The role of anal ultrasound in the management of anal fistulas

Practical approach to linear endoscopic ultrasound examination of the rectum and anal canal

Standard endosonographic examination of the rectal area is usually performed with radial endoscopic ultrasound (EUS). However, in recent years, widespread availability of linear EUS for assessing various anatomical regions in the gastrointestinal tract has facilitated its use in the assessment of anorectal disorders. Currently, many rectal and anal diseases, including perianal abscesses, fistulae, polyps, and neoplastic lesions, can be well-visualized and evaluated with linear EUS. The aim of this review is to shed light on the anatomy and systematic examination of the anorectal region with linear EUS and clinical implications for different anorectal pathologies.

New horizons in the imaging of perianal Crohn's disease: transperineal ultrasonography

perianal disease, most commonly manifest as fistula or abscess formation, affects up to 40% of patients with crohn's disease. perianal crohn's disease is disabling, associated with poor outcomes, and represents a therapeutic challenge for physicians. correct diagnosis and classification of perianal disease is the first crucial step for appropriate multidisciplinary management. Areas covered: A literature search was performed of the PubMed database using the terms 'transperineal ultrasonography', 'transperineal ultrasound', 'perianal disease', 'perianal fistula', 'perianal abscess', 'magnetic resonance', 'endoanal ultrasonography', 'endoscopic ultrasound' in combination with 'Crohn's disease'. A comprehensive review of the relative advantages and disadvantages of the various methods of evaluation of perianal Crohn's disease is provided. A particular focus is placed on transperineal ultrasonography, including historical and technical factors, advantages and limitations, and its current role in practice. An algorithm for integration of transperineal ultrasound into the management of perianal Crohn's disease into clinical practice is proposed, along with future areas research. Expert commentary: Transperineal ultrasound is a simple, safe, cheap and reliable imaging technique for evaluation of perianal Crohn's disease, which should be used more frequently in clinical practice.

Three-dimensional endoanal ultrasound for diagnosis of perianal fistulas: Reliable and objective technique

AIM: To evaluate accuracy of three-dimensional endoanal ultrasound (3D-EAUS) as compared to 2D-EAUS and physical examination (PE) in diagnosis of perianal fistulas and correlate with intraoperative findings.

METHODS: A prospective observational consecutive study was performed with patients included over a two years period. All patients were studied and operated on by the Colorectal Unit surgeons. The inclusion criteria were patients over 18, diagnosed with a criptoglandular perianal fistula. The PE, 2D-EAUS and 3D-EAUS was performed preoperatively by the same colorectal surgeon at the outpatient clinic prior to surgery and the fistula anatomy was defined and they were classified in intersphincteric, high or low transsphincteric, suprasphincteric and extrasphincteric. Special attention was paid to the presence of a secondary tract, the location of the internal opening (IO) and the site of external opening. The results of these different examinations were compared to the intraoperative findings. Data regarding location of the IO, primary tract, secondary tract, and the presence of abscesses or cavities was analysed.

RESULTS: Seventy patients with a mean age of 47 years (range 21-77), 51 male were included. Low transsphincteric fistulas were the most frequent type found (33, 47.1%) followed by high transsphincteric (24, 34.3%) and intersphincteric fistulas (13, 18.6%). There are no significant differences between the number of IO diagnosed by the different techniques employed and surgery (P > 0.05) and, there is a good concordance between intraoperative findings and the 2D-EAUS (k = 0.67) and 3D-EAUS (k = 0.75) for the diagnosis of the primary tract. The ROC curves for the diagnosis of transsphincteric fistulas show that both ultrasound techniques are adequate for the diagnosis of low transsphincteric fistulas, 3D-EAUS is superior for the diagnosis of high transsphincteric fistulas and PE is weak for the diagnosis of both types.

CONCLUSION: 3D-EAUS shows a higher accuracy than 2D-EAUS for assessing height of primary tract in transsphincteric fistulas. Both techniques show a good concordance with intraoperative finding for diagnosis of primary tracts.

