What does Goodsall's rule apply to?

Goodsall's rule is a principle used in assessing perianal fistulas, particularly those that occur in relation to the anal canal. The rule states that for a fistula that opens anteriorly (in front of the anal verge), the course of the fistula tends to run directly towards the anal canal. Conversely, if the fistula opens posteriorly (behind the anal verge), it will typically follow a curved path to enter the anal canal.

In this context, the rule is particularly relevant for fistulas located less than 3 cm from the anal verge, as they often conform to this predictable pattern. Understanding Goodsall's rule is instrumental when planning surgical intervention, as it informs the expected location and configuration of the fistulous tract. By identifying the type of opening of the fistula and its proximity to the anal verge, clinicians can better predict and manage the associated anatomy, which is crucial for successful treatment and minimizing the risk of recurrence.

Therefore, the application of Goodsall's rule to fistulas less than 3 cm from the anal verge highlights its importance in surgical planning and teaches the fundamental anatomy relevant to anal fistulas.