Persistence of idiopathic anal fistula may be related to epithelialization

Clinicopathological determinants of recurrence after surgical treatment of fistula-in-ano in a Ghanaian teaching hospital

AIM

The aim of this work is to describe the clinicopathological and surgical aspects of fistula-in-ano and assess the risks associated with recurrence of the disease in a Ghanaian teaching hospital.

METHOD

This was a retrospective observational study assessing all fistula-in-ano surgeries performed at the Korle Bu Teaching hospital from January 2014 to January 2021 that had completed follow up of at least 3 months after wound healing. Demographic, clinical, pathological and surgical data were extracted from patient records. Logistic regression analysis was used to test for association between these variables and recurrence.

RESULTS

A total of 105 patients underwent 124 fistula surgeries. Their median age was 41 years, the male:female ratio was 4:1 and 12 had comorbidities including human immunodeficiency virus infection and diabetes mellitus. Thirty-one per cent (39/124) of fistulas had previously been operated on. At surgery, 51% (64/124) of fistulas followed a single straight tract, 30% (37/124) a single curved tract and 19% (23/124) had multiple curved tracts. More than half (65/124) were trans-sphincteric, 35% (44/124) suprasphincteric, 10% (12/124) subsphincteric and 2% (3/124) were intersphincteric. Sixty per cent of fistulas were treated with a ligation of intersphincteric fistula tract (74/124), 35% (44/124) a fistulectomy and 5% a fistulotomy. Recurrence after surgery was 22.5% (28/124); this was significantly higher for fistulas with multiple curved tracts (OR 4.153, 95% CI 1.431-12.054, p = 0.012) and fistulas with comorbidities (OR 3.222, 95% CI 1.076-9.647, p = 0.037).

CONCLUSION

There was high recurrence after fistula surgery with increased risk for fistulas with multiple tracts and the presence of comorbidities.

Human Amniotic Membrane for the Treatment of Cryptoglandular Anal Fistulas

Background: Implantation of the amniotic membrane and their derivatives can have a beneficial effect on tissue repair and regeneration. We report for the first time the implant of an amniotic membrane in a patient affected by cryptoglandular anal fistula. Methods: A patch of human amniotic membrane was implanted in a female patient affected by an anterior transphincteric fistula. Following an accurate curettage of the anal fistula, the cryopreserved amniotic membrane was thawed and then washed in the operating room; one side of the membrane was transfixed with a resorbable suture thus creating an implantable fusiform patch. The membrane was subsequently implanted into the fistula tract from the external to the internal opening. The inner and outer parts of the membrane were then sutured to the internal and external fistula openings. Results: No intraoperative or postoperative complications occurred. The patient was discharged one day after the procedure after an uneventful hospitalization. At the 1-week, 1- and 3-month follow-up visits no pain (VAS 0) was referred by the patient and no inflammation was evident at the level of the previous external fistula opening. Conclusions: The implant of human amniotic membrane in a patient affected by cryptoglandular anal fistula was safely and easily performed. Moreover, future studies to assess the efficacy in the long-term follow-up are needed.

Advanced Regenerative Medicine Strategies for Treatment of Perianal Fistula in Crohn's Disease

Regenerative medicine is an emerging therapeutic method that aims to reconstruct tissues and organs. This advanced therapeutic approach has demonstrated great potential in addressing the limitations of medical and surgical procedures for treating perineal fistula in patients with Crohn's disease. Recent developments in stem cell technology have led to a massive good manufacturing practices (GMPs) production of various stem cells, including mesenchymal and embryonic cells, along with induction of pluripotent stem cells to repair damaged tissues in the fistula. The recent advances in separation and purification of exosomes, as biologic nanovesicles carrying anti-inflammatory and regenerative agents, have made them powerful tools to treat this inflammatory disease. Further, tremendous advances in nanotechnology, biomaterials, and scaffold fabrication methods enable tissue engineering methods to synthesize tissue-like structures to assist surgical techniques. This review focuses on advanced regenerative-based methods including stem cell therapy, exosome therapy, and tissue engineering used in the treatment of perianal fistula. Relevant in vitro and in vivo studies and the latest innovations in implementation of regenerative medicine for this disease are also separately reviewed. Additionally, current challenges regarding implementation of g stem cells, exosomes, and tissue engineering methods for bridging the gaps between laboratory findings and clinic application will be discussed.

Seton in high anal fistula

The use of seton still remains a reasonably valid option for its simplicity and optimal results in treating high anal fistulae. Ours was a single-centre retrospective study on patients with supra-sphincteric and transsphincteric types of high anal fistula, using the 'kharsutra' as seton. The first group were treated with a seton alone, while the second with a seton and partial fistulotomy. Results were similar and quite acceptable in both groups.

