Anatomic characteristics of anal fistula on three-dimensional anorectal ultrasonography

Impact of Preoperative Three-Dimensional Endoanal Ultrasound on the Surgical Outcome of Primary Fistula in Ano. A Multi-Center Observational Study of 253 Patients

PURPOSE

To evaluate the impact of preoperative three-dimensional endoanal ultrasound (3D-EAUS) on the clinical outcome of anal fistula surgery.

METHODS

The research consisted of multi-center retrospective case-control study including 253 consecutive adult patients undergoing surgery for confirmed or suspected primary fistula in ano who had undergone preoperative 3D-EAUS evaluation between January 2011 and January 2021. Main outcome measures were the concordance (K value) between ultrasound results and surgery in the identification of fistulas internal openings, primary tracts and secondary extensions and the 6 and 12 months success rate in patients with concordant and discordant findings.

RESULTS

A good agreement in the identification of the main fistulas characteristics between ultrasound results and operative findings was found. A significant difference (P < .0001; Fisher's exact test) in the success rate was found between patients with concordant and discordant ultrasound results and operative findings in identification or location of internal opening. Particularly, all the 11 (4.8%) patients with discordant results experimented a failure of the surgical procedure at 6 months follow-up. At re-operation, the shift from discordant to concordant results was associated with an 81.8% 12 months success-rate.

CONCLUSION

The three-dimensional endoanal ultrasound preoperative evaluation may have a relevant impact on the outcome of a defined group of patients undergoing surgery for anal fistula, since the careful evaluation of ultrasound results could simplify the internal orifice intra-operative detection and improve the success rate.

Anatomical characteristics of anal fistula evaluated by three-dimensional anorectal ultrasonography: is there a correlation with Goodsall's theory?

Purpose We aimed to correlate the course of the anal fistula tract (T), location of the external opening (EO) and internal opening (IO) in anterior (A) and posterior (P) circumference using 3D-US according to Goodsall's rule.

Methods 151 patients with primary cryptoglandular Transsphincteric fistulas were examined with 3D-US and compared with surgical finding. The type of the T (straight or curved), EO and IO were identified and divided into 3 Groups: GI: EO and IO are located in a position; GII: EO and IO are located in P position and GIII: OE and OI are located in the opposite position. The findings were correlated with Goodsall's rule.

Results 74/151(49%) were included in GI, of them, 41 (55%) were male (33/44% had straight tract and 8/11% curved) and 33 (45%) female (15/20%-straight and 18/25%-curved). GII included 68 (45%), of them, 50 (74%) were male (39/57%-straight and 11/15%-curved) and 18 (26%) female (14/20%-straight and 04/8%-curved). GIII = 9 (6%) and all of them had curved tract. The overall concordance between 3D-US and surgical finding was 98% for tract and 96% for IO.

Conclusion The 3D-US findings correlate with the Goodsall's rule in transsphincteric fistulas located in the anterior circumference straight type, in male, while in females the distribution of curved and straight paths is similar. In the posterior circumference no correlation was observed in both the sexes.

Preoperative assessment of simple and complex anorectal fistulas: Tridimensional endoanal ultrasound? Magnetic resonance? Both?

PURPOSE

The purpose of the study is to evaluate the diagnostic value of tridimensional endoanal ultrasound (3D-EAUS) and magnetic resonance (MR) in the preoperative assessment of both simple and complex anorectal fistulas.

METHODS

All the patients referred for the treatment of anal fistulas were enrolled in this study and underwent, as preoperative assessment, anamnestic evaluation, clinical examination, and unenhanced and H2O2-enhanced 3D-EAUS and MR. The results of imaging evaluation were compared with surgical findings, considered as reference standard.