Endoanal ultrasound in perianal fistulae and abscesses

Endoanal ultrasound is a technique that provides imaging of the anal sphincters and its surrounding structures as well as the pelvic floor. However, endoanal magnetic resonance imaging (MRI) is preferred by most physicians, although costs are higher and demand easily outgrows availability. Endoanal ultrasound is an accurate imaging modality delineating anatomy of both cryptoglandular as well as Crohn perianal fistula and abscess. Endoanal ultrasound is comparable with examination under anesthesia and equally sensitive as endoanal MRI in fistula detection. When fistula tracts or abscesses are located above the puborectal muscle, an additional endoanal MRI should be performed. Preoperative imaging is advocated in recurrent cryptoglandular fistula because a more complex pattern can be expected. Endoanal ultrasound can help avoid missing tracts during surgery, lowering the chance for the fistula to persist or recur. It can easily be performed in an outpatient setting and endosonographic skills are quickly incremented. Costs are low and endoanal ultrasound has the potential to improve outcome of patients with both cryptoglandular and fistulizing Crohn disease; therefore, it values more attention.

Impact of three-dimensional endoanal ultrasound on the outcome of anal fistula surgery: a prospective cohort study

AIM

The aim of the study was to evaluate the impact of three-dimensional endoanal ultrasound (3D-EAUS) on postoperative outcome in patients with anal fistula.

METHOD

This prospective study compared clinical and functional outcomes of patients with and without preoperative 3D-EAUS examination 1 year after anal fistula surgery. Patients were prospectively followed and evaluated by a standardized protocol including physical examination, the Wexner Incontinence Score (WIS) and anorectal manometry, at baseline and 1 year after surgery.

RESULTS

A total of 196 patients were enrolled. There were no significant differences in demographic and operative parameters, except for operation time, between the two groups. At 1 year follow-up, the overall recurrence rates were 8.8% (9/102) in the 3D-EAUS group and 13.8% (13/94) in the examination under anaesthesia (EUA) group. In the subgroup of patients with complex fistulae, the recurrence rate was numerically lower in the 3D-EAUS group (12.8% vs 22.5%; P = 0.26). The WIS in the EUA group significantly worsened (0.35 ± 0.94 vs 1.07 ± 1.59; P = 0.003) with a decreased the number of fully continent patients (82.5% vs 55%; P = 0.008) while neither the WIS nor the proportion of fully continent patients changed in the 3D-EAUS group. Fewer patients in the 3D-EAUS group developed incontinence postoperatively (6.7% vs 33.3%; P = 0.012) and they had better maximum resting pressure and maximum squeeze pressure than the EUA group.

CONCLUSIONS

Preoperative use of 3D-EAUS had a favourable impact on the outcome of surgical treatment for anal fistulae, especially in those with complex anal fistula. It should be routinely used in the clinical setting.

Usefulness of 3D transperineal ultrasound in severe stenosis of the anal canal: preliminary experience in four cases

Background

Organic or functional anal canal stenoses are uncommon conditions that occur in the majority of cases as a consequence of anal diseases. A proper assessment is fundamental for decision making; however, proctological examination and endoanal ultrasound are often unfeasible or very difficult to perform even under local or general anesthesia. We therefore began to use 3D transperineal ultrasound to assess patients. The aim of this study was to compare the results of evacuation proctography and 3D transperineal ultrasound in patients with severe anal canal stenosis.

Methods

Four consecutive patients with high-grade anal canal stenosis were evaluated using both proctography and 3D transperineal ultrasound with a micro-convex transducer between March and June 2011.

Results

In all cases, 3D transperineal ultrasound provided detailed information on the length and level of stenosis and on the integrity of the anal sphincters.

Conclusions

Our preliminary experience suggests that 3D transperineal ultrasound makes it possible to plan optimal surgical treatment.

Collagen matrix injection combined with flap repair for complex anal fistula

Several biomaterials have been proposed to treat anal fistula alone or in combination with other surgical procedures aiming to reduce recurrence rates while minimizing continence impairment. More recently a porcine dermal matrix injection has been proposed as infill biomaterial to treat fistulae. We propose an approach consisting of non-cutting seton positioning followed several weeks later by flap repair associated with dermal matrix injection into the fistula tracts. We report our experience with this two-staged procedure on 24 consecutive patients with complex anal fistulae with a median follow up of > 12 months. In our experience this two-stage approach seems to be safe and effective.

