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| EXPERT COMMENTARY |
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| Year : 2019 | Volume
: 2
| Issue : 3 | Page : 88-93 |
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The science, techniques, and art of anal fistula treatment
Arshad Ahmad
Department of Surgery, King George's Medical University, Lucknow, Uttar Pradesh, India
| Date of Submission | 10-Jul-2020 |
| Date of Decision | 19-Jul-2020 |
| Date of Acceptance | 14-Aug-2020 |
| Date of Web Publication | 22-Sep-2020 |
Correspondence Address:
Dr. Arshad Ahmad
Department of Surgery, King George's Medical University, Lucknow, Uttar Pradesh
India
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/IJCS.IJCS_21_20
Anal fistula is a diverse disease. There is no single treatment which is effective for all types of anal fistulas. The management of simple anal fistula is straightforward, and a fistulotomy is recommended. However, in complex anal fistula if fistulotomy or fistulectomy is performed, it is combined with primary sphincter repair. Alternatively, a sphincter sparing procedure may be performed for complex anal fistula. The basic principle of sphincter preserving surgery for anal fistula involves three basic steps: disconnection of the tract from the anal canal, deepithelialization of the tract, and drainage from the external opening. The disconnection of the fistula tract from the anal canal can be achieved by direct closure of the internal opening, with endoanal advancement flap or with ligation of intersphincteric fistula tract procedure. After disconnecting the fistula from the anal canal, the remaining tract, which is now converted into a sinus is cleaned and deepithelialized. The tract is deepithelialized either mechanically by curetting or by using an energy source-like LASER or endocautery. The external opening of the tract is widened so that it does not close and continues to drain until the fistula is completely healed. The art of anal fistula treatment involves the assessment of the extent of the disease and selecting appropriate treatment strategy for a particular patient. None of the procedures are technically very demanding; however, selecting the right procedure for a particular patient is important.
Keywords: Anal fistula, fistula laser closure, fistulotomy, ligation of intersphincteric fistula tract, video-assisted anal fistula treatment
How to cite this article:
Ahmad A. The science, techniques, and art of anal fistula treatment. Indian J Colo-Rectal Surg 2019;2:88-93 |
| Introduction | |  |
Anal fistula is a diverse disease. The spectrum of the disease ranges from a very simple intersphincteric fistula, requiring a small surgical procedure for the long-term cure to a very complex suprasphincteric fistula which often needs multiple surgeries. In most cases, anal fistula is of cryptoglandular origin and represents the chronic form of a cryptoglandular abscess.[1] Infection of the anal gland leads to the development of submucosal or intersphincteric abscess depending on the location of the gland. A submucosal abscess usually resolves or drains spontaneously into the anal canal through the primary opening of the anal gland. However, an intersphincteric abscess usually grows further and can extend to perianal, ischiorectal or rarely to supralevator spaces. This results into the development of perianal, ischiorectal, or supralevator abscess. Spontaneous or surgical drainage of the abscess results into the development of intersphincteric, transsphincteric, or suprasphincteric fistula, respectively. The internal or primary opening of the cryptoglandular anal fistula is always present in the crypt at the pectinate line. An extrasphincteric fistula where the internal opening is above the pectinate line is usually secondary in nature. This is either created iatrogenically or is the result of Crohn's disease, tuberculosis, or descending pelvic infection. The detailed classification of the anal fistula is beyond the scope of this article.
There is no single treatment which is effective for all types of anal fistulas. However, there is a consensus about the treatment of simple anal fistula where a fistulotomy is recommended. A fistulotomy divides the sphincters and completely exposes the disease. Healing rates for fistulotomy can be very good for subcutaneous and intersphincteric fistulas, but the risk of incontinence rises with the amount of external sphincter muscle that has been divided.[2] Therefore, in complex anal fistula, fistulotomy or fistulectomy may be combined with primary sphincter reconstruction. For fistulectomy with primary sphincter reconstruction as a cutting procedure, promising results, in a small number of publications, were found especially for patients with preexisting incontinence due to former therapies,[3],[4],[5]
Alternatively, a sphincter sparing procedure may be performed for complex anal fistula. There are many sphincter preserving procedures available and new procedures continue to evolve. All the sphincter sparing procedures are associated with considerable rate of recurrence. When a sphincter sparing procedure is performed, the sphincters are not divided, and hence, the entire disease is not exposed. There is a chance that some focus of the disease is left unattended and that becomes a source of recurrence.