RESULTS

During the study period, 124 patients operated on for anal fistulas underwent complete preoperative imaging assessment. Perfect agreement between 3D-EAUS and surgery in the anal fistulas' severity grading was found (K = 1). The fistulas were classified as simple in 68/126 (53.9%) and complex in 58/126 (46.03%) cases, according to fistulas' Parks' classification and the most recent American Guidelines. In both simple and complex anal fistulas, 3D-EAUS did not show a significantly higher accuracy in the evaluation of internal openings, if compared with MR (P = 0.47; McNemar's Chi-square test). In the complex anal fistulas, MR showed a significantly higher accuracy in the evaluation of secondary extensions if compared with 3D-EAUS (P = 0.041; McNemar's Chi-square test), whereas in the simple anal fistulas, no significant difference was found.

CONCLUSION

In the preoperative work-up of patients with anorectal fistulas, 3D-EAUS may represent the first-line diagnostic tool. In cases of fistulas classified as complex by 3D-EAUS, MR may be indicated as adjunctive diagnostic imaging examination, to more carefully describe the fistulas' complete anatomy.

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.

Results of collagen plug occlusion of anal fistula: a multicentre study of 126 patients

AIM

The Biodesign(®) anal fistula plug was introduced as a means of obliterating the fistula tract and promoting healing through biocompatibility. The results demonstrated unexplained variations from good to bad. This report analysed the results of a retrospective multicentre study.

METHOD

All plug procedures performed in four Stockholm hospitals between June 2006 and June 2010 were identified and studied using a common protocol. The outcome after the first plug-insertion procedure was assessed by chart review performed a minimum of 8 months after plug insertion. Cox proportional-hazards models were used to assess the associations of various factors with fistula healing.

RESULTS

One-hundred and twenty-six patients (mean age 47 years) were deemed suitable for the plug procedure. Eighty-five per cent of fistulae were cryptoglandular, 64% of patients were male and a mean of 2.9 previous fistulae procedures had been performed. All patients, except four, had an indwelling seton at the time of the plug procedure, which was performed in accordance with previously established principles of day surgery. After a median of 13 months, 30 (24%) fistulae had closed with no discomfort or secretion reported. The outcome in the four hospitals varied from 13% to 33% with similar numbers of patients in each hospital. A success rate of 12% was observed for patients with anterior fistula compared with 32% for those with posterior tracks [hazard ratio (HR) for successful healing = 2.98; 95% CI: 1.01-8.78) and 41% for those with a lateral internal opening (HR = 3.76; 95% CI: 1.03-13.75). Age, sex and number of previous procedures were not associated with healing.

CONCLUSION

Four independent patient groups showed low success rates after the first plug-insertion procedure. Anterior fistulae were much less likely to heal compared with fistulae in other locations.

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.

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

PURPOSE

To quantify the longitudinal division of the internal anal sphincter (IAS) and external anal sphincter (EAS) after fistulotomy using three-dimensional endoanal ultrasound (3D-EAUS) and correlate the results with postoperative faecal incontinence.

METHODS

A prospective, consecutive study was performed from December 2008 to October 2010. All patients underwent 3D-EAUS before and 8 weeks after surgery. Thirty-six patients with simple perianal fistula were included. Patients with an intersphincteric or low transphincteric fistula (<66% sphincter involved) without risk factors for incontinence underwent fistulotomy. The outcome measures were the longitudinal extent of division of the IAS and EAS in relation to total sphincter length and continence (Jorge and Wexner scores).

RESULTS

One-year follow-up revealed a 0% recurrence rate. There was a strong correlation between preoperative 3D-EAUS measurement of fistula height with intraoperative and postoperative 3D-EAUS measurement of IAS and EAS division (p < 0.001). The relationship between the level of EAS division and faecal incontinence showed a significant difference in incontinence rates between fistulotomies limited to the lower two thirds of the EAS and those above this level. Five patients (13.9%) had worse anal continence after surgery, although this was mild in all patients (<3/20 Jorge and Wexner scale). There was no significant difference in continence scores before and after surgery (p > 0.05).

CONCLUSIONS

In patients without risk factors, division of the EAS during fistulotomy limited to the lower two thirds of the EAS is associated with excellent continence and cure rates.