Evaluation and management of perianal abscess and anal fistula: SICCR position statement

Perianal sepsis is a common condition ranging from acute abscess to chronic anal fistula. In most cases, the source is considered to be a non-specific cryptoglandular infection starting from the intersphincteric space. Surgery is the main treatment and several procedures have been developed, but the risks of recurrence and of impairment of continence still seem to be an unresolved issue. This statement reviews the pertinent literature and provides evidence-based recommendations to improve individualized management of patients.

Review article: pathogenesis of Crohn's perianal fistula-understanding factors impacting on success and failure of treatment strategies

BACKGROUND

Evidence from groups who have studied fistula aetiology and extrapolation from interventional studies supports a multifactorial hypothesis of Crohn's perianal fistula, with several pathophysiological elements that may contribute to fistula formation, persistence and resistance to treatment.

AIM

An evidence synthesis of current understanding of pathophysiological factors underlying Crohn's perianal fistula is presented, exploring the fundamental reasons why some treatments succeed and others fail, as a means of focussing clinical knowledge on improving treatment of Crohn's perianal fistula.

METHODS

Evidence to support this review was gathered via the Pubmed database. Studies discussing pathophysiological factors underpinning perianal fistula, particularly in Crohn's disease, were reviewed and cross-referenced for additional reports.

RESULTS

Pathophysiological factors that impact on success or failure of interventions for Crohn's perianal fistulae include the high-pressure zone, obliterating the dead space, disconnecting the track from the anus, removing epithelialisation, eradicating sepsis and by-products of bacterial colonisation, correcting abnormalities in wound repair and removing the pro-inflammatory environment which allows fistula persistence. Most current interventions for Crohn's perianal fistulae tend to focus on a single, or at best two, aspects of the pathophysiology of Crohn's anal fistulae; as a result, failure to heal fully is common.

CONCLUSIONS

For an intervention or combination of interventions to succeed, multiple factors must be addressed. We hypothesise that correct, timely and complete attention to all of these factors in a multimodal approach represents a new direction that may enable the creation of an effective treatment algorithm for Crohn's anal fistula.

Prognostic factors affecting outcomes in fistulating perianal Crohn's disease: a systematic review

BACKGROUND

One in three patients with Crohn's disease will develop a perianal fistulae, and one third of these will achieve long-term healing or closure. A barrier to conducting well-designed clinical trials for these patients is a lack of understanding of prognostic factors. This systematic review sets out to identify factors associated with prognosis of perianal Crohn's fistulae.

METHODS

This review was registered on the PROSPERO database (CRD42016050316) and conducted in line with PRISMA guidelines along a predefined protocol. English-language studies assessing baseline factors related to outcomes of fistulae treatment in adult patients were included. Searches were performed on MEDLINE and Embase databases. Screening of abstracts and full texts for eligibility was performed prior to extraction of data into predesigned forms. Bias was assessed using the QUIPS tool.

RESULTS

Searches identified 997 papers. Following removal of duplicates and secondary searches, 923 were screened for inclusion. Forty-seven papers were reviewed at full-text level and 13, 2 of which were randomised trials, were included in the final qualitative review. Two studies reported distribution of Crohn's disease as a prognostic factor for healing. Two studies found that CARD15 mutations decreased response of fistulae to antibiotics. Complexity of fistulae anatomy was implicated in prognosis by 4 studies.

CONCLUSIONS

This systematic review has identified potential prognostic markers, including genetic factors and disease behaviour. We cannot, however, draw robust conclusions from this heterogeneous group of studies; therefore, we recommend that a prospective cohort study of well-characterised patients with Crohn's perianal fistulae is undertaken.

Five years of experience with the FiLaC™ laser for fistula-in-ano management: long-term follow-up from a single institution

Background

There are limited data available concerning endofistular therapies for fistula-in-ano, with our group reporting the first preliminary outcomes of the use of the radial fibre Fistula laser Closing (FiLaC ™) device.

Methods

The aim of this study was to assess a cohort of anal fistulae managed with laser ablation plus definitive flap closure of the internal fistula opening over a long-term follow-up. Factors governing primary healing success and secondary healing success (i.e. success after one or two operations) were determined.

Results

The study analysed 117 patients over a median follow-up period of 25.4 months (range 6–60 months) with 13 patients (11.1%) having Crohn’s-related fistulae. No incontinence to solid and liquid stool was reported. Minor incontinence to mucus and gas was observed in two cases (1.7%), and a late abscess treated in one case (0.8%). The primary healing rate was 75/117 (64.1%) overall, and 63.5% for cryptoglandular fistulae versus 69.2% for Crohn’s fistulae, respectively. Of the 42 patients who failed FiLaC™ 31 underwent a second operation (“Re-FiLaC™”, fistulectomy with sphincter reconstruction or fistulotomy). The secondary healing rate, defined as healing of the fistula at the end of the study period, was 103/117 (88.0%) overall and 85.5% for cryptoglandular fistulae versus 92.3% for Crohn’s fistulae. A significantly higher primary success rate was observed for intersphincteric-type fistulae with primary and secondary outcome unaffected by age, gender, presence of Crohn’s disease, number of prior surgeries and the type of flap designed to close the internal fistula opening.

