Accuracy prediction of Goodsall's rule for anal fistulas of crypotogladular origin, is still standing?

Background

Treatment of anal fistulas is still a challenging task because of high recurrence and risk of incontinence. Identification of internal fistula opening is paramount for successful treatment. Goodsall's rule is commonly used to predict the course of fistula and internal opening. However, its accuracy has been questioned by many investigators and its role became a controversial topic.

Method

This is a case series prospective study in which 320 consecutive patients with anal fistula with Mean age 48.9± 6 years ages (ranges from 16 to 64 years) and mean body mass index 24.8± 5.5 average 18.5-30.6) were enroled. Goodsall's rule was applied to all fistulas according to the site of external fistula opening. Location of internal fistula opening as suggested by Goodsall's rule then compared to the exact location of internal opening identified by perineal or pelvic MRI and intraoperative findings. to assess the accuracy and positive predictive value of the Goodsall's rule in predicting the internal opening of the tract.

Results

The overall accuracy rate, positive predictive value (PPV), sensitivity and specificity of Goodsall's rule in this study were 74.75%, 77.1, 74.5, and 72.05, respectively. The accuracy in predicting the internal fistula opening was 52.4% in anterior tracts and 73% in posterior tracts. Goodsall's rule was found to be more accurate in posterior fistulas than anterior fistulas and in short superficial fistulas rather than in long and high fistulas.

Conclusion

Goodsall's rule was accurate in 74.75% of anal fistulas. It was more accurate for posterior long fistulas and anterior short and superficial fistulas. Patients with long (>3 cm) anterior fistulas defied Goodsall's rule when they found to have fistulas tracking to a midline anterior origin. Further, short posterior fistulas were found to open more commonly in a direct radial course rather to midline posteriorly.

Preoperative magnetic resonance imaging of anal fistulas with scrotal extension: a retrospective study

Introduction

This study aimed to elucidate the magnetic resonance (MR) characteristics of anal fistulas extending to the scrotum, and the applicable rules, and to correlate MR features with surgical findings.

Methods

We conducted a retrospective study in 150 consecutive patients with anal fistulas extending into the scrotum, who were diagnosed and underwent surgery at University Medical Center Ho Chi Minh City between January 2017 and April 2022. MR findings were evaluated and compared with surgical findings using Cohens kappa coefficient (k) with a 95% confidence interval.

Results

150 patients (mean age 37.6 ± 10.9 years) with 166 fistulas, including 150 anal fistulas with scrotal extension. Most fistulas were low transsphincteric (80.0%, 120/150 patients). There was a strong agreement for primary tract classification and detecting the location of internal openings between MRI and surgical findings with k = 0.83 (0.780.87) and k = 0.89 (0.85 0.93) (p<0.001), respectively. There is a significant correlation between the location of internal openings and the type of fistula (p<0.05). Low transsphincteric fistulas were predominant in the anterior group (103/122 patients vs. 10/19 patients), while in the posterior group, it was more common in the high transsphincteric fistulas (7/19 patients vs. 14/122 patients), and the intersphincteric fistulas (1/19 patients vs. 5/122 patients); and the suprasphincteric fistulas were only seen in the posterior group (1 patient).

Conclusion

Anal fistulas with scrotal extension are exceptions to Goodsalls rule. Albeit long-tract fistulas, most are low transsphincteric and have anterior internal openings.