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

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.