Conclusions

There is a moderate primary success rate using first-up FiLaC™ treatment. If FiLaC™ fails, secondary success with repeat FiLaC™ or other approaches was high. The minimally invasive FiLaC™ approach may therefore represent a sensible first-line treatment option for anal fistula repair.

Immunopathological characterization of cryptoglandular anal fistula: a pilot study investigating its pathogenesis

AIM

The pathogenesis of cryptoglandular anal fistula (AF) is still under debate. Tissue inflammation could play a primary role. The pathological process of epithelial mesenchymal transition (EMT) might be involved but has never been investigated.

METHOD

In a prospective pilot study, 12 patients with an AF had a fistulectomy. The excised track was divided into proximal (intrasphincteric) and distal (extrasphincteric) parts which were subjected to standard histopathological examination. The cytokines IL-8 and IL-1beta were analysed as markers of inflammation, while EMT was evaluated by expression of TGF-beta, Vimentin, Zeb-1, Snail and E-cadherin. The mRNA and protein expression of these molecules was investigated by real-time PCR (RT-PCR), Western blot analysis and immunohistochemistry and was compared with that of the normal adjacent tissue.

RESULTS

Chronic inflammation and granulation tissue and a stratified epithelium were evident on standard histopathological examination. The cytokine IL-8 was more expressed in the proximal than the distal part of the track (fold increase 4.34 vs 3.60), while the reverse was found for IL-1beta (fold increase 1.33 vs 2.01); both were more intensely expressed compared with the normal anal mucosa. EMT was demonstrated, in both proximal and distal parts of the track, with an increase of TGF-beta, Vimentin, Zeb-1 and Snail and a mean decrease of E-cadherin. Western blot analysis and immunohistochemistry confirmed the protein expression.

CONCLUSION

The study suggests that chronic inflammation is present in cryptoglandular fistulas. The inflammatory pattern might be different in the proximal than in the distal part of the fistula track. The cytokines IL-1beta and IL-8 could play a possible role in fistula formation. The study demonstrates for the first time the potential importance of EMT in the pathogenesis of cryptoglandular AF.

Fistula tract curettage and the use of biological dermal plugs improve high transsphincteric fistula healing in an animal model

PURPOSE

The treatment of high transsphincteric fistula is a complex procedure, which may be associated with the risk of recurrence and fecal incontinence. In this study, we used an animal model to compare different types of sphincter-preserving treatments for transsphincteric fistula.

METHODS

Sixteen female New Zealand rabbits, weighing 2.8-4.8 kg underwent a surgical creation of high transsphincteric fistula. After 6 weeks, magnetic resonance imaging (MRI) was performed in order to confirm fistula formation and measure the fistula diameter. The rabbits were divided into three groups. Group 1 received no plug treatment (control). Autologous dermal graft and acellular dermal matrix were used as a plug in groups 2 and 3, respectively. Five weeks after treatment, fistula tract healing was determined by measuring the largest fistula diameter with MRI. All rabbits were euthanized and the anorectum excised en bloc for histopathological examination.

RESULTS

According to the MRI findings, all groups showed significant healing after the treatment (p < 0.05). The healing rate of fistula diameters after treatment was 40, 66, and 29% in the control, dermal graft, and acellular dermal matrix groups, respectively. In terms of negative healing parameters such as neutrophil, eosinophil, lymphocyte, and plasmocyte accumulation, dermal graft and acellular dermal matrix groups showed significantly lower results than those in the control group (p < 0.05).

CONCLUSION

According to MRI and histopathological results, fistula tract curettage and fistula orifice closure improved transsphincteric anal fistula healing. Additionally, in this study, plug treatment favoring autologous dermal graft resulted in better healing.

Initial experience of treating anal fistula with the Surgisis anal fistula plug

BACKGROUND

Complex anal fistulas remain a challenge for the colorectal surgeon. The anal fistula plug has been developed as a simple treatment for fistula-in-ano. We present and evaluate our experience with the Surgisis anal fistula plug from two centres.

METHODS

Data were prospectively collected and analysed from consecutive patients undergoing insertion of a fistula plug between January 2007 and October 2009. Fistula plugs were inserted according to a standard protocol. Data collected included patient demographics, fistula characteristics and postoperative outcome.