A diagnostic accuracy meta-analysis of endoanal ultrasound and MRI for perianal fistula assessment

BACKGROUND

Imaging modalities such as endoanal ultrasound or MRI can be useful preoperative adjuncts before the appropriate surgical intervention for perianal fistulas.

OBJECTIVES

We present a systematic review of published literature comparing endoanal ultrasound with MRI for the assessment of idiopathic and Crohn's perianal fistulas.

DESIGN

A meta-analysis was performed to obtain pooled values for specificity and sensitivity.

SETTINGS

Electronic databases were searched from January 1970 to October 2010 for published studies.

PATIENTS AND INTERVENTIONS

Four studies were used in our analysis. There were 241 fistulas in the ultrasound group and 240 in the magnetic resonance group.

RESULTS

The combined sensitivity and specificity of magnetic resonance for fistula detection were 0.87 (95% CI: 0.63-0.96) and 0.69 (95% CI: 0.51-0.82). There was a high degree of heterogeneity between studies reporting on MRI sensitivity (df = 3, I = 93%). This compares to a sensitivity and specificity for endoanal ultrasound of 0.87 (95% CI: 0.70-0.95) and 0.43 (95% CI: 0.21-0.69). There was a high degree of heterogeneity between studies reporting on endoanal ultrasound sensitivity (df = 3, I = 92%).

CONCLUSIONS

From the available literature, the summarized performance characteristics for MRI and endoanal ultrasound demonstrate comparable sensitivities at detecting perianal fistulas, although the specificity for MRI was higher than that for endoanal ultrasound. Both specificity values are considered to be diagnostically poor, however. The high degree of data heterogeneity and the shortage of applicable studies precludes any firm conclusions being made for clinical practice. Future trials with improved study design (including prospective data collection and consideration of verification bias) may help to further clarify the role of MRI in the assessment and treatment response monitoring of perianal fistulas (particularly in patients with Crohn's disease).

Porcine dermal collagen matrix injection may enhance flap repair surgery for complex anal fistula

INTRODUCTION

The use of biomaterials to treat anal fistula has drawn great interest. More recently, a porcine dermal matrix injection has been proposed as infill biomaterial to treat fistulas.

METHODS

We propose a novel approach consisting in non-cutting seton positioning followed by flap repair associated with dermal matrix injection into the fistula tracts after several weeks.

RESULTS

We report our experience with this two-staged procedure on 11 consecutive patients with recurrent high trans-sphincteric fistulas with a minimum follow-up of 6 months.

CONCLUSIONS

In our experience, this two-stage approach seems to be safe and effective.

The accuracy of a postprocessing technique--volume render mode--in three-dimensional endoanal ultrasonography of anal abscesses and fistulas

OBJECTIVE

This study aimed to evaluate the accuracy of a 3-dimensional volume render mode endoanal ultrasonography in the assessment of anal abscesses and fistulas.

PATIENTS AND METHODS

Three-dimensional endoanal ultrasonography was performed preoperatively in 62 patients with clinical diagnoses of an anal abscess and/or an anal fistula. The accuracy of a volume render mode endoanal ultrasonography was evaluated blindly by 2 observers through a retrospective analysis of all the stored images of anal abscesses and fistulas. Differences in classification of the type of anal abscesses and in determination of the type and location of internal openings of anal fistulas were assessed.

RESULTS

In classification of the primary tract, the agreement between the volume render mode endoanal ultrasonography and surgery was much higher than that for the 3-dimensional endoanal ultrasonography (marginal homogeneity test P > .1, κ = 0.96, and marginal homogeneity test P = .0048, κ = 0.28, respectively). In localizing the internal openings and in classifying anal abscesses, the agreement for both methods with surgery was identical. The interobserver agreement showed complete agreement (100%) with regard to luminance and thickness parameters and very high accuracy for the opacity and filter parameters.

