Background

Anal Fistulas

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 in 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.^1,

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 transsphincteric,  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

Treatment is aimed at repairing the fistula without compromising continence.

Surgical treatments for anal fistulas include fistulotomy or fistulectomy, endorectal or anal sliding flaps, ligation of the intersphincteric fistula tract technique, seton drain, and fibrin glue. Fistulotomy involves a 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 carry the risk of incontinence. A seton is a thread placed through the fistula tract to drain 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 the 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 intersphincteric fistula tract 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.^2, Fibrin glue is a combination of fibrinogen, thrombin, and calcium in a matrix, which is injected into the fistula tract. The glue induces clot formation within the tract, which is then closed through the overgrowth of new tissue.

Fistula Plugs

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 (e.g., 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. Several fistula plugs have been cleared for marketing by the U.S. Food and Drug Administration (see Regulatory Status section).

A fistula plug derived from autologous cartilage tissue has been investigated in a small (n=10) pilot study.^3,

Regulatory Status

Several plugs for fistula repair have been cleared for marketing by the U.S. Food and Drug Administration through the 510(k) process and are outlined in Table 1.

Table 1. Devices for Anal Fistula Repair

Device	Year	Description	Indication(s)	Predicate Device(s)	FDA Product Code
SIS Fistula Plug (Cook Biotech)	Mar 2005	Manufactured from porcine SIS	Repair of anal, rectal, and enterocutaneous fistulas	Surgisis® Soft Tissue Graft (Cook Biotech) Stratasis® Urethral Sling (Cook Biotech)	FTM
Surgisis RVP Recto-Vaginal Fistula Plug (Cook Biotech)	Oct 2006	Manufactured from porcine SIS Tapered configuration with a button to increase plug retention and improve fistula blockage	Reinforce soft tissue to repair rectovaginal fistulas	SIS Fistula Plug (Cook Biotech)	FTM
Surgisis Biodesign Enterocutaneous Fistula Plug (Cook Biotech)	Feb 2009	Manufactured from porcine SIS Tapered configuration with flange to increase plug retention and improve fistula blockage	Reinforce soft tissue to repair enterocutaneous fistulas	SIS Fistula Plug (Cook Biotech)	FTM
Gore Bio-A Fistula Plug (W.L. Gore & Associates)	Mar 2009	Manufactured from bioabsorbable PGA:TMC copolymer Supplied in a 3-dimensional configuration of a disk with attached tubes	Reinforce soft tissue to repair anorectal fistulas	Gore Bioabsorbable Mesh (W.L. Gore & Associates) SIS Fistula Plug (Cook Biotech)	FTL
Biodesign Anal Fistula Plug (Cook Biotech)	May 2016	Manufactured from porcine SIS Additional wash steps added in processing	Reinforce soft tissue where a rolled configuration is required to repair anal, rectal, and enterocutaneous fistulas	SIS Fistula Plug (Cook Biotech)	FTM

FDA: Food and Drug Administration; PGA:TMC: polyglycolide-co-trimethylene carbonate; SIS: small intestinal submucosa.

Related Policies

• None

To assess whether the evidence is sufficient to draw conclusions about the net health outcome of technology, two domains are examined: the relevance, and quality and credibility. To be relevant, studies must represent one or more intended clinical use of the technology in the intended population and compare an effective and appropriate alternative at a comparable intensity. For some conditions, the alternative will be supportive care or surveillance. The quality and credibility of the evidence depend on study design and conduct, minimizing bias and confounding that can generate incorrect findings. The randomized controlled trial (RCT) is preferred to assess efficacy; however, in some circumstances, nonrandomized studies may be adequate. RCTs are rarely large enough or long enough to capture less common adverse events and long-term effects. Other types of studies can be used for these purposes and to assess generalizability to broader clinical populations and settings of clinical practice.

Anal Fistula Repair

Clinical Context and Therapy Purpose

The purpose of placing anal fistula plugs (AFPs) in patients who have anal fistulas is to provide a treatment option that is an alternative to or an improvement on existing therapies.