RESULTS

Forty-four patients underwent insertion of 62 plugs (27 males, mean age 45.6 years), 25 of whom had prior fistula surgery. Mean follow-up was 10.5 months Twenty-two patients (50%) had successful healing following the insertion of plug with an overall success rate of 23 out of 62 plugs inserted (35%). Nineteen out of 29 patients healed following first-time plug placement, whereas repeated plug placement was successful in 3 out of 15 patients (20%; p = 0.0097). There was a statistically significant difference in the healing rate between patients who had one or less operations prior to plug insertion (i.e. simple fistulas) compared with patients who needed multiple operations (18 out of 24 patients vs. 4 out of 20 patients; p = 0.0007).

CONCLUSIONS

Success of treatment with the Surgisis anal fistula plug relies on the eradication of sepsis prior to plug placement. Plugs inserted into simple tracts have a higher success rate, and recurrent insertion of plugs following previous plug failure is less likely to be successful. We suggest the fistula plug should remain a first-line treatment for primary surgery and simple tracts.

New type of seton with irrigating tube for the treatment of high complex anal fistula: a simple and effective instrument

This study compared the clinical results of surgical treatment of high complex anal fistula with a conventional seton and a new type of seton consisting of an elastic sheath and alloy core tube for irrigation of the wound track. A total of 438 patients were included in the study; 215 were treated with a conventional seton and 223 with the new-type seton. In patients treated with the new-type seton, the wound track was irrigated daily with 100 ml physiological saline, 100 ml hypertonic saline and 0.5 g metronidazole gel from the second postoperative day until seton removal. The new-type seton was associated with significant reductions in recurrence rate, length of stay and healing time compared with the conventional seton, but there were no significant differences in operation time or postoperative incontinence rates. It is concluded that the new-type seton with irrigating tube can improve the treatment of high complex anal fistula.

Identification of epithelialization in high transsphincteric fistulas

Background

At present, transanal advancement flap repair (TAFR) is the treatment of choice for transsphincteric fistulas passing through the upper and middle third of the external anal sphincter. It has been suggested that epithelialization of the fistula tract contributes to the failure of the treatment. The aim of this study was to assess the prevalence of epithelialization of the fistula tract and to study its effect on the outcome of TAFR and TAFR combined with ligation of the intersphincteric fistula tract (LIFT).

Methods

Forty-four patients with a high transsphincteric fistula of cryptoglandular origin underwent TAFR. Nine of these patients underwent a combined procedure of TAFR with LIFT. In all patients the fistula tract was excised from the external opening up to the outer border of the external anal sphincter. In patients undergoing TAFR combined with LIFT an additional central part of the intersphincteric fistula tract was excised. A total of 53 specimens were submitted. Histopathological examination of the specimens was carried out by a pathologist, blinded for clinical data.

Results

Epithelialization of the distal and intersphincteric fistula tract was observed in only 25 and 22% of fistulas, respectively. There was no difference in outcome between fistulas with or without epithelialization.

Conclusions

Epithelialization of high transsphincteric fistulas is rare and does not affect the outcome of TAFR and TAFR combined with LIFT.

A new technique for sphincter-preserving anal fistula repair using a novel radial emitting laser probe

Anal fistula repair still remains challenging. Up to 30% of fistulas persist after surgery despite many improvements in surgical skills and technique. One major reason for surgical failure is a persistent fistula track or remnants of the fistula epithelium which could not be removed during surgery. To overcome this problem, a novel technique was developed using a newly invented radial emitting laser probe ("FiLaC™", Biolitec, Germany) to destroy the fistula epithelium and to simultaneously obliterate the remaining fistula track. In a pilot study, we operated on 11 patients with cryptoglandular anal fistula. All patients underwent previous surgery up to 6 times prior to definitive surgery. In the primary operation, the initial abscess was drained, the internal opening of the fistula identified and seton drainage placed. During fistula repair, we used the flap technique for conventional closure of the internal opening. The remaining fistula track was cleaned mechanically, the laser inserted into the track and energy applied homogeneously at a wavelength of 1,470 nm and 13 watt. While providing continuous retraction of the probe, the remaining epithelium was destroyed and the fistula track obliterated. The median follow-up was 7.4 months. Nine out of 11 fistulas showed primary healing (81.8%). Only one minor form of incontinence (limited soiling) was observed and no complications occurred. The use of a novel diode laser source and a radial emitting laser probe in addition to conventional surgery is a very promising new technique in sphincter-preserving anal fistula repair. The observed healing rate is high. Due to minimized trauma to the sphincter muscle, there are good short-term functional results without observable procedure-related complications.

Thread-dragging therapy in treatment of a rat model of infected subcutaneous fistula

OBJECTIVE

This study was to develop an experimental rat model of subcutaneous fistula induced by bacteria infection and treat it with thread-dragging therapy.