The understanding of the components of anal fistula and selecting appropriate procedure is important for effective treatment. An anal fistula has three components, a primary or internal opening, a secondary or external opening, and an epithelialized tract between the two openings. When a fistulotomy is performed, all three components are laid open. However, when a sphincter preserving procedure is performed, each component needs to be addressed. Often, there are secondary extensions from the primary tract or occult abscesses within the tracts. When a fistulotomy is performed, the secondary extensions or the abscesses are simultaneously drained. However, when a sphincter sparing procedure is performed, these secondary extensions or occult abscesses may not be drained and can cause recurrence. The treatment planning should begin with the assessment of extensions of the fistula tract and its relationship with the sphincter complex.
| The Science of Anal Fistula Treatment | | |
The ideal treatment of anal fistula is to completely expose and eradicate the tract and openings by doing a fistulotomy or fistulectomy. However, this is achieved at the expense of dividing the sphincters. This is suitable for simple anal fistula where only lower part of external sphincters (subcutaneous and superficial) and internal sphincter is involved. Division of this part of sphincters does not lead to any significant compromise in continence. Hence for the simple anal fistula, a fistulotomy is considered to be the gold standard treatment. Healing rates for fistulotomy can be very good[6],[7] for subcutaneous and intersphincteric fistulas. However, incontinence rates between 27% and 64% have been found for the fistulotomy procedure for complex anal fistulas.[8]
A complex fistula is one where the tract crosses the deep part of external sphincters or puborectalis. Division of this part of the sphincter muscles can lead to significant issues with the continence. If a sphincter cutting procedure (fistulotomy/fistulectomy) is performed for this type of anal fistula, it should be combined with a primary repair of the sphincter muscles. In a study of fistulectomy with primary sphincter reconstruction, the fistulas healed in 88% of patients with a recurrence rate of 10% and no case of high-grade incontinence after the surgical procedure.[9]
The other option for the treatment of complex anal fistula is to perform a sphincter preserving procedure. This means the treatment of anal fistula without division of sphincter muscles. The basic principle of sphincter preserving surgery for anal fistula involves three basic steps; disconnection of the tract from the anal canal, deepithelialization of the tract and drainage from the external opening.
| Disconnection of the Tract | | |
The disconnection of the fistula tract from the anal canal converts it into a blind sinus. It stops the persistent infection from reaching into the fistula tract from the anal canal. This is the most crucial step in the management of complex anal fistula. Various surgical procedures are available to accomplish this step. The disconnection of the fistula tract from the anal canal can be achieved by either closing the internal opening or by dividing and ligating the tract close to the anal canal (in the submucosal or intersphincteric plane). Once the tract is disconnected from the anal canal, persistent contamination of the tract stops. Failure of this step is the most common cause of persistent or recurrent fistula after a sphincter sparing procedure.
| Deepithelialization of the Tract | | |
After disconnecting the fistula from the anal canal, the remaining tract, which is now converted into a sinus, is cleaned and deepithelialized. The entire tract is cleaned and all the debris and infected tissue is removed. The tract is then deepithelialized to allow healing and obliteration by fibrosis. There is a chance that deepithelialization of the tract can lead to spread of contained infection into the soft tissue of the gluteal region. However, this risk is small when the external opening is wide open to allow the residual infection to drain. The inflammation in the surrounding tissue will eventually lead to fibrosis which will further help obliterating the tract.
| Drainage | | |
The external opening of the fistula is kept open to allow drainage of the tract. The remaining debris and secretions can drain through the external opening thus allowing the tract to close by fibrosis. The external opening should remain open till the entire tract is healed and obliterated. Finally, the external opening also obliterates completing the process of healing.
| The Techniques of Anal Fistula Treatment | | |
The treatment of simple anal fistula is straight forward and fistulotomy involves laying open of the entire tract from internal opening to external opening. This is combined with trimming or marsupialization of the edges. Any secondary tracts or abscesses are drained simultaneously. When fistulectomy is performed for complex fistula, sphincter repair is performed by end to end approximation of the internal and external sphincters. However, to achieve the three basic steps of sphincter preserving surgery in complex anal fistula many techniques have been put forth.
