Abstract and Background
Abstract
Background: Low transsphincteric fistulas less than 1/3 of the sphincter complex are easy to treat by fistulotomy with a high success rate. High transsphincteric fistulas remain a surgical challenge. Various surgical procedures are available, but recurrence rates of these techniques are disappointingly high. The mucosal flap advancement is considered the gold standard for the treatment of high perianal fistula of cryptoglandular origin by most colorectal surgeons. In the literature a recurrence rate between 0 and 63% is reported for the mucosal flap advancement. Recently Armstrong and colleagues reported on a new biologic anal fistula plug, a bioabsorbable xenograft made of lyophilized porcine intestinal submucosa. Their prospective series of 15 patients with high perianal fistula treated with the anal fistula plug showed promising results.
The anal fistula plug trial is designed to compare the anal fistula plug with the mucosal flap advancement in the treatment of high perianal fistula in terms of success rate, continence, postoperative pain, and quality of life.
Methods/Design: The PLUG trial is a randomized controlled multicenter trial. Sixty patients with high perianal fistulas of cryptoglandular origin will be randomized to either the fistula plug or the mucosal advancement flap. Study parameters will be anorectal fistula closure-rate, continence, post-operative pain, and quality of life. Patients will be followed-up at two weeks, four weeks, and 16 weeks. At the final follow-up closure rate is determined by clinical examination by a surgeon blinded for the intervention.
Discussion: Before broadly implementing the anal fistula plug results of randomized trials using the plug should be awaited. This randomized controlled trial comparing the anal fistula plug and the mucosal advancement flap should provide evidence regarding the effectiveness of the anal fistula plug in the treatment of high perianal fistulas.
Trial Registration: ISRCTN: 97376902
Background
A perianal fistula is a common condition. It has an incidence of 5.6 per 100.000 in women and 12.3 per 100.000 in men. The disease occurs predominantly in the third and fourth decade of life. It is believed that infection of the intersphincteric glands is the initiating event in fistula in ano, in a process known as the 'cryptoglandular hypothesis'.
Parks et al. developed a classification system in which fistula are divided into intersphincteric fistula, transsphincteric fistula, suprasphincteric fistula and extrasphincteric fistula. However the type of treatment depends not on the location of the fistula tract but of the level of the internal opening in the anal canal.
Low transsphincteric fistulas comprising less than 1/3 of the external sphincter complex are easy to treat by fistulotomy with a high success rate. High transsphincteric fistulas remain a surgical challenge. Surgical procedures include advancement flaps, loose-seton placement, and the installation of fibrin glue. All of these techniques have disappointing success rates. In the literature a recurrence rate between 0 and 63% is reported for the mucosal flap advancement. Recently, Van der Hagen et al. published the result of 41 patients with high transsphincteric, suprasphincteric and extrasphincteric fistula treated with a mucosal flap advancement. The success rate was a mere 37% (with a median follow-up of 72 months).
The fibrin glue is an alternative to the mucosal advancement flap, however long-term closure rates are low. The percentages being as low as 16 percent. The liquid consistency of fibrin glue is possibly not ideal for the purpose of closing anorectal fistulas, because the glue is easily extruded from the fistula tract by increased pressure.
Armstrong and colleagues reported a new biologic anal fistula plug. The plug is a FDA and CE approved bioabsorbable xenograft, made of lyophilized porcine intestinal submucosa by Cook Surgical, Inc., Bloomington, IN. The material has inherent resistance to infection, produces no foreign body or giant cell reaction, and becomes repopulated with host cell tissue during a period of three months. The material was fashioned into a conical plug and secured into the primary opening of the fistula tract. Armstrong achieved promising results in a prospective series of 15 patients treated with the anal fistula plug. They compared the results with ten patients using fibrin glue. Patients with high anorectal fistulas (high transsphincteric or deeper) were included. Excluded were patients with Crohn's disease or superficial fistulas (low transsphincteric or more superficial). At a median follow-up of 13.8 ±3.1 weeks they achieved a significant better fistula closure rate of 87% compared to the fibrin glue group (P <0.05).
These results call for a prospective randomised controlled trial. Since mucosal flap advancement is the preferred treatment for high cryptoglandular perianal fistula, the anal fistula plug will be compared with mucosal flap advancement in a randomised setting.