METHODS

A spring-gauze was surgically implanted into 24 male Sprague-Dawley rats' dorsal muscles, respectively, then mixed Staphylococcus aureus and Escherichia coli were injected into the spring-gauze. After 45 d, all the spring-gauzes were removed from the rats under anesthesia. X-ray and ultrasound were performed to assess the fistula tract. Each rat was examined by a fistula probe and four rats were randomly selected for histological assessment. The residual rats were randomly divided into two groups. Group A was treated with thread-dragging therapy, and group B was treated with fistulotomy. The healing time and body weight of the two groups were compared.

RESULTS

On the 45th day of the spring-gauze implantation, imaging assessment proved a tract with two openings in all rats and histological results proved that lumen and surrounding granulation tissue with epithelium were similar to the features of fistula in human beings. The mean healing time of rats in group A was shorter than that of the rats in group B (P<0.01). The body weight of rats in group A was heavier than that of the rats in group B on the 7th and 14th day after surgery, respectively (P<0.05).

CONCLUSION

A rat model of subcutaneous fistula induced by mixed Staphylococcus aureus and Escherichia coli infection was successfully established. Traditional Chinese medicine thread-dragging therapy is less invasive and safer than fistulotomy.

Management of idiopathic anal fistula using cross-linked collagen: a prospective phase 1 study

AIM

Fibrin glue and porcine intestinal submucosa are used in novel sphincter-preserving techniques to heal anal fistulae. However, their success is highly variable and decreases with the length of follow up. The aim of this study was to assess the safety, feasibility and potential efficacy of another novel agent, cross-linked collagen, in two different physical formats, to heal anal fistulae.

METHOD

Prospectively recruited patients underwent symptom, continence and anal physiology assessments and magnetic resonance imaging. Patients with secondary tracts or acute sepsis were excluded. At operation, participants were randomized to receiving a solid collagen implant or collagen fibres suspended in fibrin glue. Follow up included repeat symptom, continence and physiological assessments at 3 months, and regular clinical review thereafter.

RESULTS

Twenty-nine of 43 entrants were eligible for inclusion. Thirteen patients received the collagen implant, and 16 collagen-fibrin glue. Three months postoperation, no patient experienced acute sepsis or continence disturbance, and sphincter function and integrity were unchanged. At 29 months, 12 of 15 (one lost to follow up) patients treated with collagen-fibrin glue were healed, compared with seven of 13 who received the implant.

CONCLUSION

In the short-to-medium term, both techniques are safe and equally effective. The results justify continued research into the use of biomaterials to heal anal fistulae.

Histological identification of epithelium in perianal fistulae: a prospective study

AIM

A procedure often performed following fistulotomy and advancement flap is curettage of the fistula tract after fistulotomy or after closing the internal opening. Epithelialization of the fistula tract might prevent closure of the fistula tract. The aim of this study was to assess the incidence and origin of epithelialization of the fistula tract in patients with perianal fistulae undergoing fistulotomy.

METHOD

Only patients with low perianal fistulae that were surgically treated by fistulotomy were included. Surgical biopsies were taken from the fistula tract from three different locations; on the proximal side at the internal opening, in the middle of the fistula tract and near the distal end close to the external opening.

RESULTS

In the study period, 18 patients with low perianal fistulae were included. In 15 of the 18 patients, squamous epithelium was found at least in one of the biopsies taken from the fistula tract. Epithelium was predominantly found near the internal opening. There was no relation between the duration of fistula complaints and the amount of epithelialization (P = 0.301). The amount of epithelium was not related to the presence of a history of fistula surgery (P = 1.000).

CONCLUSION

This study demonstrated epithelialization in the fistula tract in the majority of the patients surgically treated by fistulotomy for low perianal fistulae. Curettage of perianal fistulae must therefore be considered an essential step in the surgical treatment of perianal fistula.

Seton drainage and fibrin glue injection for complex anal fistulas

OBJECTIVE

The study aimed to evaluate the efficacy of fibrin glue in the treatment of complex anal fistula.

METHOD

Thirty consecutive patients with a complex anal fistula underwent glue instillation after an 8 week period of seton drainage. Cure was defined as complete closure of any secondary opening, absence of fistula seepage, and no abscess formation.

RESULTS

The mean age of the patients (15 males) was 40.5 (range, 22.8-69.1) years. The mean duration of follow-up was 11.7 (range, 0.2-33.5) months. Complete closure of the fistula was achieved in 17 patients at 1 month but in two patients a delayed abscess occurred. At the end of follow-up, 15 (50%) patients were considered to have been cured. The success rate was no different in cases of Crohn's disease or when postoperative antibiotic therapy was given. There was, however, a significant difference in success following regional vs general anaesthesia (68.4 vs 18.2% success, P = 0.02).