The question addressed in this policy is: Does the use of AFPs improve the net health outcome in those with anal fistulas?

The following PICOs were used to select literature to inform this policy.

Patients

The relevant population of interest are patients with anal fistulas.

Interventions

The therapy being considered is an AFP.

Anal plugs are placed by a surgeon under general anesthesia in an outpatient surgical center setting.

Comparators

The following therapies are currently being used to treat anal fistulas: fistulotomy or fistulectomy, endorectal or anal sliding flaps, seton drains, and fibrin glue.

Outcomes

The general outcomes of interest are fistula repair and healing, elimination of symptoms, treatment-related complications (e.g., abscess), and fistula recurrence.

Short-term postsurgical follow-up can range between 2 and 12 weeks while longer-term follow-up monitoring can range from weeks to months.

Systematic Reviews

Narang et al (2016) published a systematic review of the Gore Bio-A plug for anal fistulas, which included 6 studies (total n=221 patients) in a qualitative synthesis.^4, Fistula healing rates ranged from 15.8% to 72.7%. Reviewers assessed the overall quality of the underlying studies as poor.

Nasseri et al (2016) reported on a systematic review of AFP for patients with Crohn disease and anal fistulas.^5, Twelve studies were included: 8 nonrandomized prospective studies and 4 retrospective studies (total n=84 patients; range, 1-20 per study). Due to study heterogeneity, reviewers did not perform a weighted analysis with summary efficacy estimates. The total success rate of AFPs was 49 (58.3%) of 84 placed (95% confidence interval [CI], 47% to 69%).

Xu et al (2016) reported on a meta-analysis of 10 comparative studies of AFPs and mucosal advancement flaps (MAFs) for complex anal fistulas (total n=778 patients).^6, Three studies were randomized trials; the remaining were observational studies or did not describe designs. In the pooled analysis, there were no significant differences in healing rates at the end of follow-up between the AFP and MAF groups (odds ratio [OR], 0.79; 95% CI, 0.36 to 1.73; p=0.55, I²=74%). None the 7 studies reporting on recurrence rates found significant differences in rates (OR=2.29; 95% CI, 0.59 to 8.88; p=0.23, I²=83%). However, conclusions were limited by shortcomings in the underlying evidence base.

Cirocchi et al (2013) published results of a systematic review and meta-analysis of studies that compared biologically derived products for fistula repair, including fibrin glue, AFPs, and acellular dermal matrix, with surgical therapy for fistula repair.^7, Seven studies met eligibility criteria, 4 of which compared AFPs with surgery and 2 of which were RCTs (van Koperen et al [2011]^8, and Ortiz et al [2009]^9, are described in the Randomized Controlled Trials section). In the combined analysis, AFP placement did not differ significantly from surgical treatment on rates of healing (relative risk, 1.19; 95% CI, 0.51 to 2.76). Recurrence of anal fistulas did not differ significantly between patients treated with AFP and those treated with surgery, although the CI for the pooled analysis was very wide (OR=3.12; 95% CI, 0.52 to 18.83).

In 2012, 3 reviews compared AFP with conventional surgical treatment for anal fistulas.^10,11,12, Pu et al (2012) undertook a meta-analysis of 5 studies (2 RCTs, 3 retrospective studies) published through April 2012. Treatment options in the conventional arm included endorectal or MAFs, fibrin glue, and seton drains.^10, The 2 RCTs included van Koperen et al (2011)^8, and Ortiz et al (2009).^9, On combined analysis (5 studies, 428 patients), AFP patients had a higher recurrence rate (62%) than those undergoing conventional treatment options (47%; p=0.004) after 3-month follow-up (OR=1.91; 95% CI, 1.23 to 2.97).