CONCLUSIONS

This study demonstrated that volume render mode endoanal ultrasonography is a useful adjunct method to the 3-dimensional endoanal ultrasonography, showing better classification results of the types of anal fistulas.

The role of 3-dimensional anorectal ultrasonography in the assessment of anterior transsphincteric fistula

PURPOSE

The aim of this study was to evaluate the role of 3-dimensional anorectal ultrasonography in the choice of surgical technique according to the position of the fistulous tract in patients with anterior transsphincteric anal fistula.

METHODS

A total of 33 patients (18 male) with anterior transsphincteric fistulas were evaluated by ultrasonography. The length of the external and internal anal sphincters, the position of the internal opening, the length of the compromised sphincter, and the percentage of sphincter muscle to be transected during surgery were measured, compared between sexes, and used in planning the surgery. Postoperative incontinence symptoms were quantified with a Wexner score.

RESULTS

The external and internal sphincters were longer and the position of the internal opening was higher in males. The position where the tract crossed the external sphincter was in both sexes, but the percentage of compromised muscle was higher in females because of the smaller length of the external sphincter. Seton placement followed by fistulotomy or advanced flap repair were indicated in 11 of 18 males and 13 of 15 females as the tract crossed the external sphincter above 50.0%. The mean postoperative follow-up was 12 months. Overall, minor fecal incontinence symptoms were identified in 16 (48.0%) patients. Of these, 11 (73.0%) females and 5 (28.0%) males had a mean incontinence score of 2.9 and 3.0, respectively.

CONCLUSIONS

Three-dimensional ultrasonography was shown to be useful in the preoperative assessment of anterior transsphincteric fistulas by quantifying the length of muscle to be transected, contributing to the choice of a safe treatment approach and to the reduction of the rate of postoperative continence disorders.

Three-dimensional endoanal ultrasonographic assessment of an anal fistula with and without H2O2 enhancement

AIM: To evaluate the effectiveness of three-dimensional endoanal ultrasound (3D-EAUS) in the assessment of anal fistulae with and without H₂O₂ enhancement.

METHODS: Sixty-one patients (37 males, aged 17-74 years) with anal fistulae, which were not simple low types, were evaluated by physical examination and 3D-EAUS with and without enhancement. Fistula classification was determined with each modality and compared to operative findings as the reference standard.

RESULTS: The accuracy of 3D-EAUS was significantly higher than that of physical examination in detecting the primary tract (84.4% vs 68.7%, P = 0.037) and secondary extension (81.8% vs 62.1%, P = 0.01) and localizing the internal opening (84.2% vs 59.7%, P = 0.004). A contrast study with H₂O₂ detected several more fistula components including two primary suprasphincteric fistula tracks and one supralevator secondary extension, which were not detected on non-contrast study. However, there was no significant difference in accuracy between 3D-EAUS and H₂O₂-enhanced 3D-EAUS with respect to classification of the primary tract (84.4% vs 89.1%, P = 0.435) or secondary extension (81.8% vs 86.4%, P = 0.435) or localization of the internal opening (84.2% vs 89.5%, P = 0.406).

CONCLUSION: 3D-EAUS was highly reliable in the diagnosis of an anal fistula. H₂O₂ enhancement was helpful at times and selective use in difficult cases may be economical and reliable.

[Comparison of hydrogen peroxide-enhanced ultrasound with surgery in the diagnosis of perianal fistulas]

PURPOSE

To evaluate the usefulness of hydrogen peroxide-enhanced ultrasound (H(2)O(2)) in the preoperative assessment of perianal fistulas and to compare these results with unenhanced ultrasound findings.

METHODS

All patients with surgically confirmed perianal fistula who underwent preoperative enhanced and unenhanced ultrasound were included. We compared enhanced and unenhanced ultrasound findings with surgical results (chi(2) and McNemar tests).

