Quantifying the extent of fistulotomy. How much sphincter can we safely divide? A three-dimensional endosonographic study

Distalization of perianal fistulas after loose silicone seton drainage is a myth

BACKGROUND

It is often stated that loose seton drainage results in distal migration of a fistula tract in perianal fistula. The aim of the present study was to assess this distalization of trans- and suprasphincteric perianal fistulas after a silicone seton has been inserted.

METHODS

Consecutive patients who underwent loose seton placement for the management of a transsphincteric or suprasphincteric fistula between January 2016 and December 2021 with a pre- and postoperative magnetic resonance imaging (MRI) were included in the present retrospective study. The height of the external anal sphincter (EAS) and the level of penetration of perianal fistula through the EAS or puborectal muscle (PRM) were determined on MRI. Primary outcome was migration of the fistula tract through the EAS and PRM.

RESULTS

Thirty-eight patients with perianal fistulas were included. Median height of the EAS was 28 (IQR 25-34) mm before seton placement and 27 (IQR 24-33) mm afterward. Median level of perforation was 32 (IQR 17-40) mm before seton placement and 28 (IQR 17-40) mm afterward (p = 0.37). One fistula (3%) was downgraded from mid to low transsphincteric and was laid open after 14.9 months of loose seton drainage.

CONCLUSIONS

No statistically significant distalization of complex fistula tracts after loose silicone seton drainage was found. Some complex fistulas may downgrade to a less complex fistula after long-term seton drainage. However, loose silicone seton drainage should not be offered to patients as a treatment option to downgrade a complex fistula to a simple one or even have the hope to heal it.

Impact of Internal Anal Sphincter Division on Continence Disturbance in Female Patients

BACKGROUND

Few studies measured the pre- and postoperative anatomic and functional anal canal using 3-dimensional endoanal ultrasound and anal manometry and correlated sphincter division with fecal incontinence, severity, and function.

OBJECTIVE

To assess the incidence of fecal incontinence in patients who underwent internal anal sphincter division for anal fissure or intersphincteric anal fistula and correlate severity of symptoms with percentage of divided muscle, anatomical measurements, and anal pressures.

DESIGN

Prospective cohort study.

SETTINGS

Colorectal surgery unit, tertiary referral center.

PATIENTS

Patients underwent clinical assessment using the Cleveland Clinic Florida Fecal Incontinence score for severity of symptoms, manometry, and ultrasound.

MAIN OUTCOMES MEASURES

Ultrasound measurements of length, percentage, and angle of divided internal anal sphincter, anterior external anal sphincter, posterior external anal sphincter plus puborectalis, and gap lengths.

RESULTS

Sixty-three women (mean age, 44 years) were divided into 2 groups: 30 (48%) underwent fistulotomy for intersphincteric anal fistula and 33 (52%) underwent sphincterotomy for chronic anal fissure with high anal resting pressure. Forty-six percent experienced some measure of fecal incontinence after internal anal sphincter division. Incidence of fecal incontinence, severity of symptoms, and angle of the divided internal anal sphincter were similar between the groups. Length and percentage of the divided internal anal sphincter were significantly higher in the intersphincteric anal fistula. External anal sphincter and external anal sphincter plus puborectalis lengths were similar in both groups. Gap length was significantly longer in chronic anal fissures with high anal resting pressure.

LIMITATIONS

Single-institution, exclusion of males.

CONCLUSIONS

Fecal incontinence was reported in half of the patients who underwent internal anal sphincter division. Despite the greater length and percentage of internal anal sphincter division in patients who underwent fistulotomy, incidence and severity of fecal incontinence were similar in both groups. Three-dimensional endoanal ultrasound showed greater gap length in the sphincterotomy group, which may be functionally significant after the division of the shorter internal anal sphincter but with a similar impact on fecal incontinence in both groups.

