**2.3 Anal fistula laser closure (FiLaC™)**

Fistula laser closure was first introduced in 2011 by Wilhelm. The procedure involves destruction of fistula tract using radial emitting laser probe by applying energy while retracting laser probe that was inserted through perianal opening [16]. It was proposed initially to close the site of internal opening with anorectal flap, but procedure was later modified by Giamundo to exclude any form of internal opening closure by using the shrinking effect of laser energy to obliterate the opening, as well as remaining fistula tract [17]. It is postulated that this approach has an advantage over simple diathermy because diathermy cannot elicit shrinking effect on surrounding tissues, and it is more difficult to regulate thermal damage on anal sphincter complex [18].

Since the technique introduction, multiple observational studies were reported and published but only one systematic review and meta-analysis currently exists (Elfeki et al). Overall, mean rate of primary healing among the analyzed studies was 67,3% which was increased to 69.7% with a repeated procedure. Only 5,5% of patients had complications, but those were all minor, scoring I or II on Clavien-Dindo scale. Weighted mean rate of fecal incontinence was 1% but was not statistically significant [19].

Drawback of this procedure is argued to be lack of visualization of fistula tract. Even though energy of the probe can be adjusted to different power settings, and therefore different depth of tissue penetration, there is still an issue of branching tracts that cannot be adequately accessed by blind insertion. On the other hand, increasing power of the laser diode in order to widely affect perianal tissue, could result in inadvertent damage of anal sphincter complex.

As the probe itself is a flexible instrument, it could potentially reach parts of fistula tract that are otherwise inaccessible behind the sharp angle such is often the case in suprasphincteric fistulas.

### **2.4 Rectal advancement flap (RAF)**

This is the oldest sphincter preserving technique, primarily reserved for treatment of complex anal fistulas. It was first described by Elting in the beginning of the 20th century but was implemented in everyday practice during the last few decades [20]. Many publications about the technique can be found under different names, such as endorectal, endoanal, transanal advancement flap etc.

First step in this procedure is to identify and excise internal fistula opening. Then the U-shaped or rhomboid flap with wider base side should be performed by dissecting anorectal mucosa and adjacent internal anal sphincter muscle. Curettage and irrigation of the whole of fistula tract should be performed followed by suture of defect in sphincter complex left by earlier fistula tract. Site is then covered by previously prepared flap and sutured (**Figure 4**).

Much research has been made about optimal flap thickness, whether be it only mucosal flap or full thickness flap which involves full transection of the rectal wall. Researchers found that there was statistically higher rate of primary healing in group with thicker flaps, but also noticed that there was higher rate of postoperative mild continence disturbance which was more severe the thicker flap was [21–23]. Another frequently discussed issue was necessity to use loose seton prior flap operation to rase the rate of primary healing. Even though there have not been clear statistical findings, many surgeons advocate seton placement as an important step

**Figure 4.** *Mobilized full-thickness rectal advancement flap.*

before flap operation [24]. Factors that could affect healing after flap procedure are obesity and smoking, so patients should be advised to quit smoking and to try to reduce their weight prior flap operation [25–27].

There have been many publications and several systematic reviews and meta-analyses on this technique where the effectiveness was shown to be 60–80%, but same cases also reported some degree of postoperative fecal disturbance [23, 28, 29]. That is why we cannot talk about pure sphincter preserving technique, even though this technique was developed primarily for treatment of complex high anal fistulas that would otherwise have high postoperative risk of fecal disturbance if treated by lay open techniques.

It is important to note that although RAF is a treatment technique, it is used by itself as a method of internal fistula opening closure when preforming other sphincter preserving procedures. This type of internal opening closure can be made in all cases, but is most appropriate when large openings are present, and when tension on the suture line is presumed to be increased by simple mattress suturing. RAF is also technically most demanding to preform, because it involves dissection and suturing in a confined space, often deeply in anal canal. Flap itself has to be rhomboid in shape or U-shaped with wider base, so that circulation is adequate to avoid dehiscence or flap ischemia. Excessive grasping should also be avoided as well as too big a strain on the suture line.

#### **2.5 Autologous platelet rich plasma (APRP)**

Although autologous platelet rich plasma (APRP) is used as treatment in other fields of medicine, such as plastic surgery, orthopedics, and dental medicine, treatment of anal fistula using this technique has emerged in the last decade.

Autologous platelet-rich plasma (APRP) is platelet concentration derived from centrifuged full blood after removal of red blood cells. Such plasma is a rich source of growth factors implicated in tissue healing and regeneration [30, 31].

Treatment itself consists of removal of granulation tissue lining the fistula tract followed by irrigation and closure of the internal opening. APRP injection, which

*Sphincter Preserving Techniques in Anal Fistula Treatment DOI: http://dx.doi.org/10.5772/intechopen.99547*

was previously prepared using gravitational platelet separation procedure from autologous blood sample, is then injected into the fistula tract [32]. Specifics of the separation procedure are beyond the scope of this chapter. Majority of publications combined mucosal advancement flap with APRP injection [33–36].

There have been several publications with the reported average healing rate from 60 to 90% [34–36]. All of publications had relatively small number of patients enrolled and still no meta-analyses exist on the subject. No continence disturbances were reported.

This is still somewhat experimental procedure and not widely used. Platelet separation procedures require specialized equipment that is often only available in larger institutions. Cost per patient also exceeds that of the other techniques, which is why this technique needs more solid evidence for patient benefit before it can be considered to become one of the mainstream sphincter preserving treatments.

