postanal space fistula
TRANSCRIPT
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