CONCLUSION

Fibrin glue cured 50% of our first 30 patients, and regional anaesthesia was predictive of success.

Perianal fistulae in Crohn's Disease: current and future approaches to treatment

: affecting sphincter integrity and continence. Traditional surgical and medical approaches are not without their limitations and may result in either comorbidity, such as fecal incontinence, or incomplete healing of the fistulae. Over the last 2 decades these limitations have led to a paradigm shift toward the use of biomaterials, and more recently cell-based therapies, which have met with variable degrees of success. This review discusses the traditional and current methods of treatment, as well as emerging and possible alternative approaches that may improve fistula healing.

Lateral buttock and postanal congenital dermal sinus tract

We present 2 rare cases of lateral buttock and postanal congenital dermal sinus tract. These 2 children were noted to have a pit in the left upper lateral buttock and a postanal orifice after birth. Magnetic resonance imaging, computed tomography, and ultrasonography showed an inflammatory mass lesion in the buttock and a funicular structure adjacent to the rectum. Fistulography showed no connection between the pit and orifice. Surgical exploration revealed firm tracts from both the lateral buttock and postanus running deep to the tip of the coccyx. Histopathologic findings showed squamous cells in the walls of the sinus tracts. Our report broadens the clinical literature regarding congenital dermal sinus tract. We postulate that this disease may not always have a connection with the central nervous system, and our cases may provide examples of anal fistulas of congenital etiology in infants.

Etiology of perianal Crohn's disease: role of genetic, microbiological, and immunological factors

Perianal fistulation is a common complication of Crohn's disease (CD). Fistulating perianal CD appears to represent a distinct phenotype of CD, separate from luminal fistulating disease, with differing disease behavior and which often requires different therapeutic strategies. The etiology of Crohn's perianal fistulae appears to have genetic, microbiological, and immunological components. Relationships with IBD5, which codes for the organic/cation transporter and IRGM, important in the autophagy pathway, have been identified but further genetic associations remain elusive. The partially efficacious use of antibiotics and fecal diversion imply a microbiological component and, similarly, the partial efficacy of immunosuppressants and anti-tumor necrosis factor alpha (TNFalpha) treatments suggest not only that an immunological process is taking place, but also that microbiota alone cannot account for the pathogenesis. Recent work implicates failures in the tissue injury/repair process with myofibroblasts, matrix metalloproteinases, and an epithelial-to-mesenchymal transition being possible culprits. We examine these areas in a review of the current understanding of the etiology of Crohn's perianal fistulae.

An experimentally successful new sphincter-conserving treatment for anal fistula

PURPOSE

A new sphincter-conserving treatment was evaluated in a porcine model.

METHODS

A total of 36 fistulas were created by procedures that have been published previously. At fistula induction a skin biopsy was taken from which to culture fibroblasts. Four weeks after induction, when fistulas were well established, the fistula tracks were cored out. Collagen paste modified from Permacol injection (Covidien, Mansfield, MA) was then used as a solitary infill material in 11 tracks, cultured autologous fibroblasts being added to this in a further 18 tracks. The track was cored out in seven controls, but these tracks were not treated with infill material. All of the internal and external openings were closed. Anorectal excision was then carried out under terminal anesthesia at 2 to 12 weeks. Histologic examination of individual tracks was performed by an experienced pathologist.

RESULTS

In this quadruped all of the infilled tracks healed, autologous fibroblasts having the best tissue integration, but only two of seven control tracks healed.

CONCLUSIONS

Removal of the fistula track followed by injection of collagen healed all of the cases. The addition of autologous fibroblasts improved the histologic appearance of the tracks. A pilot study in human fistula patients is in progress.

Antimicrobial peptides in chronic anal fistula epithelium

OBJECTIVE

Anal fistulas are the result of chronic infection of an intersphincteric gland. Despite the passage through mesenchymal tissue, fistulas seldom lead to systemic infection. Antimicrobial peptides are secreted by a variety of epithelia, belonging to the innate immune system and are potential factors contributing to infection control. The aim of this study was to investigate whether epithelium is present in the fistulas and what the origin might be.

MATERIAL AND METHODS

Forty-seven chronic anal fistulas from patients, excluding Crohn's disease, were compared with healthy rectal and perianal control tissue. Expression of antimicrobial peptide mRNA was analysed by real-time polymerase chain reaction (RT-PCR) and immunohistochemistry. Tissue was further studied by cytokine and cytokeratin staining.