#### **2.6 Hybrid sphincter preserving techniques**

Hybrid sphincter preserving techniques combine two techniques into a single procedure. Some of the reported combinations are as follows.

LIFT-VAAFT is used with intention of combining internal fistula opening closure in the intersphincteric plane with VAAFT to destroy remaining fistula tract and to check for any branching tracts [37]. A new and yet unpublished report combines VAAFT and FiLaC procedures with the same fundamental philosophy [38]. VAAFT was also combined with RAF in order to close especially large internal openings that would not be suitable for closure with mattress suture [10].

BioLIFT combines LIFT with insertion of bioprosthetic graft in the intersphincteric plane. On a study of 31 patients, success rate was reported to be 94% in a one-year follow-up period [39]. Another study combined LIFT and human acellular dermal matrix as a bioprosthetic plug with reported success rate of 95% on 21-patient sample [40].

Advancement flap was combined with injection of porcine dermal collagen implant through external opening in a study of 24 patients with success rate of 82,5% in a 14-month follow-up period [41].

It was to be expected that surgeons, encouraged by initial promising results, started combining sphincter preserving techniques in order to achieve even better healing rates. Some of these procedures were more successful than others, but majority of reports are on a single institution basis or case reports and relatively few patients. Idea of combining two (or more) techniques in order to recruit the individual one's advantage is sound. For example LIFT combined with VAAFT has potential to resolve pathology in intersphincteric plane as well as find additional tract branches. VAAFT in conjunction with FiLaC can visualize branching tracts while managing to reach fistula behind sharp angle etc.

For now, as there is no evidence to the contrary, we can use hybrid techniques in order to take advantage of one's strong suits, overcome the shortages of another and vice versa. Until evidence is found that one technique, or combination of techniques, has significantly better results over the others, they should be tailored individually depending on patient's case.

#### **3. Discussion and conclusions**

Complex anal fistulas present a complex problem, although they are often not perceived as such. Operation of anal fistula is usually one of the first operations that a surgical resident will do in the course of their residency as it is thought as simple and straightforward procedure. The actuality is that unless patient requires only

seton placement, no treatment of complex fistulas should be made if surgeon is not acquainted with sphincter preserving procedures or knows how to repair anal sphincter if treatment using traditional techniques results in fecal incontinence. The most difficult cases should be treated in high-volume institutions only, as successfully treated fistula resulting in any degree of fecal incontinence is not a good outcome.

Important point in every operation is to try to identify internal opening even when one is not evident. This is especially important in very complex cases, such as horseshoe fistulas, when multiple internal openings might be present but not all of them immediately visible. Goodsall's rule is a good waypoint as to where the opening might be. Failure of dealing with internal opening is almost certain to result in procedure failure. Surgeon should take care not to use excessive force when identifying the opening to avoid creation of false openings or false tracts. Easy way to find the opening is to inject hydrogen peroxide through external opening and look for the spurt of foam in the anal canal.

Several things can be considered to increase the chance of healing, especially when preforming RAF. It might be a good idea to try to reduce intraoperative fecal matter and postoperative stool passage through the anal canal by applying enema. Postoperatively stool regulation by avoiding hard stool and excessive straining should be advised. Although not specific to this pathology, flavonoid use after hemorrhoidectomy has been observed to reduce inflammatory reaction and pain by reducing leukocyte adherence, so the same can be considered after these types of procedures [42].

There is also the issue of direct repair of fistula or seton placement in the first act. It is observed that seton placed and held for several weeks or months helps draining perianal sepsis and promotes fibrosis of the tract, making the subsequent sphincter preserving procedure easier. Therefore, an effort should be made to decrease perianal inflammation before attempting definite procedure, if possible. This opinion is not uniform between surgeons however. Other opinion is that the incidence of false tracts creation with metal probes while placing setons is unacceptably high, so that in this case, the wrong tract ends up being treated and reccurence is certain. This kind of belief is mostly anecdotal and there is no evidence in scientific literature.

Many new methods of sphincter preserving techniques for treating anal fistula emerged in the last 10–15 years. The shear fact that so many different procedures are proposed, shows that there is no best technique, and those that initially showed exceptional results usually could not be replicated in another institution. This speaks volumes about the complexity of anal fistula problem for the colorectal surgeon and hints that there is much that we still do not understand.

Nevertheless, several techniques gained somewhat wider acceptance, such as LIFT, VAAFT and RAF. Problem in choosing the best procedure lies in heterogeneity of fistulas and still no algorithm exists to rely on, so it is actually no surprise that a wide variety of procedures exist in the first place. We have tried to summarize characteristics of aforementioned techniques along with proposed indications and their pros and cons, but ultimately decision on what technique to choose should still be made on individual basis, surgeon's preference and on equipment availability.

Still, more randomized studies are needed. It is to be expected that success rate of these procedures will increase somewhat as the time passes given that a lot of publications reported initial results that are burdened by surgeon's learning curve. With increasing amount of sphincter preserving procedures being underwent, we will probably have more results to rely on in the future and to extrapolate better conclusions.

## **Conflict of interest**

The authors declare no conflict of interest.

*Sphincter Preserving Techniques in Anal Fistula Treatment DOI: http://dx.doi.org/10.5772/intechopen.99547*