Leng and Jin (2012) undertook a meta-analysis of 6 studies published through April 2011 (3 RCTs, 2 retrospective studies, 1 cohort study) involving 408 patients comparing AFP with MAF.^11, Two RCTs in this analysis were included in the Pu et al (2012) review (previously described); the third RCT was a Chinese trial of 90 patients comparing AFP (manufactured in China with a design similar to the SURGISIS) with the MAF. On combined analysis, the differences in the overall success rates (6 studies) and incidence of fistula recurrence (4 studies including 3 RCTs) did not differ statistically significantly between AFP and MAF (risk difference, -0.12; 95% CI, -0.39 to 0.14; risk difference, 0.13; 95% CI, -0.18 to 0.43, respectively). However, the risk of continence postoperatively (3 studies including 2 RCTs) was reported to be lower with AFP (risk difference, -0.08; 95% CI, 0.15 to -0.02). In addition to the small numbers of controlled studies and limited follow-ups, the studies in this meta-analysis had significant heterogeneity.

O’Riordan et al (2012) conducted a systematic review of AFP (20 studies including the RCTs by van Koperen et al [2011] and Ortiz et al [2009]) for patients with Crohn and non-Crohn-related anal fistulas.^12, The follow-up period across studies ranged from 3 to 24.5 months. The pooled proportion of patients achieving fistula closure in those with non-Crohn anal fistula (0.54; 95% CI, 0.50 to 0.59) was similar to that in those with Crohn disease (0.55; 95% CI, 0.39 to 0.70). There were no reported cases of significant change in continence after AFP insertion in any study patients (total n=196 patients). Review findings were limited by the variability of operative technique and perioperative care across studies, which may have influenced the probability of success or failure associated with the AFP.

A systematic review by Garg et al (2010) reported a wide range of success rates.^13, In the 12 case series selected, reported success rates for the AFP procedure ranged from 24% to 92%. Success rates in treating complex fistula-in-ano in the 8 prospective studies reviewed were 35% to 87%. The complications rates for abscess formation and/or sepsis ranged from 4% to 29%, and plug extrusion rates ranged from 4% to 41%.

In a Cochrane review of surgical intervention for anorectal fistula, Jacob et al (2010) found few randomized trials comparing surgical repair procedures.^14, The AFP procedure was noted as needing further study with randomized trials.

Section Summary: Systematic Reviews

Several systematic reviews of studies of AFP repair have demonstrated a wide range of success rates and heterogeneity in study results. The net benefit of a strategy using AFPs compared with an open surgical repair is unknown given a lack of high-quality trials and uncertainty related to the tradeoffs between a less invasive procedure and a higher fistula recurrence rate.

Randomized Controlled Trials

Senejoux et al (2016) reported on an RCT comparing AFP with seton removal alone in 106 patients who had Crohn disease with non- or mildly active disease but at least 1 anoperitoneal fistula drained for at least 1 month.^15, The trial was powered for the superiority of AFP, and analysis was intention-to-treat. At 12 weeks of follow-up, in the AFP group (n=54), the clinical remission rate was 31.5% compared with 23.1% in the control group (relative risk, 1.31; 95% CI, 0.59 to 4.02; p=0.19). Fistula tract healing rates on magnetic resonance imaging did not differ significantly between groups at 12 weeks.

Van Koperen et al (2011) reported on a double-blinded, multicenter, randomized trial comparing AFP with MAF in 60 patients with high perianal fistulas.^8, At 11-month follow-up, trialists reported fistula recurrence in 22 (71%) patients in the AFP group and in 15 (52%) patients in the advancement flap group; these rates did not differ significantly (p=0.126). Postoperative pain scores, quality of life after surgery, and functional outcomes did not differ significantly between groups. Despite disappointing results, trialists indicated the plug might be considered as an initial treatment option because the procedure is simple and minimally invasive.

Ortiz et al (2009) compared the use of porcine submucosal (Surgisis) AFPs with an endorectal anal flap (ERAF) procedure in an RCT of 43 patients with high anal fistula.^9, The primary endpoint was fistula healing. Recurrence was defined as the presence of an abscess in the same area or obvious evidence of fistulization. Five patients in the AFP group and 6 in the ERAF group did not receive the allocated intervention, leaving 32 patients. One patient in the AFP group was lost to follow-up. A large number of fistula recurrences in the fistula plug group led to the premature closure of the trial. After 1 year, fistula recurrence was seen in 12 of 15 patients treated with an AFP vs 2 of 16 patients who underwent the flap procedure (relative risk, 6.40; 95% CI, 1.70 to 23.97; p<0.001). A trend for more sphincter involvement and more women in the ERAF group was noted. Complications were not reported.

