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DESCRIPTIONAnal fistula plugs are biosynthetic devices used to promote healing and prevent recurrence of anal fistula. The conical shaped plug is anchored in the anal fistula and acts as a scaffold into which new tissue can grow to close the fistula. The plug is absorbed into the body in 6 to 8 weeks. The procedure may require 12 - 24 hours observation post-operatively. The procedure can be repeated in case of failure.
An anal fistula is an abnormal communication between the interior of the anal canal or rectum and the skin surface. Rarer forms may communicate with the vagina or other pelvic structures, including the bowel. Most fistulas begin as anorectal abscesses, which are thought to arise from infection in the glands around the anal canal. When the abscess opens spontaneously into the anal canal (or has been opened surgically), a fistula may occur. Studies have reported that 26% to 37% of cases of perianal abscesses eventually form anal fistulas.
Other causes of fistulas include tuberculosis, cancer, prior radiotherapy, and inflammatory bowel disease. Fistulas may occur singly or in multiples. Symptoms include a purulent discharge and drainage of pus and/or stool near the anus, which can irritate the outer tissues causing itching and discomfort. Pain occurs when fistulas become blocked and abscesses recur. Flatus may also escape from the fistulous tract.
The most widely used classification of anal fistulas is the Parks’ classification system, which defines anal fistulas by their position relative to the anal sphincter as trans-sphincteric, intersphincteric, suprasphincteric, or extrasphincteric. More simply, anal fistulas are described as low (present distally and not extending up to the anorectal sling) or high (extending up to or beyond the anorectal sling). The repair of high fistulas can be associated with incontinence. Diagnosis may involve a fistula probe, anoscopy, fistulography, ultrasound, or magnetic resonance imaging.
Treatment is aimed at repairing the fistula without compromising continence.
Surgical treatments for anal fistulas include fistulotomy/fistulectomy, endorectal/anal sliding flaps, ligation of the intersphincteric fistula tract (LIFT) technique, seton drain and fibrin glue. Fistulotomy involves division of the tissue over the fistula and laying open of the fistula tract. Although fistulotomies are widely used for low fistulas, lay-open fistulotomies in high fistulas carries risk of incontinence. A seton is a thread placed through the fistula tract for the purpose of draining fistula material and preventing the development of a perianal infection. Draining setons can control sepsis but few patients heal after removal of the seton, and the procedure is poorly tolerated long term. A “cutting seton” refers to the process of regular tightening of the seton to encourage gradual cutting of the sphincteric muscle with subsequent inflammation and fibrosis. Cutting setons can cause continence disturbances. Endorectal advancement flaps involve the advancement of a full or partial thickness flap of the proximal rectal wall over the internal (rectal) opening of the fistula tract. The LIFT technique involves identifying the intersphincteric plane and then dividing the fistula tract; its use has been reported in small studies, but long-term follow-up is unavailable. Fibrin glue is a combination of fibrinogen, thrombin, and calcium in a matrix, which is injected into the fistula track. The glue induces clot formation within the tract, which is then closed through overgrowth of new tissue.
Fistula plugs are designed to provide a structure that acts as a scaffold for new tissue growth. The scaffold, which can be derived from animal (eg, porcine) tissue or a synthetic copolymer fiber, is degraded by hydrolytic or enzymatic pathways as healing progresses. The plug is pulled through the fistula tract and secured at the fistula’s proximal opening; the fistula tract is left open at the distal opening to allow drainage.
The SIS Fistula Plug from Cook Biotech received 510(k) clearance from the Food and Drug Administration (FDA) in March 2005 based on similarity to predicate devices, including the SURGISIS® Soft Tissue Graft and the STRATASIS® Urethral Sling, both manufactured by Cook Biotech Incorporated.
The SIS Fistula Plug is manufactured from porcine small intestinal submucosa (SIS) and is intended for repair of anal, rectal and enterocutaneous fistulas. The modified SIS Fistula Plug, also manufactured from porcine small intestinal submucosa, is supplied in a tapered configuration with a button to provide increased retention of the plug and improved blockage of the fistula. It received 510(k) clearance in October 2006. In March 2009, W.L. Gore & Associates received 501(k) clearance for the BIO-A® Fistula Plug intended for use in anorectal fistulas. The GORE BIO-A® Fistula Plug device is comprised of a hydrolytic and enzymetic pathways, the same material, technology and three-dimensional disk with tubes mesh design as the predicate GORE Bioabsorbable Mesh hernia plug device. The indications for use and performance of the GORE BIO-A® Fistula Plug are substantially equivalent to the predicate Cook SIS Fistula Plug.
POLICYBiosynthetic fistula plugs, including plugs made of porcine small intestine submucosa or of synthetic material are considered investigational for all indications including, but not limited to, repair of anal and rectal fistulas.
POLICY EXCEPTIONSFederal Employee Program (FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
POLICY GUIDELINESInvestigative service is defined as the use of any treatment procedure, facililty, equipment, drug, device or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member’s specific benefit plan language.
POLICY HISTORY04/20/2010: New policy added.
07/29/2011: Policy reviewed; no changes.
07/17/2012: Policy reviewed; no changes.
11/15/2013: Policy reviewed; no changes.
12/02/2014: Policy reviewed; description revised. Policy statement unchanged.
SOURCESBlue Cross Blue Shield Association Policy # 7.01.123
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.