Canadian women who received vaginal mesh slings to treat incontinence had a one in 30 chance they would need to have that mesh removed or undergo further surgery within 10 years, a new study has found.

Overall, the authors say the risk of needing a second surgery to treat complications from vaginal mesh is “low.”

They note though that the women in their study who received additional slings when the initial one fails had a nearly five-fold increased risk of complications that required even more surgery.

The study, from researchers at the Institute for Clinical Evaluative Sciences (ICES), is the first to measure the rate of mesh removal or revision among Canadian women.

Researchers looked at nearly 60,000 women in Ontario who had undergone surgery between 2002 and 2012 to treat “stress urinary incontinence” – a condition in which women leak urine when they cough, sneeze, or are physically active.The condition is common in women over 50, and while the causes vary, they include vaginal delivery during childbirth.

For some women, pelvic floor muscle exercises can help with the condition as can some lifestyle changes. But for others, the condition is so disruptive, surgery is recommended.

Over the past 20 years, vaginal mesh slings have become the most common surgical treatment for the condition. The slings, made of a polypropylene material, are surgically implanted in the vaginal wall to create a sort of "hammock" under the urethra or bladder neck. The sling supports the urethra and helps to keep it closed.

Senior author Dr. Blayne Welk, a urologist and adjunct scientist at ICES Western and St. Joseph's Health Care in London, Ont., tells CTV News that a number of women have had “excellent success from this procedure.”

But in some women, the slings can erode, leading to vaginal pain. Pieces of the mesh can also find their way into the urinary system, leading to pain while emptying the bladder. These complications can be challenging to treat, and often require further surgery. Welk says for some of these patients, “there is not a lot that surgeons can do.”

In the United States, more than 50,000 women have joined class-action lawsuits for vaginal mesh complications.

Welk says results from their study suggest the risk for complications appears to rise the longer the mesh is in place.

“The rate of complications at a year is about one per cent and then it slowly increases over time,” he told CTV London.

After 10 years, the study found that one in 30 women required mesh revision or removal surgery.

Women who have had surgeries to implant a second or third mesh implant had a much higher risk for complications. The authors say that finding should “temper the enthusiasm” of previous studies that suggest the use of multiple slings is safe and effective

Health Canada and the U.S. FDA have acknowledged the risks of vaginal mesh. The majority of this risk has been attributed to the use of vaginal mesh for prolapse surgery, but the authors say stress incontinence mesh can lead to complications as well.

The researchers found that surgeon experience was a notable factor in the risk for complications. The patients of surgeons who did the most mesh incontinence surgeries had a 27 per cent lower chance of needing mesh removal or revision than other patients.

The researchers say their findings support statements from Health Canada and the FDA that advise that patients be counselled that serious complications can occur with mesh-based stress urinary incontinence procedures and that surgeons should achieve expertise in the procedure.

“I think the most important thing is for patients to educate themselves about the potential risks associated with the procedure and to have a discussion with their surgeon about the risks and benefits of the treatment,” Welk said.

The full study results appear in the journal JAMA Surgery.