Section Summary: Randomized Controlled Trials

An RCT has compared AFP with seton drain removal alone for fistulizing Crohn disease, with no significant difference reported between groups. Two relatively small RCTs have compared AFP with surgical flap treatment for anal fistulas, one of which reported significantly higher rates of fistula recurrence with AFP while the other found similar rates of recurrence between AFP and surgical treatment. Larger RCTs are needed to determine the comparative efficacy of AFPs and surgical repair.

Nonrandomized Comparative Studies

Prospective Studies

Hall et al (2014) reported results from a larger multicenter registry study of prospectively collected data for 240 anal fistula surgeries, including those conducted with AFPs.^16, Rates of the utilization of fistulotomy, ligation of the intersphincteric fistula tract technique, advancement flap, AFP placement, draining seton, and cutting seton were 61%, 18%, 6.3%, 4.2%, 8.3%, and 0.83%, respectively. The healing rate for patients treated with AFPs was 20% (95% CI, 5% to 50%) compared with 95% after fistulotomy (95% CI, 89% to 97%), 79% after intersphincteric fistula tract technique (95% CI, 65% to 88%), 60% after advancement flap (95% CI, 33% to 77%), and 100% after cutting seton placement (95% CI, 34% to 100%).

In one of the larger, prospective studies, Hyman et al (2009) reported on outcomes data for various procedures to treat anal fistulas in 245 patients at 13 hospitals.^17, Data were collected as part of a prospective, multicenter outcomes registry. Fistulotomy was the most frequently performed procedure (n=120), followed by fistula plug (n=43), staged fistulotomy (n=36), seton drain only (n=21), cutting seton (n=13), fibrin glue (n=5), and advancement flap (n=4). Three patients were listed as other or unrecorded. At 1 and 3 months, 19.5% and 63.2% of patients were healed, respectively. At 3 months, 32% of fistula plug patients had healed compared with 87% of fistulotomy, 50% of staged fistulotomy, and 5% of seton drain only patients. The authors noted limitations to this registry-based study, including concerns about data entry, lack of standardized surgical procedures, and heterogeneity among patients. The three-month results may also indicate longer healing times might be required.

Retrospective Studies

Several retrospective studies have also compared AFP with alternative treatments. Fisher et al (2015) retrospectively evaluated success rates after AFP (n=31) or endorectal advancement flap (n=40) in patients with anal fistula treated at a single- institution from 2007 to 2012.^18, For patients treated after May 2007; the Surgisis AFP was available. More patients treated with AFP had inflammatory bowel disease (29.0% vs 5.0%; p=0.008). During follow-up, 12 (39%) patients treated with AFP and 17 (43%) treated with endorectal advancement flap had fistula recurrence (OR=0.94; 95% CI, 0.32 to 2.72; p=1.00). Rates of complications did not differ significantly between groups.

Christoforidis et al (2009) retrospectively analyzed patients from a U.S. center with transsphincteric fistulas treated with ERAF (n=43) or anal plug (Surgisis; n=37) between 1996 and 2007.^19, Success was defined as a closed external opening in the absence of symptoms at minimal follow-up of six months. The success rate was 63% in the ERAF group and 32% in the AFP group after a mean follow-up of 56 months (range, 6-136 months) for ERAF and 14 months (range, 6-22 months) for AFP. After the exclusion of patients with early AFP extrusion, which may be considered a technical failure, the ERAF advantage was not statistically significant (p=0.06). Twenty-three of 27 patients who had ERAF and 7 of 12 patients who had AFP responded to a questionnaire addressing functional outcomes. In the ERAF group, 11 of 23 patients had no continence disturbance vs 6 of 7 in the AFP group. The lack of prospectively collected incontinence scores before the procedure, and a low response rate in the AFP group does not permit valid comparisons on functional outcomes. Complication rates were low in both groups; only two patients in the ERAF group required reoperation for bleeding.

