What is the glue embolization procedure?

Fibrin glue therapy has been used as a surgical adjuvant since 1915.1 Fibrin glue ablation (FGA) has been used as a muscle-sparing alternative to traditional fistulotomy since 1991. Previous reports identify highly variable success rates ranging from 0 to 100 percent. This broad range is likely related to the often small numbered, mixed fistula groups that have been previously reported. Fibrin glue ablation is an attractive first-line treatment because it preserves continence and does not compromise future surgical treatment. Although early reports identified excellent initial results, this was tempered by later reports in patients with longer-term results.

The three largest prospective studies with long-term data report mean follow-up intervals of 18 to 28 months. To date, there are no published reports with long-term success rates at a mean follow-up of greater than 28 months. These previous reports included mixed fistula types and etiologies, as well as treatment with both commercial and autologous fibrin glue, making them less useful for extrapolation to specific types of fistulas. To our knowledge, this is the first report that reviews the outcome in cryptoglandular transsphincteric specific fistulas uniformly treated with commercial fibrin glue.

What are the benefits of the glue embolization procedure?

This study was limited by its retrospective nature and the loss of patients to follow-up. The selection of transsphincteric-specific fistulas that were unrelated to Crohn’s disease and free of simultaneous flap advancement limited the size of the cohort but yielded much more specific data. Previously published reports have included all types of anal fistulas. This makes it difficult to meaningfully compare healing rates between reports.

Historically, intersphincteric fistulas have above-average success rates, whereas rectovaginal fistulas and Crohn’s-associated fistulas have below-average success rates, resulting in greater variability of reported success rates.11,13 Additionally, previous work often has looked at all cryptoglandular fistulas in general rather than specific types. To evaluate a more uniform cohort, we have focused on the most common of FGA indications: cryptoglandular transsphincteric fistulas in patients without Crohn’s disease. Swinscoe et al.16 in 2005 reviewed 15 original papers on fibrin glue treatment of fistula-in-ano, which reported an overall healing rate of 53 percent with a wide variation between studies (10–78 percent ).

Unfortunately, the technique of fibrin glue ablation is not standardized. The technique for debridement of the fistula tract is especially variable among individual surgeons. Reports vary from simple irrigation to fulguration and even laser ablation of the tract epithelium.4,13,15 Consequently, it is difficult to quantify the extent of fistula tract debridement. This differential technique likely accounts for some of the wide variation in success rates. We have described our method of preparing the fistula tract in detail. We do not represent it as novel or ideal but rather as our current technique. This will hopefully allow others to more meaningfully evaluate our data. Our 61 percent initial success rate is comparable to recent publications.8–13 These short-term results are relatively discouraging. Roughly, 40 percent fail in the immediate perioperative period with an additional 10 percent of apparent early successes failing before the sixth month. It seems that if failure is to occur, it will do so during the initial six months postoperatively. Recurrence after the six-month interval seems to be an uncommon event.

Patients with cryptoglandular transsphincteric fistulas who are successful through six months seem to have durable long-term healing. Cintron et al.11 had previously found that recurrence after one year of closure was unlikely in a group of mixed etiology fistulas. Previous reports of later recurrences (4–6 percent) exist; however, the type of fistula and variety of fibrin glue used for these patients was not designated.11,13 Previous reports of FGA-associated abscesses range from 2 to 5 percent. Earlier reports have advocated both antibiotic irrigation to sterilize the tract or routine preoperative seton placement. It is unclear whether this would have improved the overall success rate or diminished the incidence of tract abscess in our cohort.13,14 Most previously reported series do not close or constrain the secondary os in any fashion to prevent premature extrusion of the fibrin plug. We have now discontinued the practice of suturing the secondary os closed after FGA.

What does the literature say about glue embolization procedure?

A retrospective chart review identified 36 patients with cryptoglandular transsphincteric anal fistulas all treated with commercially available Tisseel VH® (Baxter, Deerfield, IL) fibrin glue ablation surgery from May 2000 through March 2005. Exclusion criteria included previous fistula surgery, Crohn’s disease-related fistulas, and concomitant flap advancement procedure. All FGA were performed by colorectal surgeons at St. Vincent or Hamot Medical Center, Erie, Pennsylvania, from May 2000 through March 2005. Mechanical bowel preparation was uniformly used. Neither oral nor parenteral antibiotics were used. All patients underwent FGA after irrigation and debridement of the fistula tract under monitored anesthesia care.

Hydrogen peroxide was routinely irrigated followed by mechanical debridement with tapered surgical gauze in flossing back and forth fashion. Preoperative setons were not used. Fistuloscopy was not performed. Neither preoperative nor postoperative antibiotics were used. The 5 ml volume preparation of fibrin glue was routinely used to ensure that there was an excess of glue available for complete filling of the tract. Fibrin glue was always injected from the secondary os to the primary os. The excess extruded glue from the internal os was sharply amputated with a minimum of manipulation after allowing a minimum of three full minutes for congealing to avoid dislodgement of the fibrin plug.

The primary internal os was closed with absorbable sutures and without advancement flaps in all cases. Patients with fistulas considered by the surgeon to be of a large caliber and therefore potentially at greater risk of failure from early dislodgement of the fibrin glue plug underwent suture closure of the secondary os. Postoperative recommendations included a full liquid diet for the first 72 hours followed by the resumption of a high-fiber, well-hydrated diet. Patients were instructed to avoid tub and whirlpool baths for 72 hours. Showering was not restricted but avoidance of excess cleansing was advocated. Rectal suppositories, enemas, and temperatures were prohibited for two weeks. Vigorous activity and exercise were restricted for two weeks. The follow-up interval was calculated based on the time until fistula recurrence or the time of the last fistula-free evaluation. Patient follow-up was obtained by both telephone interview and office examination. Failure within six weeks was considered an immediate failure. Fistula closure beyond six weeks postoperatively was considered an initial success.

How does glue embolization work?

The Venablock System includes 3 ml of polymer-based cyanoacrylate and a delivery system. The GSV is accessed percutaneously with a micropuncture introducer kit, followed by insertion of a 0.035 in. J guidewire. The lowest insufficient point of the vein was selected for the entry. The 5F introducer sheath was advanced over J guidewire to the SJF under ultrasound control. The cyanoacrylate is extracted with a 3 ml syringe, which is then attached to the 4F delivery catheter and injection gun. This catheter has a hydrophobic design to help prevent cyanoacrylate-mediated adhesion to the vein wall and has a specific configuration to enhance sonographic visibility. The catheter is filled with cyanoacrylate except for the final 3 cm segment. The delivery catheter is inserted into the introducer sheath and secured with a spinlock mechanism. Using direct visualization with a standard linear ultrasound probe in the long axis, 3 cm of the 4F catheter tip is exteriorized from the 5F introducer sheath and positioned 3 cm distal to the SJF.