IMPACTO DE LA DIVISIN DEL ESFNTER ANAL INTERNO EN LA ALTERACIN DE LA CONTINENCIA EN PACIENTES DE SEXO FEMENINO

ANTECEDENTES:Pocos estudios han medido el canal anal anatómico y funcional antes y después de la cirugía mediante ecografía endoanal tridimensional y manometría anal, y correlacionado la división del esfínter con la incontinencia fecal, la gravedad y la función.OBJETIVO:Evaluar la incidencia de incontinencia fecal en pacientes sometidos a división del esfínter anal interno por fisura anal o fístula anal interesfinteriana, y correlacionar la gravedad de los síntomas con el porcentaje de músculo dividido, las medidas anatómicas y las presiones anales.DISEÑO:Estudio de cohorte prospectivo.AJUSTE:Unidad de cirugía colorrectal, centro de referencia de tercer nivel.PACIENTES:Pacientes sometidos a una evaluación clínica utilizando la puntuación de incontinencia fecal de Cleveland Clinic Florida para la gravedad de los síntomas, la manometría y la ecografía.PRINCIPALES MEDIDAS DE RESULTADO:Mediciones por ultrasonido de la longitud, el porcentaje y el ángulo del esfínter anal interno dividido y el esfínter anal externo anterior, el esfínter anal externo posterior más el puborrectal y las longitudes del espacio.RESULTADOS:Sesenta y tres mujeres (edad media, 44 años) se dividieron en 2 grupos: 30 (48%) sometidos a fistulotomía por fístula anal interesfinteriana y 33 (52%) sometidos a esfinterotomía por fisura anal crónica con alta presión anal en reposo. El 46% experimentó algún grado de incontinencia fecal después de la división del esfínter anal interno. La incidencia de incontinencia fecal, la gravedad de los síntomas y el ángulo del esfínter anal interno dividido fueron similares entre los grupos. La longitud y el porcentaje del esfínter anal interno dividido fueron significativamente mayores en la fístula anal interesfinteriana. Las longitudes del esfínter anal externo y del esfínter anal externo más el puborrectal fueron similares en ambos grupos. La longitud del espacio fue significativamente mayor en la fisura anal crónica con alta presión anal en reposo.LIMITACIONES:Institución única, exclusión de varones.CONCLUSIÓN:La incontinencia fecal se reportó en la mitad de los pacientes sometidos a división del esfínter anal interno. A pesar de la mayor longitud y porcentaje de división del esfínter anal interno en los pacientes sometidos a fistulotomía, la incidencia y gravedad de la incontinencia fecal fue similar en ambos grupos. La ecografía endoanal tridimensional mostró una mayor longitud del espacio en el grupo de esfinterotomía, lo que puede ser funcionalmente significativo después de la división del esfínter anal interno más corto, pero con un impacto similar en la incontinencia fecal en ambos grupos. (Traducción-Dr. Fidel Ruiz Healy ).

Three-dimensional endoanal ultrasound to assess the validity of Goodsall's Rule and the Midline Rule in predicting the path of perianal fistula-in-ano and the location of the internal opening

BACKGROUND

Correct identification of the internal opening is essential in the management of perianal fistulae. The aim of this study was to assess the validity of Goodsall's Law and the Midline Rule in predicting the path of perianal fistula-in-ano and the location of the internal opening using 3-dimensional endoanal ultrasound.

METHODS

An observational study including patients diagnosed with fistula-in-ano, at our institution from January 2006 to December 2020 was performed. Location and distance from the anal verge of the external opening, internal opening, and the path of the fistulous tract were recorded during physical examination and endoanal ultrasound. Goodsall's and Midline rules were applied to all fistulae according to the location of the external opening. The location of the internal opening as predicted by either rule was then compared to the real location of the internal opening identified during endoanal ultrasound examination.

