**5.4 Standard Practice Task Force**

A practical and simple solution was created by Standard Practice Task Force in 2005, classified fistula-in-ano in just two categories-simple and complex [17]. The treatment of complex fistulas posed a high risk to anal continence and in simple fistulas, fistulotomy could be done safely without any risk of incontinence. The latter usually involved less than one-third of sphincter complex. Fistulotomy is not recommended in complex fistulas.

However, a study in 2017 showed that 32.1% (93/290) of complex fistulas were amenable to fistulotomy [12]. Simple and complex classification was shown to overestimate complexity of fistula. Furthermore, it was not particularly useful for clinicians in differentiating different types or patterns of complexity and determining the specific management.