RESULTS

A total of 44 surgically treated patients were analysed. Hydrogen peroxide-enhanced ultrasound correctly identified primary fistula tracks in 34 patients (sensitivity of 77%), 100% of abscesses and the internal opening in 29 out of 37 identified with surgery (sensitivity of 78% and specificity of 70%). The use of hydrogen peroxide provided additional information to the ultrasound performed without the use of contrast enhancement in 32 of the 44 patients (73%). H(2)O(2) increased the number of fistula tracts correctly detected (77% vs 45%; p<0.003), particularly suprasphincteric fistulas, as well as internal openings (78% vs 22%; p<0.001) and secondary tracks (70% vs 0%). Additional detection of fistula tracks after H(2)O(2) injection was higher in patients with previous surgery (68% vs 35%; p<0.05).

CONCLUSIONS

Hydrogen peroxide-enhanced ultrasound shows good agreement compared with surgical findings in the assessment of perianal fistulas. H(2)O(2) improves conventional ultrasound results, increasing the detection of fistula tracks and internal openings, and also providing additional information, particularly in previously operated patients.

Current techniques in imaging of fistula in ano: three-dimensional endoanal ultrasound and magnetic resonance imaging

Perianal fistula is an abnormal communication between the anal canal and perianal skin. The majority of perianal fistulous disease results from either cryptoglandular inflammation or Crohn's disease. These groups differ in pathophysiology, prognosis, and strategies for imaging and treatment. Endoanal ultrasound and magnetic resonance imaging represent current imaging strategies for evaluating perianal fistulas and may be used alone or in combination. The use of three-dimensional technique and peroxide fistulography optimize the ultrasound evaluation of perianal fistula. The use of multiple imaging planes and sequences including fat suppression and contrast enhancement optimize the magnetic resonance imaging protocol. Examples of the imaging appearance of perianal fistulas and a proposed flowchart for imaging modality selection are provided.

Prognostic value of endoanal ultrasound for fistula-in-ano: a retrospective analysis

PURPOSE

This study was designed to assess whether preoperative endoanal ultrasound plays a prognostic role in the surgical outcome of anal fistula.

METHODS

A retrospective review was conducted at a single institution.

RESULTS

Sixty-nine patients underwent 83 studies. Indications for endoanal ultrasound included complex fistulas and tracts, multiple external openings, recurrent fistulas, and/or failed previous surgical intervention. Mean age was 51.7 years. Fifty-three patients (77 percent) were men. Mean duration of symptoms was 3.1 years. Forty-nine patients (71 percent) had undergone previous surgical intervention to eradicate sepsis or fistula. Sixty patients (87 percent) underwent surgical interventions and were divided into two groups: Group A (73.3 percent), concordance with ultrasound findings; and Group B (26.7 percent), nonconcordance. Mean follow-up in the surgical group was 15.6 months. Measured outcome was total number of operations per patient and failure rate of primary surgical intervention. No difference was noted in mean total number of operations between Group A (1.57) and Group B (1.69) (P = 0.71). There was a statistically nonsignificant trend toward a higher failure rate of the primary intervention in the nonconcordance group [failure rate 18.2 percent in Group A vs. 25 percent in Group B (P = 0.72)].

CONCLUSIONS

The findings and accuracy of preoperative endoanal ultrasound did not influence postoperative outcome.

The advantages of volume rendering in three-dimensional endosonography of the anorectum

Anorectal diseases require imaging for proper case management. At present, endoanal ultrasonography and endorectal ultrasonography have become important parts of diagnostic workup of patients with fecal incontinence, perianal fistulas, and rectal cancer and provides sufficient information for clinical decision-making in many cases. However, with the currently available ultrasonographic equipment and techniques, a good deal of relevant information may remain hidden. The advent of high-resolution three-dimensional endoluminal ultrasound, constructed from a synthesis of standard two-dimensional cross-sectional images, and of "Volume Render Mode," a technique to analyze information inside a three-dimensional volume by digitally enhancing individual voxels, promises to revolutionize diagnosis of pelvic floor disorders. By use of the different postprocessing display parameters, the volume-rendered image provides better visualization performance when there are not large differences in the signal levels of pathologic structures compared with surrounding tissues. The anatomic structures in the pelvis, the axial and longitudinal extension of anal sphincter defects, the anatomy of the fistulous tract in complex perianal sepsis, and the presence of slight or massive submucosal invasion in early rectal cancer may be imaged in greater detail. This additional information will bring an improvement for both planning and conduct of surgical procedures.

