By Porf. Youssri GaweeshProfessor of colorectal surgery

Alexandria universityEgypt

The cryptoglandular pathogenesis This starts as an infection in the anal glands

at the base of the anal crypt. The abscess develops into the plane between internal and external sphincters and then extends to adjacent areas as the abscess expands

New anatomic conceptKurihara et al described the posterior anal space

with the complex fistula in a totally different way.

The posterior deep space (PDS): It lies in the posterior portion of the central anal region surrounded by the musculature. It is bounded by:Anteriorly the internal sphincter Supriorly inferior surface of the puborectalis the inferior and lateral borders are the anterior

surfaces of the external sphincter.

So the PDS lies within the deep part of the external sphincter in the intersphincteric space

The septum of the ischiorectal fossa (SIF) :

It is a septum made of connective tissue found in the ischiorectal fossa and it contains the inferior rectal vessels and nerves.

It extends from the Alcock’s canal to the anal canal.

It splits the ischiorectal fossa into two compartments, an upper one called the infralevator space (ILS), and the lower one named clinical ischiorectal space (CIS).

The inferior rectal vessels and nerves as they approach the anal canal in the (SIF), they divide to enter to the anal canal through holes between the puborectalis and the deep part of the external sphincter, and through holes between the deep and superficial parts of the external sphincter.

These holes present potential pathways for the extension of the pus from the PDS on either sides to either the ILS if passing high , or to the CIS if passing along the lower branches.

Hanley et al. assumed that the pus from the infected anal glands penetrate the internal sphincter, the longitudinal muscle layer and the external sphincter to reach the deep postanal space of Courtney from which pus can spread to the ischiorectal fossa.

this concept is dealing with a primary lesion situated trans-sphincteric while Kurihara et al. consider that the primary lesion is situated intersphincteric and only its extensions laterally are considered trans-sphincteric.

The posterior deep space (PDS) is different from Courtney’s space.

The Courtney’s space is extrasphincteric situated posterior to the superficial and the deep parts of the external sphincter whereas the PDS is situated within the deep part of the external sphincter.

Levator ani muscle

Puborectalis(anorectal

muscle ring)

Deep part

Superficial partSubcut. part

Of the ext. sph.

Alcok’s

canalILS

CIS

SIFInfralevat

or abscess

Ischiorectal

abscess

Supralevator

space

Coronal section showing Kurihara’s new anatomical concept

Levator ani(Ileococcygeu

s)Levator ani(puborectalis) 1ry lesion in

PDSDeep partSuperfici

al part

Subcut. part

External

sphincter

Midsagittal section showing Kurihara’s new anatomical concept

Investigations MRI Findings show 80-90% concordance with

operative findings when observing a primary tract course and secondary extensions.

Abdulsadek W.

Axial cut with extension to the inferalevator pocket

Coronal cut demonstrating the supralevator pocket that is situated intersphincterically

Saad M. Sh.

Unilateral approach

Another case

Midline approach for bilateral extension

Unilateral approach