RESULTS

Nine hundred and nine patients [657 (72.3%) males, mean age 50.78 (49.84-51.72) years] were included. 665 (73.2%) of fistulae were transsphinteric. Concordance between predicted internal opening site and the true internal opening location was 0.601 (good match) for Goodsall's rule, and 0.416 (moderate match) for the Midline rule. Goodsall's rule proved to be more predictive in the anterior plane (p < 0.001). Both rules were more likely to make a correct diagnosis in posterior fistulae located 4.5-7.5 mm from the anal verge.

CONCLUSIONS

Both Midline and Goodsall's rules are highly predictive of the course of fistula tracts located in the posterior plane, and are lower for anterior located fistulae, female patients and when the external opening is located further from the anal verge.

Sphincter damage during fistulotomy for perianal fistulae and its relationship with faecal incontinence

Background

The length of sphincter which can be divided during fistulotomy for perianal fistula is unclear. The aim was to quantify sphincter damage during fistulotomy and determine the relationship between such damage with symptoms and severity of faecal incontinence and long-term quality of life (QOL).

Methods

A prospective cohort study was performed over a 2-year period. Patients with intersphincteric and mid to low transsphincteric perianal fistulas without risk factors for faecal incontinence were scheduled for fistulotomy. All patients underwent 3D endoanal ultrasound (3D-EAUS) pre-operatively and 8 weeks postoperatively. Measurements were taken of pre- and postoperative anal sphincter involvement and division. Anal continence was assessed using the Jorge-Wexner scale and QOL scores pre, 6 and 12 months postoperatively.

Results

Forty-nine patients were selected. A strong correlation between pre- and postoperative measurements was found p < 0.001. A median length of 41% of the external anal sphincter and 32% of the internal anal sphincter was divided during fistulotomy. Significant differences in mild symptoms of anal continence were found with increasing length of external anal sphincter division. But there was no significant deterioration in continence, soiling, or quality of life scores at the 1-year follow-up. Division of over two-thirds of the external anal sphincter was associated with the highest incontinence rates.

Conclusions

3D-EAUS is a valuable tool for quantifying the extent of sphincter involvement pre- and postoperatively. Post-fistulotomy faecal incontinence is mild and increases with increasing length of sphincter division but does not affect long-term quality of life.

Management of cryptoglandular fistula-in-ano among gastrointestinal surgeons in the Netherlands

BACKGROUND

Management of cryptoglandular fistula-in-ano (FIA) can be challenging. Despite Dutch and international guidelines determining optimal therapy is still quite difficult. The aim of this study was to report current practices in the management of cryptoglandular FIA among gastrointestinal surgeons in the Netherlands.

METHODS

Dutch surgeons and residents who are treating FIA regularly were sent a survey invitation by email. The survey was available online from September 19 to December 1 2019. The questionnaire consisted of 28 questions concerning diagnostic and surgical techniques in the treatment of intersphincteric and transsphincteric FIA.

RESULTS

In total, 147 (43%) surgeons responded and completed the survey. Magnetic resonance imaging was the preferred diagnostic imaging modality (97%) followed by the endo-anal ultrasound (12%). In case of a high FIA, 86% used a non-cutting seton. Most respondents removed a seton between 6 weeks and 3 months (n = 84, 58%). Fistulotomy was the procedure of preference in low transsphincteric (86%) and low intersphincteric FIA (92%). Mucosal advancement flap (MAF) and ligation of intersphincteric fistula tract (LIFT), with 78% and 46%, respectively, were the procedures that were applied most often in high transsphincteric FIA. In high intersphincteric FIA 67% performed a MAF and 33% a fistulotomy. Thirty-three percent of all respondents stated that they habitually closed the internal fistula opening, half of them used a Z-plasty. For debridement of the fistula tract the preferred method was curettage (78%).

CONCLUSIONS

Dutch gastrointestinal surgeons use various techniques in the management of FIA. Novel promising techniques should be investigated adequately in sufficient large trials to increase consensus. A core outcome measurement and a prospective international database would help in comparing results. Until then, treatment should be adjusted to the individual patient, governed by fistula characteristics and patient choice.