RESULTS

Chronic anal fistulas express high levels of hBD-2 and hBD-3 and the newly identified antimicrobial peptides RNase7 and psoriasin compared to rectal mucosa from control patients. Perianal skin has almost identical levels of RNase7 and psoriasin expression to those in fistulas. IL-1b and IL-8 were the only cytokines detectable in fistulas. Fistulas are lined with squamous epithelium that expresses identical cytokeratines as skin.

CONCLUSIONS

Epithelialization and local production of antimicrobial peptides in anal fistulas serve as defence mechanisms to prevent local and systemic infection by microbes from faeces passing through the fistula tract.

Percutaneous gelfoam embolization of chronic enterocutaneous fistulas: report of three cases

PURPOSE

A relatively simple radiologically guided method for the treatment of enterocutaneous fistula by gelfoam embolization is described.

METHODS

Three cases of chronic enterocutaneous fistula are presented. In each case, a sheath was positioned with its tip at the enteric opening of the fistula. Gelfoam was injected to occlude the fistula at its enteric opening.

RESULTS

In each case, there was successful closure of the fistula.

CONCLUSIONS

Radiologically guided embolization with gelfoam is a safe, relatively simple procedure, which may be useful in the treatment of chronic enterocutaneous fistula.

Pilot study: fibrin sealant in anal fistula model

PURPOSE

The aim of this study was to investigate the failure of fibrin sealant treatment for fistula-in-ano in an experimental porcine model and to determine histologic changes associated with the sealant and setons.

METHODS

Three surgically created fistulas were treated by seton drainage in each of eight male pigs. After 26 days, magnetic resonance imaging was performed and setons were removed. Two pigs were killed as controls for stereologic histologic fistula track assessment. In six, fistulas were curetted, and in four the fistulas were treated with fibrin sealant. In these four sealant and two seton pigs, magnetic resonance imaging was repeated a median of 47.5 days after fistula formation. The pigs were killed and stereologic histologic fistula track examination was performed to determine granulation tissue and fistula lumen volumes. These values were compared among control, seton, and sealant groups over time, and related to fistula volumes derived from magnetic resonance imaging.

RESULTS

Sealant was not visible microscopically within tracks, although some sections revealed a foreign body-type reaction. On stereologic assessment, granulation tissue volumes were smaller in sealant and seton groups than in controls (median, 88 vs. 187 vs. 453 mm3, respectively; P = 0.002) and decreased over time (median, 408 and 152 mm3 (Day 42) vs. 88 and 75 (Day 53), respectively; P = 0.002). Fistula lumen (P < 0.001), and granulation tissue combined with fistula lumen volumes (P = 0.002) were similarly smaller. Magnetic resonance imaging of fistula intensity was less in the sealant group than in the seton group and controls (mean, 777 vs. 978 vs. 1214 units/mm2, P = 0.003). Magnetic resonance imaging fistula volumes were least in sealant and seton groups vs. controls (P = 0.024), decreasing significantly in the sealant group over time (P = 0.018). No direct relationship was found between imaging and histologic volumes.

CONCLUSIONS

In an experimental porcine model of anal fistula, granulation tissue was still present, albeit diminished, following track curettage combined with seton or sealant therapy, and was minimal in the sealant group, confirming some benefit from this procedure. Eradication of all longstanding granulation tissue may ensure complete success of fibrin sealant therapy.

Experimental model of fistula-in-ano

PURPOSE

This study was designed to create and evaluate an experimental porcine model of fistula-in-ano.

METHODS

Initial cadaveric dissection enabled refinement of the technique for fistula formation and histoanatomical study of the porcine anal canal. Subsequently, three surgically created fistulas were treated by seton drainage in each of eight male pigs (weight, 38-41 kg). After 26 days, magnetic resonance imaging at 1.5 Tesla was performed and setons removed under general anesthesia, enabling clinical and microbiologic track assessment. Two pigs were killed for histologic fistula track assessment.

RESULTS

Histoanatomical assessment noted a rudimentary internal anal sphincter, together with structures resembling anal glands. Artificial fistulas persisted during seton drainage and were more often associated with fecal than skin-derived organisms compared with both perineal and anal canal swabs (P = 0.002). All six fistulas assessed histologically had a lumen, and abundant surrounding granulation tissue similar to that seen in human fistula-in-ano. Epithelialization was not evident in any track. Fistulas were visualized as high signal tracks using magnetic resonance imaging.

CONCLUSIONS

Porcine anal anatomy resembles that of humans, and an experimental model proved suitable when assessed by magnetic resonance imaging, microbiology, and histologically, which demonstrated abundant granulation tissue. This model could be further used to investigate fistula treatments.

Fibrin glue in the management of anal fistulae

OBJECTIVE

Fibrin glue has been used as a sphincter sparing approach for the treatment of anal fistulae for two decades. However, there is uncertainty about its short and long-term efficacy. The objective of this review was to ascertain the role of fibrin glue in the management of anal fistulae, including assessment of recurrence rates, continence disturbance and other complications.

