Mohammed Abu Hilal
The correct position of the pursestring is important.
One of the benefits of approaching the rectum from below is that the tumor height is exactly identified. If placed correctly, the upper border of the access channel of the flexible platform is hooked on the pelvic floor.
So in general the distance from the tumor to the the access channel is about the distance to the anorectal junction (ARJ). We call the distance between the ARJ and Tumor the ARJ-T.
However, the platform can be easily pulled down into the anal canal. We therefore recommend avoiding excessive manipulation of the access device and place it as low as possible for every case. One trick for accomplishing this is to release tension on the hooks of the Lonestar retractor. This drops the platform into a more natural position in the anal canal.
For all tumors located 4 or more centimeters above the ARJ (and thus above the edge of the access platform), the optimal position for the purse string is at about 3 cm.
For tumors between 2 and 4 cm above the ARJ (and access platform), place the purse string about 1 cm distal to the tumor. Later dissection started slightly below the purse string.
For lesions located below 2 cm from the ARJ, there is not enough space to perform a perfect purse string and a sleeve mucosectomy or intersphincteric dissection must be performed first.
So in general, when:
- ARJ - T > 4 cm, then the purse string is placed 3 cm from the ARJ
- ARJ - T = 2-4 cm, then the purse string is placed 1 cm distal to the tumor
- ARJ - T ARJ - T < 2 cm, then dissection is started without the platform ( sleeve mucosectomy or intersphincteric dissection is performed first, then purse string before introducing the platform)