The U.S. Food and Drug Administration has ordered Boston Scientific Corp., C.R. Bard Inc. and 31 other companies to conduct three years of trials on safety and effectiveness. These post-market studies of surgical mesh used in vaginal surgeries will hopefully shed light on current concerns over complications such as fistulas. An FDA report in July found a fivefold jump in deaths, injuries or malfunctions tied to the products.

Almost 300,000 synthetic meshes were implanted in U.S. women in 2010 to treat incontinence or shore up pelvic muscles, the agency estimates. The devices' alleged failures have spurred more than 650 lawsuits against manufacturers and heightened scrutiny of the FDA program that cleared the products for sale without human testing.

The agency said that it had sent letters to the 33 manufacturers of urogynecologic surgical mesh devices on Tuesday ordering them to conduct 88 post-market surveillance studies, known as 522 studies, to help the FDA better understand adverse events associated with the devices.

The letters ask each manufacturer to collect data on the results and potential complications of transvaginal procedures, in which the hammock-like meshes are threaded in place through an incision in the vagina. The FDA said in July that it wasn't clear from available studies whether the devices provided a benefit over older methods in certain cases.