Rectal advancement flaps for the treatment of transphincteric perianal fistulas: a three-dimensional endoanal ultrasound and quality of life assessment

This study quantifies the damage to the internal anal sphincter (IAS) after a rectal mucosal advancement flap for a high transphincteric fistula in 16 patients using 3D-endoanal ultrasound. This was correlated with postoperative incontinence and quality of life scores. The median length of involved IAS preoperatively was 50 % (20-100) and 93.72 % for EAS (47.4-100 %). IAS division did not influence continence (p > 0.05). Continence deteriorated between the pre-, postoperative (p = 0.014) and six-month follow-up (p = 0.005), with no significant differences after one year (p > 0.05). The FIQOL score and SF-36 deteriorated initially, with recovery in all domains except for mental health after one year. Three fistulas recurred (18.75 %).

Puborectalis Muscle Involvement on Magnetic Resonance Imaging in Complex Fistula: A New Perspective on Diagnosis and Treatment

PURPOSE

According to recent studies, magnetic resonance imaging (MRI) assessment of complex fistulas provides a significant benefit compared to fistulography, computed tomography, and ultrasonography. The aim of this study was to describe the accuracy of MRI and the importance of identifying puborectalis muscle involvement on MRI in patients with complex fistula.

METHODS

All patients who were clinically diagnosed with 'complex' or showed multiple fistula tracts underwent fistula MRI. Eligible patients were consecutive patients who underwent fistula MRI between September 2018 and September 2019 at our hospital.

RESULTS

A total of 83 patients (74 males, 9 females; 116 tracts) were included in this study. The sensitivity and specificity of MRI in diagnosing fistula tracts were 94.8% and 98.2%, respectively. The sensitivity and specificity in identifying internal opening were 93.9% and 97.3%, respectively. Of the 35 patients with puborectalis muscle involvement in the MRI, 31 images of suprasphincteric-type patients on the Park's classification were classified. The patients of puborectalis involvement were divided into 2 groups according to the surgical procedure that was performed. There were 12 sphincter-saving procedures and 19 sphincter division procedures performed. Recurrence was seen in 2 patients in the sphincter-saving procedure group, while no case was seen in the sphincter division procedure group. Five complications were found in the sphincter division procedure group, of which 2 reported incontinence.

CONCLUSION

Fistula MRI is a highly accurate examination for evaluating complex fistulas, and the puborectalis muscle involvement findings are very important for diagnosis and treatment.

EFSUMB Recommendations for Gastrointestinal Ultrasound Part 3: Endorectal, Endoanal and Perineal Ultrasound

This article represents part 3 of the EFSUMB Recommendations and Guidelines for Gastrointestinal Ultrasound (GIUS). It provides an overview of the examination techniques recommended by experts in the field of endorectal/endoanal ultrasound (ERUS/EAUS), as well as perineal ultrasound (PNUS). The most important indications are rectal tumors and inflammatory diseases like fistula and abscesses in patients with or without inflammatory bowel disease (IBD). PNUS sometimes is more flexible and convenient compared to ERUS. However, the technique of ERUS is quite well established, especially for the staging of rectal cancer. EAUS also gained ground in the evaluation of perianal diseases like fistulas, abscesses and incontinence. For the staging of perirectal tumors, the use of PNUS in addition to conventional ERUS could be recommended. For the staging of anal carcinomas, PNUS can be a good option because of the higher resolution. Both ERUS and PNUS are considered excellent guidance methods for invasive interventions, such as the drainage of fluids or targeted biopsy of tissue lesions. For abscess detection and evaluation, contrast-enhanced ultrasound (CEUS) also helps in therapy planning.