| Techniques for Disconnection of the Tract | | |
The disconnection of the fistula tract from the anal canal can be achieved by closure of the internal opening. The internal opening of the fistula can be closed by direct suture closure or by stapled closure. Alternatively, endoanal advancement flap or dermal advancement flaps can also be used to close the internal opening. The endoanal advancement flap consists of debridement of the internal opening, and mobilization of a segment of proximal healthy anorectal mucosa, submucosa, and muscle to cover the site. Reports indicate healing in 66% to 87% after initial endoanal advancement flap for cryptoglandular fistula.[10] Although the sphincter is not divided during flap formation, internal sphincter fibres may be included in the flap and mild-to-moderate incontinence is reported in up to 35% of patients, with concomitant decreased resting and squeeze pressures on postoperative manometry.[11],[12]
Ligation of intersphincteric fistula tract (LIFT) procedure is also meant to disconnect the fistula from the anal canal. This technique involves disconnection of the internal opening from the fistula tract at the level of the intersphincteric plane, without dividing any part of the anal sphincter complex. A meta-analyses of published data report that the LIFT procedure have resulted in fistula healing in 61% to 94% of patients, with little morbidity, and only rare alterations in fecal continence.[13],[14],[15],[16],[17] A recent meta-analysis of 24 original articles showed that 76.5% mean success rate, no incontinence, and 5.5% postoperative complication rate.[13] Submucosal ligation of the fistula tract is a similar procedure where the tract is ligated and divided in the submucosal plane.[18] Mushaya et al. has a prospective randomized design, in which a group of 25 patients underwent LIFT and 14 advancement flap. At 19 month of follow-up, the recurrence rate was 7% in the advancement flap group and 8% in the LIFT group, the only patient with postoperative minor incontinence belonged to the advancement flap group.[19]
The experience with plugs and glue has not been very satisfactory. The literature reports a success rate ranging from 24% to 88% with a mean follow-up of 8 months with fistula plugs.[20] Early results with glue were encouraging, but further data showed a very wide range of success from as low as 14% to as high as 74%.[21],[22]
| Techniques for Deepithelialization of the Fistula Tract | | |
The tract is deepithelialized either mechanically or by using an energy source. This is mechanically done by a curette. Video-assisted anal fistula treatment (VAAFT) is utilized to clean the tract using an endobrush. During the operative phase of VAAFT, the fistula wall is cauterized and all wasted material is eliminated along with closure of internal opening. In the study by Meinero and Mori, an overall success rate of 73.5% was achieved in 136 patients with non-Crohn' disease-related anal fistulae, within 2–3 months of follow-up. No postoperative incontinence or its worsening was reported.[23] In a systematic review and meta-analysis of the efficacy and safety of VAAFT (eleven studies, 788 patients), recurrence occurred in 14.2% patients after a median follow-up of 9 months. Recurrence rates varied according to the method of closure of internal opening from 15.3% after using staplers, 17.7% after suturing, to 25% after advancement flap. The weighted mean recurrence rate across the studies was 17.7%. The weighted mean complication rate was 4.8%.[24]
Fistula laser closure (FiLaC) is a novel sphincter-saving technique that uses an emitting laser probe, which destroys the fistula epithelium and simultaneously obliterates the remaining fistula tract. Since the main reason for surgical failure is a persistent fistula tract or remnants of fistula epithelium which were not excised, it was postulated that the benefit of the radial-emitting laser probe was to eliminate fistula epithelium or any granulation tissue in a circular manner and then, to obliterate the fistula tract by a shrinkage effect. Giamundo et al. performed FiLaC procedure on 35 patients with cryptoglandular and Crohn's disease-related fistulae. The procedure also included the closure of the internal opening by means of an anorectal flap. The overall success rate was 71% at 20 months of follow-up. They did not report any impairment of continence, but postoperative pain and anismus in 8 patients.[25] Oztürk andGülcü reported a success rate of 82% at 12 months of follow-up, on 50 patients treated for intersphincteric and transsphinteric fistulas.[26]
| Drainage | | |
The external opening of the tract is widened so that it does not close and continues to drain until the fistula is completely healed. This can be surgically achieved by excising some tissue at the external opening. If there are multiple external openings, similar procedure is performed at all sites.
| The Art of Anal Fistula Treatment | | |
The art of anal fistula treatment involves the assessment of the extent of the disease and selecting appropriate treatment strategy for a particular patient. For recurrent fistula, a thorough history of incontinence should be taken and documented as previous surgeries may have caused some incontinence.