METHODS

We searched Medline (January 1966 to February 2004), the Cochrane database, and EMBASE using the terms anal fistulae, fistula-in-ano, and fibrin glue. Relevant papers from the reference lists of these articles and from the authors' personal collections were also reviewed. A systematic review of all articles relating to the use of fibrin glue in the treatment of anal fistulae was performed. This included 19 studies. Reviewers performed data extraction independently. Outcomes evaluated included recurrence rates, continence disturbance, septic complications, adverse drug reactions, and duration of follow-up. Heterogeneity of the clinical trials made direct comparisons difficult and meta-analysis impossible.

RESULTS

The success rates reported in published studies range from 0% to 100%. Differences in patient selection (including fistula aetiology and type), treatment protocols, and follow-up duration may contribute to such diverse results.

CONCLUSIONS

Fibrin glue is simple to use, has a minimal morbidity and should not affect later treatment options in the event of its failure. It is therefore theoretically attractive as a first line treatment in the management of those types of anal fistula in which it has been shown to work. However, further research into 'biological' glues is merited and these subject to randomised controlled study.

Imaging anal fistula

The management of fistula-in-ano has been based on digital examination and operative findings. MR imaging has shown significant limitations to this approach, particularly in the management of recurrent fistula. The most cost-effective approach may be using a combination of endosonography and MR imaging. Preoperative confirmation of fistula complexity facilitates surgery planning of sphincter saving techniques and prevents sepsis being missed, which has been shown to reduce recurrence. Imaging has a significant role to play in this condition to improve patient outcome.

Anal gland carcinoma

BACKGROUND

Anal gland carcinoma is a rare entity. The authors conducted a joint study of cases coded as definite or possible anal gland carcinoma from the archives of the Armed Forces Institute of Pathology and the Canadian Reference Center for Cancer Pathology.

METHODS

Seven cases of potential anal gland carcinoma were identified from the Canadian files and 12 from the Armed Forces Institute of Pathology archives. Of these 19 cases, 14 had adequate material to allow clinical, histologic, and immunohistochemical analysis.

RESULTS

Seven of these 14 cases met a modified World Health Organization (WHO) definition of anal gland carcinoma. The mean age of these patients was 66 years (range, 60-72 years), with a male-to-female ratio of 6:1. The tumors were composed of haphazardly dispersed, small glands with scant mucin production that invaded the wall of the anorectal area with no obvious intraluminal component observed clinically or microscopically. Immunohistochemical studies were performed on all seven of these cases, revealing cytokeratin (CK) 7+/CK 20- expression in six cases, and CK 7+/CK 20+ expression in one case. The remaining seven cases showed no intraluminal component but did not meet a modified WHO definition of anal gland carcinoma. This group included three mucinous adenocarcinomas (two clinically arising in anal fistulas), all of which were CK 7+/CK 20+, and a rectal-type adenocarcinoma that was CK 7-/CK 20+. There was also a tumor interpreted as probable rectal-type adenocarcinoma that was CK 7+/CK 20+, and a tumor interpreted as probable squamous cell carcinoma that was CK 7-/CK 20-. The seventh tumor in this group, which could not be classified, was CK 7+/CK 20-.

CONCLUSIONS

A useful and discriminating definition of anal gland carcinoma is an anal canal tumor composed of haphazardly dispersed, small glands with scant mucin production invading the wall of the anorectal area without an intraluminal component. The glands are positive for CK 7.

Anocutaneous advancement flap closure of high anal fistulas

BACKGROUND

Fistula-in-ano may be treated by closing the internal fistulous opening. An anocutaneous flap was developed to facilitate this closure.

METHODS

From October 1995 to April 1997, 40 patients with high trans-sphincteric or suprasphincteric anal fistulas were treated. The important components of the procedure are excision of the internal opening, excision or curettage of the tract, closure of the internal opening by an anocutaneous flap, and external drainage.

RESULTS

In two patients (5 per cent) the flap separated and the sutured internal opening was exposed. One of the two was healed 4 weeks later. In the remaining 38 patients, complete healing occurred 2-3 weeks after operation. No patient was incontinent of gas or stool.

CONCLUSION

This procedure is technically simple, heals rapidly with minimal scarring, and cures anal fistulas while preserving the anal sphincter.

Anorectal abscess and fistula

Anorectal abscesses and fistulas are seen commonly in the primary care practice. An abscess forms as the result of obstruction of an anal gland, with resulting retrograde infection. An anal fistula simply represents the chronic phase of a perianal abscess. The history generally is diagnostic, and special studies usually are not required. Treatment is surgical, with good results.