LONG-TERM OUTCOMES OF LIGATION OF INTERSPHINCTERIC FISTULA TRACT FOR COMPLEX FISTULA-IN-ANO: MODIFIED OPERATIVE PROCEDURE EXPERIENCE

Background:

It is important but difficult to treat complex fistula-in-ano due to the high recurrent rate and following incontinence. Ligation of the intersphincteric fistula tract (LIFT), a novel surgical procedure with the advantage of avoiding anal incontinence, has a variable success rate of 57-94.4 %.

Aim:

To evaluate the long-term outcomes of modified LIFT operative procedure - ligation of intersphincteric fistula tract - to treat complex fistula-in-ano.

Methods:

Retrospective analysis of 62 cases of complex fistula-in-ano. The group was treated with the modified approach of LIFT (curved incision was made in the anal canal skin; purse-string suture was performed around the fistula; the residual fistulas were removed in a tunnel-based way) and had a follow-up time of more than one year. Patient´s preoperative general condition, postoperative efficacy and their anal function were compared.

Results:

The median age of the participants was 34, and 43 (69.4%) cases were male. Forty-one (66.1%) cases were of high transsphincteric fistula, four (6.5%) cases of high intrasphincter fistula, and 17 (27.4%) cases of anterior anal fistula in female. The median follow-up duration was 24.5 (range, 12-51) months. The success rate in the end of follow-up was 83.9% (52/62). The anorectal pressure and Cleveland Clinic Florida Fecal Incontinence (CCF-FI) evaluated three months before and after the operation did not find apparent changes.

Conclusions:

Compared with LIFT, the modified LIFT remarkably reduces postoperative failure and the recurrence rate of complex fistula with acceptable long-term outcomes.

CAN THREE-DIMENSIONAL ANORECTAL ULTRASONOGRAPHY BE INCLUDED AS A DIAGNOSTIC TOOL FOR THE ASSESSMENT OF ANAL FISTULA BEFORE AND AFTER SURGICAL TREATMENT?

BACKGROUND

There is no a clear knowledge concerning the division of any part of the anal sphincter complex and the effect of this procedure on the function of the anal canal during the treatment of perianal fistula.

OBJECTIVE

To evaluate the usefulness of 3D anorectal ultrasound in the assessment of anal fistula, quantifying the length of the sphincter muscle to be transected, selecting patients for different approaches and identifying healing, failure or recurrence after the surgical treatment.

METHODS

A prospective study included patients with primarily cryptogenic transsphincteric anal fistula assessed by fecal Incontinence score, tri-dimensional anorectal ultrasound and anal manometry before and after surgery. Based on 3D-AUS, patients with ≥50% external sphincter or external sphincter+puborectalis muscle involvement in males and ≥40% external sphincter or external sphincter+puborectalis muscle in females were referred for the ligation of the intersphincteric tract (LIFT) or seton placement and subsequent fistulotomy; and with <50% involvement in males and <40% in females were referred to one-stage fistulotomy. After surgery, the fibrosis (muscles divided) and residual muscles were measured and compared with the pre-operative.

RESULTS

A total of 73 patients was included. The indication for the LIFT was significantly higher in females (47%), one-stage fistulotomy was significantly higher in the males (46%) and similar in seton placement. The minor postoperative incontinence was identified in 31% of patients underwent sphincter divided and were similar in both genders. The 3D-AUS identified seven failed cases.

CONCLUSION

The 3D ultrasound was shown to be an effective method in the preoperative assessment of anal fistulas by quantifying the length of muscle to be divided, as the results were similar at the post-operative, providing a safe treatment approach according to the gender and percentage of muscle involvement. Additionally, 3D ultrasound successfully identified the healing tissue and the type of failure or recurrence.

Three-dimensional endoanal ultrasound is accurate and reproducible in determining type and height of anal fistulas

AIM

Surgical treatment of high anal fistulas is associated with the potential risk of faecal incontinence and recurrence. The primary aim of this study was to determine the accuracy of three-dimensional endoanal ultrasound (3D-EAUS) in the assessment of height and type of anal fistulas, compared to the intra-operative findings (gold standard). The secondary aim was to evaluate the inter-observer reproducibility of 3D-EAUS.

