Challenging the predictive accuracy of goodsall's rule for anal fistulas

Abstract

To examine the predictive accuracy of Goodsall's rule, the records of 216 patients (155 men and 61 women) who underwent surgery for complete submuscular anal fistulas from 1982 to 1989 were retrospectively reviewed. In accordance with Goodsall's rule, 90 percent of 124 patients with an external opening posterior to the transverse anal line had anal fistulas tracking to the midline (87 percent men and 97 percent women). Only 49 percent of the 92 patients with an external opening anterior to the transverse anal line had anal fistulas that tracked in the radial fashion predicted by Goodsall (57 percent men and 31 percent women). Instead, 71 percent of these patients (62 percent men and 90 percent women) had anterior fistulas tracking to the midline. Overall, 81 percent (77 percent men and 93 percent women) of patients had complete submuscular anal fistulas that coursed to the midline (51 percent midline posterior and 30 percent midline anterior). In summary, Goodsall's rule is accurate only when applied to complete submuscular anal fistulas with posterior external anal openings. The rule is inaccurate in describing the course of complete submuscular anal fistulas with an anterior external opening. The men in this group had anal fistulas that defied Goodsall's rule in an unpredictable manner, whereas 90 percent of the women had fistulas tracking to a midline anterior origin.

Predictive accuracy of Goodsall’s rule for fistula-in-ano

“…To date, the studies done to assess the predictive accuracy of the Goodsall's rule have shown conflicting results [1,4,5]. According to a retrospective study of 216 patient records conducted in the 1980s, the predictive accuracy for fistulae with external openings posterior to the transverse anal line was 90% while for those with external openings anterior to the transverse anal line was 49% [1].…”

“…Recognition of both external and internal openings of the fistula tract is necessary for complete identification of the course of the tract. Identification of the external opening is obvious as the patient presents with a discharge through the external opening, but identification of the internal opening may not be straight forward [1]. Several classification systems exist to help clinicians to identify the path of the tract.…”

“…Goodsall's rule states that, if the external opening of the fistula is posterior to the transverse anal line, the fistula probably originates from the dorsal midline, whereas if the external opening is anterior, the tract probably extends directly to the nearest crypt [3]. Although it was universally accepted in the past, there has been conflicting data regarding the predictive accuracy of Goodsall's rule in recent times [1,[4][5][6]. Understanding the predictive accuracy of Goodsall's rule in various types of anal fistulae will be helpful for surgeons to locate the internal opening and define the fistula tract more precisely.…”

Rules for anal fistulas with scrotal extension

“…The popular Goodsall's rule for predicting the trajectory of anal fistulas is widely applied; however, in clinical practice, some cases are incompatible with this rule 1,2) . According to this rule, a transverse line is firstly drawn across the anus.…”

“…Goodsall's rule for predicting the trajectory of anal fistulas is popular; however, the long-tract anterior fistula, which may also include fistulas with scrotal extension, is an exception of this rule 1,2) . To the best of our knowledge, the rules applicable to anal fistulas with scrotal extension and the suitable operative treatment are yet to be described in detail.…”