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FDA

Published On February 28, 2019

BASIC RESEARCH

What Comes After Transvaginal Mesh?

Prolapse of the pelvic organs is uncomfortable and widespread, and its treatments are sometimes dangerous. But new approaches are on the way.

During pregnancy and childbirth, muscles in the pelvis frequently become stretched and weakened. Nearby organs can later shift out of position, often leading to incontinence, pain and difficulty having intercourse. The problem is alarmingly widespread. About one in three women will experience pelvic organ prolapse (POP) in her lifetime, and by the age of 80, more than one in 10 women will choose surgery to address it.

Surgery, though, can cause more problems than it solves. Some procedures use transvaginal mesh, a device approved in 1996 by the Food and Drug Administration to hold vaginal walls in place. In 2008, the FDA issued a public health notice that, over the course of three years, transvaginal mesh surgery had been associated with more than 1,000 serious complications, including organ perforation and severe pelvic pain. By 2011, 3,000 more cases had been reported, and the FDA flagged the surgery as “an area of continuing serious concern,” reclassifying the mesh in 2016 as a “high-risk device.” In February 2019, the agency convened an advisory committee meeting to discuss the safety and effectiveness of the procedure.

The United Kingdom, Australia, New Zealand and other nations have banned surgical mesh for the treatment of POP. It remains legal in the United States, though many practitioners shy away from its use, and some transvaginal mesh devices are no longer widely available. Still, the conditions that lead to surgery have not gone away, and a search for alternatives has been slowly gaining momentum.

One approach is to make the transvaginal mesh itself safer. Consisting of a knitted sheet usually made of polypropylene, the mesh is fairly reliable for hernia repair and other purposes, but it often buckles or collapses in the vagina when supporting the pelvic floor.

At Magee-Womens Research Institute in Pittsburgh, obstetrician Pamela Moalli and bioengineer Steven Abramowitch are making meshes out of viscoelastic polymer, a lightweight, elastic material that they hope will be more durable and resilient. They are also experimenting with 3D modeling that lets them customize the fit for each patient. Tissue scientists at the University of Sheffield in England are looking into a softer, flexible mesh made of polyurethane as another alternative.

Another promising approach uses stem cells, which may help integrate a mesh device into the vaginal wall and also repair damaged muscles nearby. A team led by stem-cell researcher and reproductive biologist Caroline Gargett at the Hudson Institute of Medical Research in Melbourne, Australia, has led the way. “Our lab had made several discoveries about the stem cells in the uterine lining (endometrium), which are responsible for growing tissue each month in the menstrual cycle,” Gargett says. “I thought that combining the mesh with these endometrial mesenchymal stem cells (eMSCs) might be a way to improve success rates in helping women with POP.”

Gargett’s team found that implanting a modified nanofiber mesh embedded with eMSCs in a mouse model had multiple benefits, markedly improving integration of the implant and reducing immune system rejection. Gargett says she believes that using a woman’s own uterine eMSCs could also help lessen the risk of rejection of the mesh.

Other teams are looking at how to address prolapse without mesh. Israeli company POP Medical Solutions has developed a device made of nitinol, a metal alloy with elastic properties. The device has two main elements: an anchor unit and a delivery system. The delivery system guides the anchor through the vaginal wall to attach to the cervix, where it can draw the uterus back into position. It can be put in place using only local anesthetic, but the majority of surgeries so far have been conducted using general anesthesia.

Physicians are also looking hard at nonsurgical options, as patients might be able to rehabilitate a mild prolapse through physical therapy. “More than 80% of my patients go to physical retraining or rehabilitation and do pelvic floor exercises independently,” says Milena Weinstein, a urogynecologist and pelvic reconstructive surgeon at Massachusetts General Hospital. This includes exercises that strengthen the muscles of the pelvic floor. “If the prolapse is not symptomatic, the best approach is no surgery,” Weinstein says.

But for those who suffer the more severe and uncomfortable symptoms of POP, the near future is a waiting game, to see which of the several approaches now being developed proves most effective. “This problem troubles an enormous number of women,” Gargett says. “It’s high time that we found solutions that work and do not cause harm.”