Wang et al (2009) compared outcomes for patients who had transsphincteric fistulas treated using an AFP from 2005 to 2006 (n=29) with historical controls treated with ERAF (2001-2005) (n=26).^20, Of 26 initial flap procedures, 10 failed and 16 healed. Of 29 initial plug procedures, 19 failed and 10 healed. In total, 30 advancement flaps and 34 plug procedures were performed (including additional treatments for failed initial procedures). Closure rates were 34% for plugs (mean follow-up, 279 days; range, 110-690 days) and 62% for flaps (median follow-up, 819 days; range, 93-1928 days; p=0.045). Complications were not reported.

A retrospective study of 232 patients treated in Canada between 1997 and 2008 using various methods for high transsphincteric anal fistulas was reported by Chung et al (2009).^21, Postoperative healing rates at the 12-week follow-up for the fistula plug, fibrin glue, flap advancement, and seton drain groups were 59%, 39%, 60%, and 33%, respectively. The closure of the primary fistula opening using an AFP and flap advancement resulted in similar fistula healing rates in this patient group and that these strategies were superior to seton placement and fibrin glue. The 12-week follow-up in this study was likely too short to evaluate the durability of the treatment.

Section Summary: Nonrandomized Comparative Studies

Nonrandomized comparative studies have reported variable rates of healing after AFP compared with other fistula closure methods. These studies are limited by patient heterogeneity and relatively short-term follow-up durations.

Summary of Evidence

For individuals who have anal fistula(s) who receive placement of AFP(s), the evidence includes three RCTs, a number of comparative and noncomparative nonrandomized studies, and systematic reviews of these studies. The relevant outcomes are symptoms, change in disease status, morbid events, functional outcomes, and treatment-related morbidity. Two RCTs comparing AFP with surgical flap treatment have reported disparate findings: one found significantly higher rates of fistula recurrence with AFP; the other found similar rates of recurrence for AFP and surgical treatment. Another RCT that compared AFP with seton drain removal alone for patients with fistulizing Crohn disease, found no significant difference in healing rates at 12 weeks between groups. Systematic reviews of AFP repair have demonstrated a wide range of success rates and heterogeneity in study results. Nonrandomized studies have also reported conflicting results. The evidence is insufficient to determine the effects of the technology on health outcomes.

SUPPLEMENTAL INFORMATION

Clinical Input From Physician Specialty Societies and Academic Medical Centers

While the various physician specialty societies and academic medical centers may collaborate with and make recommendations during this process, through the provision of appropriate reviewers, input received does not represent an endorsement or position statement by the physician specialty societies or academic medical centers, unless otherwise noted.

In response to requests, input was received from 3 physician specialty societies and 5 academic medical centers while this policy was under review in 2013. Input was mixed, with three reviewers agreeing that biosynthetic fistula plugs are considered investigational for all indications while four reviewers considered their use as both investigational and medically necessary. One reviewer disagreed with the policy statement but noted that the success rates of all procedures (including anal fistula plugs) vary widely, as reflected by Horizon BCBSNJ’s review of the literature.

Practice Guidelines and Position Statements

American Society of Colon and Rectal Surgeons

The 2016 practice guidelines on the treatment of anorectal abscess, fistula-in-ano, and rectovaginal fistula from the Society provided a weak recommendation with moderate-quality evidence.^22, With recent evidence of success rates of less than 50% in most studies for the treatment of complex anal fistulas with an anal fistula plug, the guidelines concluded that the fistula plug is relatively ineffective in the treatment of fistula-in-ano.

National Institute for Health and Care Excellence

The National Institute for Health and Care Excellence (2019) updated its guidance on the suturable bioprosthetic plug.^23,The Institute determined that "evidence on the safety and efficacy of bioprosthetic plug insertion for anal fistula is adequate to support the use of this procedure provided that standard arrangements are in place for clinical governance, consent, and audit." Though, it was noted that "the procedure should only be done by a surgeon experienced in managing anal fistulas."