The first step in the management of anal fistula is to map the extent of fistula and classify the disease. This is done by the clinical examination and if required imaging (magnetic resonance imaging [MRI]/ultrasonography) can be used. MRI fistulography is used to see the transverse and vertical extent of the fistula tract and its relationship with the sphincters. The purpose of evaluation is also to rule out secondary tracts and abscesses. MRI has a positive predictive value of 93%, a negative predictive value of 90% for anorectal abscess, and a sensitivity of over 90% for fistula-in-ano.[27] The presence of an occult abscess is often a cause for recurrence after sphincter-sparing procedures. All abscesses should be drained liberally before a sphincter-sparing procedure is planned. However, sometimes, a sphincter cutting procedure can be performed in presence of an abscess (abscess drainage and primary fistulotomy). When a simple fistula is encountered during incision and drainage of an anorectal abscess, fistulotomy may be performed as long as the anticipated benefits (healing) are estimated to outweigh the risks (incontinence).[28],[29],[30] A 2010 Cochrane Review included 6 trials, with 479 patients, and demonstrated that sphincter division (through fistulotomy or fistulectomy) at the time of incision and drainage was associated with a significant decrease in abscess recurrence, persistence of fistula or abscess, and the need for subsequent surgery (relative risk, 0.13; 95% confidence interval [CI], 0.07–0.24), but an increased, although statistically insignificant, incidence of continence disturbances at 1-year follow-up (relative risk, 3.06; 95% CI, 0.7–13.45).[31]
Examination under anesthesia should be performed meticulously as this gives the best opportunity to know the extent of the disease. A fistuloscope may be very helpful in the identification of internal opening and secondary tracts. Usefulness of intraoperative ultrasound cannot be overemphasized. However, this is not available at most places. The use of contrast should be avoided early as it may stain and make further examination difficult. Every effort should be made to find the internal opening as the success of any procedure depends on this. However, if the internal opening is not found despite all efforts, one should just clean, curette, deepithelialize the tracts and widen the external opening. In case of persistent or recurrent disease, a repeat assessment with MRI should be planned. Alternatively, an experienced surgeon may prefer to core the tract until its origin and repair the sphincters.
After classifying the fistula and finding the internal opening, the next step is to decide whether a sphincter cutting or sphincter sparing procedure will be suitable for this patient. If the fistula is simple, a sphincter cutting procedure can be performed with minimal risk of incontinence. Recent, prospective multicenter studies indicate that when fistulotomy is used for simple anal fistula, in properly selected patients, the risk of fecal incontinence is minimal or none.[32] Risk factors for postoperative anal sphincter dysfunction include preoperative incontinence, recurrent disease, female sex, complex fistulas, and prior fistula or anorectal surgery.[8],[33],[34]
For complex anal fistula, a sphincter preserving approach is a safe option. Alternatively, a sphincter cutting approach with primary sphincter repair can be considered depending upon the experience of the surgeon. This may be a reasonable approach in the presence of preexisting incontinence due to previous surgeries as sphincter reconstruction may improve patient's overall continence.
If a sphincter preserving approach is considered, the next step is to select the appropriate procedure to deal with each component of anal fistula, i.e., internal opening, tract, and external opening. The three components of the anal fistula are managed by disconnection of the tract from the anal canal, deepithelialization of the tract, and drainage at external opening.
In patients, where no previous surgery was performed, and there is no scarring, LIFT procedure is a good option (for disconnection of the tract) as the planes are well maintained. In patients with recurrent disease and with significant scarring over the intersphincteric groove, an endoanal advancement flap may be performed for this purpose. Primary closure of internal opening after debridement should be considered when flap cannot be raised. Plugs and glues have not proven to be of value for this purpose.
For deepithelialization of the tract video-assisted endo-cautery or radial laser fiber may be used if available. If these energy sources are not available, a mechanical curettage should be performed. Other options are partial coring and excision of tract and curettage of the remaining tract. All external openings should be made wide open for drainage.
Whenever, a complex fistula is encountered, the patient should be well informed about the various treatment options and their possible outcome. However, the clinician should advise the best possible option in a given scenario. There should be a high index of suspicion for secondary fistula in case of recurrent and complex disease. All specimens should be sent for histology.
Management of secondary anal fistula depends on its cause. Medical treatment with minimal surgical intervention is the mainstay of treatment in Crohn's disease and tuberculosis. An iatrogenically created high internal opening in a cryptoglandular fistula can be closed by primary suturing or endoanal advancement flap. It is important to find the original primary opening in these cases and treat the fistula as per its extent as described earlier.
A preoperative continence assessment and its documentation are necessary, especially in cases of recurrent and complex anal fistula. Preoperative counseling and informing the patient about the possible outcome is the essential part of the management. Examination of patients during follow-up visits should preferably be performed by the operating surgeon himself.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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