Endorectal ultrasound (ERUS) in pelvic disorders

Endorectal ultrasound (ERUS) imaging is a complex process using electronic devices to control ultrasound waves and produce images of anatomic structures. It is a simple, cheep and well-tolerated procedure that provides excellent images of rectal and anal canal wall and pelvic floor muscles together with surrounding organs and tissues. The direct imaging of anal canal and pelvic floor muscles with surrounding tissues allows one to identify sphincter defects, anorectal abscesses and fistulas as well as great variety of benign and malignant pathology of the pelvis. Basically, techniques for ERUS are very similar, but there are some slight modifications regarding equipment, indications, and localization of pathologic process. We describe the technique, indications, results and pitfalls of ERUS with the Bruel and Kjaer type 1850 endosonic probe with 7 and 10 MHz transducers in benign pelvic disorders.

Imaging of fistula in ano

Fistula in ano is a common condition that often recurs despite seemingly adequate surgery, usually because of infection that was missed at surgery. It is now increasingly recognized that preoperative imaging can help identify infection that would have otherwise gone unidentified. In particular, magnetic resonance (MR) imaging findings have been shown to influence surgery and markedly diminish the chance of recurrence; thus, preoperative imaging will become increasingly routine in the future. In this article, the authors describe the pathogenesis, classification, and imaging of fistula in ano, with an emphasis on MR imaging. Most important, the authors describe how the radiologist is well placed to answer the surgical riddles that must be solved for treatment to be effective.

Fístula anal de origen criptoglandular. Opciones terapéuticas

Anal fistula is a frequent condition. The most commonly accepted origin is infectious. The most widely used classification is based on cryptoglandular theory and on the position of the fistulous tract in relation to the anal sphincter. Physical examination will help to identify the type of fistula and allow its treatment to be planned. The most widely used complementary tests are endoanal ultrasound and magnetic resonance imaging. We review the various therapeutic options and their results, especially fistulotomy, endorectal advancement flap, use of sedal, anodermal advancement flap, sphincterorrhaphy with sphincter repair, and fibrin glue.

Clinical examination, endosonography, and MR imaging in preoperative assessment of fistula in ano: comparison with outcome-based reference standard

PURPOSE

To prospectively evaluate the relative accuracy of digital examination, anal endosonography, and magnetic resonance (MR) imaging for preoperative assessment of fistula in ano by comparison to an outcome-derived reference standard.

MATERIALS AND METHODS

Ethical committee approval and informed consent were obtained. A total of 104 patients who were suspected of having fistula in ano underwent preoperative digital examination, 10-MHz anal endosonography, and body-coil MR imaging. Fistula classification was determined with each modality, with reviewers blinded to findings of other assessments. For fistula classification, an outcome-derived reference standard was based on a combination of subsequent surgical and MR imaging findings and clinical outcome after surgery. The proportion of patients correctly classified and agreement between the preoperative assessment and reference standard were determined with trend tests and kappa statistics, respectively.

RESULTS

There was a significant linear trend (P < .001) in the proportion of fistula tracks (n = 108) correctly classified with each modality, as follows: clinical examination, 66 (61%) patients; endosonography, 87 (81%) patients; MR imaging, 97 (90%) patients. Similar trends were found for the correct anatomic classification of abscesses (P < .001), horseshoe extensions (P = .003), and internal openings (n = 99, P < .001); endosonography was used to correctly identify the internal opening in 90 (91%) patients versus 96 (97%) patients with MR imaging. Agreement between the outcome-derived reference standard and digital examination, endosonography, and MR imaging for classification of the primary track was fair (kappa = 0.38), good (kappa = 0.68), and very good (kappa = 0.84), respectively, and fair (kappa = 0.29), good (kappa = 0.64), and very good (kappa = 0.88), respectively, for classification of abscesses and horseshoe extensions combined.

CONCLUSION

Endosonography with a high-frequency transducer is superior to digital examination for the preoperative classification of fistula in ano. While MR imaging remains superior in all respects, endosonography is a viable alternative for identification of the internal opening.

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.