the removal of that portion or all of the sling. Removing a portion of the sling can result in a return of stress incontinence. I see vaginal exposure in less than 1% of the sling surgeries I have performed but it is still a possibility with any sling surgery. The rates of sling exposure are likely lower than what was previously seen with vaginal mesh for prolapse.

Perforation

An uncommon complication of slings is injury to the bladder during passage of the sling. However, during sling surgery, a small scope can be placed in the bladder to check for any injury to the bladder. This reduces the risk of sling passage through the bladder, though it is difficult to say that it eliminates it entirely. Another complication of retropubic and pubovaginal slings is damage to the intestines. This is a very serious complication that is fortunately very rare.

Pelvic Pain

While complications like sling exposure are unique to synthetic slings, other complications like trouble urinating and pelvic pain can occur with almost any incontinence surgery. After any incontinence procedure, patients may report pelvic pain, including vaginal pain. This pelvic pain may occur on its own or may be associated with intercourse (called dyspareunia). In some cases, the vaginal pain appears to result from sling exposure with infection or a sling that is too tight. If the pain can be traced to this, it is possible to remove the exposed portion of the sling or to cut a sling that is too tight. This can often relieve some or all of the vaginal pain. However, it is possible for patients with a sling that is neither too tight nor exposed to still have pelvic pain after sling surgery. When I see this, there is often dysfunction of the pelvic muscles and pelvic floor physical therapy can be very useful.

How do I know if a sling surgery is right for me?

Unlike more conservative therapies such as pelvic floor (Kegel) exercises, surgery to treat Stress Incontinence (SUI) carries certain risks. Because of these risks, the consideration of surgery should always take into account how bothersome your symptoms are and how much they affect your life. The amount and frequency of any stress leakage can be useful in determining how much improvement you can expect from a procedure. If you have minimally bothersome symptoms, you are less likely to see much of a benefit from surgery and may be unwilling to accept even the relatively low risks of surgical therapy. If you have symptoms that have a greater effect on your lifestyle, you are more likely to see substantial benefit from surgery and may be more willing to accept any risks. There are always other alternatives to sling surgery for SUI but it is important to balance the risks of surgery with the effectiveness that it can provide. Luckily, mid-urethral slings are a generally safe and effective therapy for SUI in patients who have not seen satisfactory improvement with more conservative measures.