Prolapse repair moves toward tissue replacement: synthetic and xenogenic products.
In the past 7 years, site-specific repairs that use the tissue involved in the actual defect have become the most popular surgical treatment for pelvic organ prolapse. These repairs fail in about 24% of the cases at his clinic, said Dr. Ross, one of the early leaders in pelvic reconstructive surgery.
That "extremely high" failure rate echoes the recurrence rates seen 10-12 years ago in general surgery for inguinal or ventral wall hernias. Since then, surgeons have reduced failure rates for those procedures to 2%-4%. "They stopped using the poor in situ tissue and went to tissue replacement. I feel that's where gynecology is going to now," said Dr. Ross of Salinas, Calif.
Several synthetic and xenogenic products are available from competing manufacturers.
A study soon to be published by Dr. Ross and his associates found that 7% of monofilament meshes eroded during nearly 10 years of follow-up in 51 posthysterectomy patients who underwent pelvic organ prolapse repair. Similar erosion rates have appeared in the published studies so far, nearly all of which involved Prolene mesh.
With newer and better polyfilament polyester meshes available, there's no good reason to work with the more difficult Prolene mesh, he noted.
Some of the newer meshes come with a coating of hydrophilic type 1 collagen on one side that prevents adhesions to bowel and other tissues. Dr. Ross soon will start testing a composite polyfilament mesh coated with collagen on both sides, which may be even more protective, he said.
The larger porosity of some polyfilament meshes reduces the encapsulation and scarred bonding seen with synthetic meshes, which are undesirable traits when repairing functional tissue like the vagina. "Don't pick your meshes lightly. Look into them" to select one with properties that best suit your goals, said Dr. Ross, also of the University of California, Los Angeles.
For example, if strength is the key goal, consider a synthetic mesh, which may be stronger than xenogenic products. The downside is that synthetic meshes are prone to erosion.
Erosions led Dr. Ross to incorporate xenogenic materials into his repairs, often in combination with synthetic mesh, to create a dual synthetic-xenogenic mesh, which he called "'a classic example of bioengineering." Xenogenic materials become incorporated into the host tissue and the synthetic mesh is used for attachment and support.
Dr. Ross is involved in an ongoing trial comparing two porcine xenogenic meshes for anterior and posterior vaginal wall repairs: a dermis patch and small intestine submucosa (SIS). Both meshes consist of an acellular collagen matrix with a high tensile strength. The porcine dermis persists after merging with the host tissue, acting as a scaffold, and can always be felt. The SIS is replaced by the host tissue and new tissue growth is stimulated, which may even thicken the vaginal wall, he said.
In 6-44 months of follow-up on 86 patients who underwent anterior or posterior vaginal repair for stage II or greater pro-lapse, two of the porcine dermis meshes eroded and were treated medically with intensive estrogen cream therapy.
There have been no symptomatic prolapse recurrences, said Dr. Ross, who has no financial affiliation with the companies that make the products he discussed.
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|Publication:||OB GYN News|
|Date:||Dec 15, 2003|
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