METHOD

The study design was a prospective analysis of retrospective data. 299 patients (202 men), mean age 45.3 years, who underwent surgery for anal fistulas, were included. All patients were preoperatively assessed by 3D-EAUS. Two readers independently reviewed the volumes to determine the type and height of fistulas. Sensitivity, specificity, positive and negative predictive values, proportion of agreements and Cohen's kappa coefficient (κ) were calculated for both examiners. Ultrasound findings were compared with intra-operative data (reference standard), evaluated blindly by the surgeons.

RESULTS

At surgery, 201 (67%) were transsphincteric, 49 (16%) suprasphincteric, 47 (16%) intersphincteric and two (1%) extrasphincteric fistulas. Intra-operatively, 177 (59%) were low and 122 (41%) high fistulas. The overall accuracy of 3D-EAUS was 91% for fistula type (271/299 fistulas: 97% transsphincteric, 100% intersphincteric, 57% suprasphincteric, 0% extrasphincteric) and 92% for fistula height (275/299 fistulas: 80% high and 100% low). Both readers reported very good agreement with surgery in the assessment of fistula type (proportion of agreement 0.88, κ = 0.89) and height (proportion of agreement 0.90, κ = 0.91).

CONCLUSIONS

3D-EAUS is an accurate and reproducible modality for the assessment of type and height of anal fistulas.

The outcome of fistulotomy for anal fistula at 1 year: a prospective multicentre French study

AIM

The study aimed to evaluate outcome at 1 year of one- and two-stage fistulotomy for anal fistula in a large group of patients.

METHOD

A prospective multicentre observational study was designed to include patients with anal fistula treated by one- or two-stage fistulotomy. Data were collected using a self-administered questionnaire before surgery, during healing and at 1 year after surgery.

RESULTS

Group A (133 patients) with a low anal fistula underwent a one-stage fistulotomy. The median Wexner scores before and after surgery were 1.0 (0-11) and 2.0 (0-18) (P = 0.032) and the median Vaizey scores were 2.0 (0-14) and 3.0 (0-21) (P = 0.055). The Wexner scores and percentage of patients before and after fistulotomy were as follows: 0-5: 88%, 86%; 6-10: 10.7%, 10.7%; 11-15: 1.0%, 2.6%; and 16-20: 0%, 2%. Eighty-seven per cent of the patients were satisfied. Group B (62 patients) underwent two-stage fistulotomy for a high transsphincteric fistula. The Wexner scores and percentage of patients before the first stage and 1 year after the second stage were as follows: 0-5: 86%, 66%; 6-10: 4.5%, 20%; 11-15: 9%, 11%; and 16-20: 0%, 2%. The median Wexner scores before the first stage and after the second stage were 1 (0-14) vs. 4 (0-19) (P < 0.001), and the median Vaizey scores were 1.5 (0-11) vs. 4 (0-20) (P < 0.001). Eighty-eight per cent of the patients were satisfied.

CONCLUSION

Low transsphincteric anal fistula can be treated by fistulotomy without clinically significant continence disturbance. Treating high transsphincteric anal fistulae with two-stage fistulotomy is followed by mild continence disturbance. Satisfaction rates were high.

Long-term follow-up after surgery for simple and complex cryptoglandular fistulas: fecal incontinence and impact on quality of life

BACKGROUND

Surgical management of cryptoglandular fistulas is a challenge because the consequences of anal surgery potentially include fecal incontinence and impaired quality of life.

OBJECTIVE

To assess factors associated with fecal incontinence after surgery for simple and complex cryptoglandular fistulas and to determine the impact of incontinence on quality of life.

DESIGN

The design is retrospective and cross-sectional.

SETTINGS

This study was conducted at an academic tertiary center and at a private center specializing in proctologic surgery.

