- The rectoscope is put in place and a intraluminal pressure of approximately 10 mm Hg is being established.
- A suction is inserted to remove smoke after diathermy, fluids and possibly blood.
- With grips pliers in the left hand and dissecting instruments or needle holder in the right hand, resection and suture of the defect in the intestinal wall are performed.
- If the patient is fully relaxed with low intraabdominal pressure in order to distend the rectum and the polyp is not too big, a good visualization of the operation field is usually possible. If the polyp is growing very exophytic, and possibly has a large diameter (> 5.6 centimeters) the lumen will often be filled out after some dissection and this will complicate the overview.
TEM is technically difficult because of the small space in the rectoscope with three working intruments which easily collide with each other. When the rectoscope is mounted, there is a limited area of access to the rectal wall. It is therefore necessary to move and angle the rectoscope repeated times to reach the areas to be dissected or sutured.When everything functions optimally there is however good overview, and the different layers of the bowel wall are defined and it is possible to dissect submucosa or between the muscle layers in the muscularis propria or perirectal fat tissue (full wall resection).
Full wall resection is the quickest and most simple method and is preferred in the areas of the rectum where the entire wall can be removed. Distally, the external sphincter will be damaged and cranially on the anterior rectal wall, the abdominal cavity will be opened with a full wall resection. In these two areas, only a mucosal resection should be performed.
When operating for cancer a full wall resection is always the intention.