U.S. Preventive Services Task Force Recommendations

Not applicable.

Ongoing and Unpublished Clinical Trials

Some currently unpublished trials that might influence this policy are listed in Table 2.

Table 2. Summary of Key Trials

NCT No.	Trial Name	Planned Enrollment	Completion Date
Unpublished
ISRCTN78352529	Surgisis® anal fistula plug versus surgeon's preference (advancement flap, fistulotomy, cutting seton) for transsphincteric fistula-in-ano: a multicentre phase III randomised controlled trial	306	May 2017 (completed)
NCT01478139	Ligation of Intersphincteric Fistula Tract (LIFT) Versus LIFT-plug Procedure for Anal Fistula Repair: a Multicenter, Randomized, Open-label, Parallel Controlled Trial	240	Nov 2013 (unknown)

NCT: national clinical trial.

^a Denotes industry-sponsored or cosponsored trial.]
________________________________________________________________________________________

Horizon BCBSNJ Medical Policy Development Process:

This Horizon BCBSNJ Medical Policy (the “Medical Policy”) has been developed by Horizon BCBSNJ’s Medical Policy Committee (the “Committee”) consistent with generally accepted standards of medical practice, and reflects Horizon BCBSNJ’s view of the subject health care services, supplies or procedures, and in what circumstances they are deemed to be medically necessary or experimental/ investigational in nature. This Medical Policy also considers whether and to what degree the subject health care services, supplies or procedures are clinically appropriate, in terms of type, frequency, extent, site and duration and if they are considered effective for the illnesses, injuries or diseases discussed. Where relevant, this Medical Policy considers whether the subject health care services, supplies or procedures are being requested primarily for the convenience of the covered person or the health care provider. It may also consider whether the services, supplies or procedures are more costly than an alternative service or sequence of services, supplies or procedures that are at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of the relevant illness, injury or disease. In reaching its conclusion regarding what it considers to be the generally accepted standards of medical practice, the Committee reviews and considers the following: all credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, physician and health care provider specialty society recommendations, the views of physicians and health care providers practicing in relevant clinical areas (including, but not limited to, the prevailing opinion within the appropriate specialty) and any other relevant factor as determined by applicable State and Federal laws and regulations.

___________________________________________________________________________________________________________________________

Index:
Plugs for Anal Fistula Repair
Plugs for Fistula Repair
Fistula Repair
Anal Fistula
SIS Fistula Plug
GORE BIO-A Fistula Plug

References:
1. Simpson JA, Banerjea A, Scholefield JH. Management of anal fistula. BMJ. Oct 15 2012;345:e6705. PMID 23069597.

2. Campbell ML, Abboud EC, Dolberg ME, et al. Treatment of refractory perianal fistulas with ligation of the intersphincteric fistula tract: preliminary results. Am Surg. Jul 2013;79(7):723-727. PMID 23816007.

3. Ozturk E. Treatment of recurrent anal fistula using an autologous cartilage plug: a pilot study. Tech Coloproctol. May 2015;19(5):301-307. PMID 25850629.

4. Narang SK, Jones C, Alam NN, et al. Delayed absorbable synthetic plug (GORE(R) BIO-A(R)) for the treatment of fistula-in-ano: a systematic review. Colorectal Dis. Jan 2016;18(1):37-44. PMID 26542191.

5. Nasseri Y, Cassella L, Berns M, et al. The anal fistula plug in Crohn's disease patients with fistula-in-ano: a systematic review. Colorectal Dis. Apr 2016;18(4):351-356. PMID 26749385.

6. Xu Y, Tang W. Comparison of an anal fistula plug and mucosa advancement flap for complex anal fistulas: a meta-analysis. ANZ J Surg. Dec 2016;86(12):978-982. PMID 27680894.

7. Cirocchi R, Trastulli S, Morelli U, et al. The treatment of anal fistulas with biologically derived products: is innovation better than conventional surgical treatment? An update. Tech Coloproctol. Jun 2013;17(3):259-273. PMID 23207714.

