**6.2 Controversies surrounding extra-sphincteric fistula**

Park attributes extrasphincteric fistula to the following causes: secondary to a transphincteric fistula, trauma, specific anorectal disease and pelvic inflammation [5]. Eisenhammer's stated in both his initial series and final evaluation that extrasphincteric fistula was due to either iatrogenic probing or secondary causes such as pelvic sepsis, colonic diverticular diseases or inflammatory bowel disease [2, 6]. Garg's evaluation of more than 400 patients with anal fistula using MRI reported that there were no cases of extrasphincteric fistula in his series [12]. The most probable cause of extrasphincteric fistula: It is a combination of posterior high transphincteric fistula and high intersphincteric fistula situated posteriorly, resulting in both supra-levator collection and Infralevator collection. Incorrect drainage or probing of either can lead to a communication between the two collections across the levator ani [7]. Therefore, it is reasonable to conclude that extrasphincteric fistula does not fit into the natural pattern of cryptoglandular


*ΩπμAnterior high transphincteric pattern can present as bilateral horseshoe, anovulvar tract or unilateral horseshoe. Bilateral anterior horseshoe pattern tends to have a lower internal opening compared to unilateral anterior horseshoe pattern [2, 6]. However, no other studies reported similar findings. \**

*Infection occurs in the clinical ischiorectal space. Σ*

*Infection occurs in the infra-levator space.*

#### **Table 4.**

*Comparing current classification of natural patterns with Eisenhammer's updated description and classification in 1978 [6, 7].*

infection. Its finding should alert surgeons of possibility of previous erroneous surgery or secondary sepsis originating from pelvis/abdomen [6].
