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.