**8.2 Sphincter preservation or sphincter reconstruction procedures for both low and high fistula**

Surgeons generally try to avoid sphincter cutting techniques. Ligation of Intersphincteric Tract (LIFT) procedure avoids sphincter cutting, using a small incision to explore the intersphincteric space to ligate and excise the intersphincteric tract [4] or to drain intersphincteric abscess [29]. Additional procedure in combination with LIFT such as closure of internal opening, excision of external tract and bioprosthetic mesh have been reported to improve outcomes [32]. A recent report from the original birthplace of LIFT procedure reported 10 year overall primary healing rate of 87.65%, and overall healing rate after reoperation was 99.2%. True recurrences were due to recanalization as a result of incorrect identification of intersphincteric tract. However, majority of recurrences were due to infection in the intersphincteric wound, leading to intersphincteric fistula which was easily treated by fistulotomy [20]. Other reports cited Crohn's disease, complex multiple fistulas and horseshoe pattern as a common cause of recurrences [33], stressing the importance of identification of secondary tracts and abscesses. In the author's view, LIFT procedure is best combined with additional curettage, drainage or excision of external fistula tracts/abscess. Recently, the original author reported slight modification where LIFT incision was loosely approximated and tube drain inserted to reduce intersphincteric space infection and promote secondary healing [29]. A recent meta-analysis and systematic review reported overall pooled success rate of 76.5% and incontinence rate of 1.4% [21].

Excision of fistula with immediate sphincter reconstruction is an alternative to reduce the risk of incontinence, at the same time completely eradicate intersphincteric and secondary tracts. It is suitable for both low and high transphincteric fistula. Procedure is similar as described in 8.1, with additional sphincter repair to restore continuity. Term as Fistulotomy or fistulectomy with primary sphincteroplasty (FIPS), Ratto reports 93.2% overall success rate, with a low morbidity rate [33]. Overall postoperative worsening continence rate was 12.4% mainly post-defecation soiling, without significant changes in anorectal manometry parameters [33]. In general, this technique produces higher success rate compared to LIFT procedure, albeit variations of techniques and terms used across institutions [34]. Incontinence is still a major concern, despite being much lower than fistulotomy alone. It is recommended in the German's S3 guideline but not in other major guidelines [26]. In the author's recent experience, this procedure produces excellent outcome in both low and high transphincteric chronic fistula, and extrasphincteric secondary (branching) tracts can be excised or curetted concurrently. However, in acute abscess stage, initial seton drainage is preferred prior to FIPS to reduce the risk of breakdown of sphincter repair [34].

#### **8.3 Role of seton in complex fistula**

Loose draining seton allows initial control of sepsis prior to definitive surgery to improves success rate. German S3 guideline used the term fibrosing seton [26]. It allows drainage of abscess and forms a thick fibrous fistula tract, which can be dealt with easily on the next elective surgery. Draining seton before LIFT shows no added benefits [32]. However, seton before fistulotomy and sphincter reconstruction showed benefits in downstaging high transphincteric to low transphincteric type [34]. From personal experiences, seton drainage can also be utilized to drain ischioanal/Infralevator collections with multiple external openings after debridement or curettage to prevent extensive wounds in the perineum.

#### **8.4 Sphincter saving biomaterials and novel techniques**

Many sphincter saving biomaterials and novel techniques surfaced in the last 4 decades to deal with complex fistula with wide variation of success rates across continents. Among those are anal fistula plug [35, 36], fibrin glue [26], laser procedures [37], Video Assisted Anal Fistula Tract Treatment (VAAFT) [38] and endoscopic clips (OTSC) [39]. Across the board, none of these procedures have reported very high success rate. This is likely due to the fact that most procedures, in their attempt to avoid cutting sphincters, only focus on the closure of internal opening and/or the fistula tract, but do not eradicate the intersphincteric sepsis and its secondary tracts. The author's opinion is that these procedures are highly specialized and are often based on selected specialized institutions. Therefore, usage of these techniques should be reserved to experts of the respective fields.

#### **8.5 Approach for high intersphincteric fistula and extensions**

Garg described an improved procedure in 2017 for high fistulas termed Transanal Opening of the Intersphincteric Space (TROPIS) [30]. High intersphincteric tracts and abscesses are typically difficult to reach via intersphincteric approach or conventional probing from external opening, and usually branching. TROPIS procedure allows lay open and drainage of these tracts into the anal canal, thus eradicating septic nidus at the high intersphincteric plane, which is usually posterior and was termed as the posterior deep space in the

previous segment 4.5. This is done through the internal opening and external sphincter is not cut. The external branching tracts in the ischiorectal fossa were curetted. The space is left open for secondary healing. In the initial prospective cohort of 61 patients, success rate was 84.6% with no significant changes in continence score. The series consist of a mixture of high transphincteric type (anterior and posterior) and high intersphincteric type [30]. Incision on the internal


*CED: Short for closure of external sphincter defect. After lay open of intersphincteric tracts and abscesses, an attempt is made to close the defect where transphincteric tract traverses the external sphincter. This can be done transanally or via external opening wound.*

*Mod: Modification by loosely approximate incision with tube drains to allow drainage and secondary healing of intersphincteric wound [29].*

*Add: Additional procedures includes drainage of ischioanal/Infralevator abscess, curettage or excision of external tracts, insertion of drains to the ischiorectal space [15, 29, 30].*

*Seton: Use of loose draining seton for drainage, induce fibrosis to form thickened tract and allows downgrading of high to low transphincteric fistula [34].*

*NA: Not applicable.*

*\* Caution in performing FIPS in anterior transphincteric fistula, especially in female patients where external sphincter is thin, lack of support anteriorly and risk injuring perineal body.*

**Table 5.**

*Summary of appropriate surgical treatment for different types of fistula pattern based on the principles of surgical treatment. No single procedure is 100% successful, therefore our clinical judgment is important in deciding on additional procedures, combination, staged approaches or modification to achieve our goal.*

sphincter is shown to be safe without worsening incontinence [2, 30, 40]. In author's personal experience, TROPIS procedure is an excellent approach for high intersphincteric type and posterior high transphincteric type, especially if transphincteric fistula is located at the puborectalis level. However, like LIFT procedure, combination with drainage, curettage or excision of external tracts is necessary to reduce recurrences.

### **8.6 Deciding on the best surgical approach**

To achieve good outcomes for anal fistula surgery, the author concludes that; 1) Understanding of type and natural patterns of fistula is extremely important, 2) The 4 principles of surgical treatment should be adhered to as closely as possible, and 3) No one surgical technique is suitable for all types of fistula. Therefore, selecting the appropriate procedure is important and to our best knowledge, no guidelines or classifications so far outlines a complete treatment algorithm especially on complex fistulas. Based on this review of evidence and best clinical judgment of the author, **Table 5** below attempts to summarize reasonable treatment options available for different fistula types to guide surgeons, where combination of procedures, additional procedures or modification of procedures is preferred over single modality (refer to **Table 5**).