PATIENTS

All patients who underwent preoperative endoanal ultrasound for cryptoglandular fistula between 2002 and 2012.

MAIN OUTCOME MEASURES

A questionnaire was sent out in October 2013 to evaluate incontinence (Wexner-score) and its impact on quality of life (FIQL). Variables tested for association were patient demographics, fistula type, number of incised abscesses (0, 1, >1), number of fistulotomies (0, 1, >1) and number of sphincter-sparing procedures (0, 1, >1).

RESULTS

Of the 141 patients participating, 116 (82%; 76 men, 40 women) returned all the questionnaires. Median follow-up from the first perianal fistula surgery was 7.8 years (range, 2.1-18.1 years). Thirty-nine patients (34%) experienced incontinence. Surgical fistulotomy, multiple abscess drainages and a high transsphincteric or suprasphincteric fistula tract were associated with incontinence. As compared to simple fistula (Wexner score, 1.2 [SD, 2.1]), incontinence was worse after surgery for complex fistula (Wexner score, 4.7 [SD, 6.2], p = 0.001), as were quality of life elements, including lifestyle (p = 0.030), depression (p = 0.077) and embarrassment (p < 0.001).

LIMITATIONS

Mainly retrospective design without a standardized treatment protocol.

CONCLUSION

Surgical fistulotomy is the strongest risk factor for fecal incontinence. The severity of incontinence increases with the complexity of the fistula, negatively influencing quality of life. Special attention should be paid to these patients so as to mitigate symptoms later in life. A shift to sphincter-sparing procedures appears warranted.

Role of tridimensional endoanal ultrasound (3D-EAUS) in the preoperative assessment of perianal sepsis

PURPOSE

The aim of this study was to evaluate the accuracy of tridimensional endoanal ultrasound (3D-EAUS) in the diagnosis of perianal sepsis comparing the results with the surgical findings, considered as reference standard.

METHODS

From January 2009 to January 2013, all the patients referred for the assessment and treatment of perianal sepsis with suspected anorectal origin were enrolled in the study. All patients gave informed written consent. Prior to surgery, all the patients underwent anamnestic evaluation, clinical examination, and unenhanced and H2O2-enhanced 3D-EAUS. Surgery was performed by a colorectal surgeon blinded to the 3D-EAUS results.

RESULTS

A total of 212 patients with suspected perianal suppurations were assessed during the study period. In 12 patients, the H2O2-enhanced 3D-EAUS was not performed, and so, they were excluded from the study. Very good agreement between 3D-EAUS and examination under anesthesia (EUA) in the classification of primary fistula tracts (kappa = 0.93) and in the identification of fistula internal opening (kappa = 0.97) was found. There was a good concordance (kappa = 0.71) between 3D-EAUS and surgery in the detection of fistula secondary extensions. The overall sensitivity and specificity of 3D-EAUS in the diagnosis of perianal sepsis were 98.3 and 91.3% respectively.

CONCLUSION

3D-EAUS is a safe and reliable technique in the assessment of perianal sepsis. It may assist the surgeon in delineating the fistula tract anatomy and in determining the origin of sepsis, supporting the preoperative planning of definitive and appropriate surgical therapy.

Methods for preoperative assessment of anal fistula

Anal fistula is one of the most common perianal diseases, and methods for its preoperative assessment are diverse. Traditional methods include physical examination, probing, Goodsall's law, methylene blue test, and so on. Although traditional methods play a role, their accuracy for complex anal fistulas is low. Therefore, their application must be combined with other methods. Fistulography fails to depict the relationship of the fistula to the sphincter complex, and computed tomography lacks specificity to distinguish between fistula and surrounding muscle tissue. Both methods are rarely used now. Magnetic resonance imaging and three-dimensional anorectal endosonography have become routine preoperative examinations and play an important role for guiding precise surgery. However, they also have their own shortcomings. In this paper, we will summarize a variety of methods for preoperative assessment of anal fistula.