8. van Koperen PJ, Bemelman WA, Gerhards MF, et al. The anal fistula plug treatment compared with the mucosal advancement flap for cryptoglandular high transsphincteric perianal fistula: a double-blinded multicenter randomized trial. Dis Colon Rectum. Apr 2011;54(4):387-393. PMID 21383557.

9. Ortiz H, Marzo J, Ciga MA, et al. Randomized clinical trial of anal fistula plug versus endorectal advancement flap for the treatment of high cryptoglandular fistula in ano. Br J Surg. Jun 2009;96(6):608-612. PMID 19402190.

10. Pu YW, Xing CG, Khan I, et al. Fistula plug versus conventional surgical treatment for anal fistulas. A system review and meta-analysis. Saudi Med J. Sep 2012;33(9):962-966. PMID 22964807.

11. Leng Q, Jin HY. Anal fistula plug vs mucosa advancement flap in complex fistula-in-ano: A meta-analysis. World J Gastrointest Surg. Nov 27 2012;4(11):256-261. PMID 23494149.

12. O'Riordan JM, Datta I, Johnston C, et al. A systematic review of the anal fistula plug for patients with Crohn's and non-Crohn's related fistula-in-ano. Dis Colon Rectum. Mar 2012;55(3):351-358. PMID 22469804.

13. Garg P, Song J, Bhatia A, et al. The efficacy of anal fistula plug in fistula-in-ano: a systematic review. Colorectal Dis. Oct 2010;12(10):965-970. PMID 19438881.

14. Jacob TJ, Perakath B, Keighley MR. Surgical intervention for anorectal fistula. Cochrane Database Syst Rev. May 12 2010(5):CD006319. PMID 20464741.

15. Senejoux A, Siproudhis L, Abramowitz L, et al. Fistula plug in fistulising ano-perineal Crohn's disease: a randomised controlled trial. J Crohns Colitis. Feb 2016;10(2):141-148. PMID 26351393.

16. Hall JF, Bordeianou L, Hyman N, et al. Outcomes after operations for anal fistula: results of a prospective, multicenter, regional study. Dis Colon Rectum. Nov 2014;57(11):1304-1308. PMID 25285698.

17. Hyman N, O'Brien S, Osler T. Outcomes after fistulotomy: results of a prospective, multicenter regional study. Dis Colon Rectum. Dec 2009;52(12):2022-2027. PMID 19934925.

18. Fisher OM, Raptis DA, Vetter D, et al. An outcome and cost analysis of anal fistula plug insertion vs endorectal advancement flap for complex anal fistulae. Colorectal Dis. Jul 2015;17(7):619-626. PMID 25641401.

19. Christoforidis D, Pieh MC, Madoff RD, et al. Treatment of transsphincteric anal fistulas by endorectal advancement flap or collagen fistula plug: a comparative study. Dis Colon Rectum. Jan 2009;52(1):18-22. PMID 19273951.

20. Wang JY, Garcia-Aguilar J, Sternberg JA, et al. Treatment of transsphincteric anal fistulas: are fistula plugs an acceptable alternative? Dis Colon Rectum. Apr 2009;52(4):692-697. PMID 19404076.

21. Chung W, Kazemi P, Ko D, et al. Anal fistula plug and fibrin glue versus conventional treatment in repair of complex anal fistulas. Am J Surg. May 2009;197(5):604-608. PMID 19393353.

22. Vogel JD, Johnson EK, Morris AM, et al. Clinical practice guideline for the management of anorectal abscess, fistula-in-ano, and rectovaginal fistula. Dis Colon Rectum. Dec 2016;59(12):1117-1133. PMID 27824697.

23. National Institute for Health and Care Excellence (NICE). Bioprosthetic plug insertion for anal fistual. Sep 2019. https://www.nice.org.uk/guidance/ipg662. Accessed October 7, 2019.

Codes:
(The list of codes is not intended to be all-inclusive and is included below for informational purposes only. Inclusion or exclusion of a procedure, diagnosis, drug or device code(s) does not constitute or imply authorization, certification, approval, offer of coverage or guarantee of payment.)

CPT*

46707