What is it?

If a suspicious lesion in the rectum might still be a benign polyp, a local resection (i.e. removal) may be opted for. In this case, the lump, including a limited margin, is removed through the anus. In case of smaller lesions, resection can be done immediately during the colonoscopy, but larger lesions sometimes require a surgical procedure through the anus. We call this a transanal endoscopic microsurgical resection or TEM. Based on microscopic examination of this large biopsy, a definitive diagnosis can be reached. If it proves to be a benign polyp after all, its total removal is usually sufficient and further treatment e.g. more far-reaching surgery, radiation or chemotherapy is not necessary.


Transanal endoscopic microsurgery or TEM is a procedure where a rigid access tube is inserted into the rectum through the anus under general anaesthetic. Through this tube, the rectum is inflated using carbon dioxide. Using the clear view provided by a 3D camera that has been inserted through the tube, the suspicious lesion can be completely removed using fine, long-handled instruments.

This technique allows for the full-thickness removal of the lesion from the rectal wall. This makes it possible for the pathologists performing the subsequent microscopic examinations to describe the depth of growth in the wall perfectly. After the resection (i.e. removal), the remaining defect in the wall of the rectum can be closed with sutures. This is not technically possible with larger wounds and, in that case, we leave the defect to heal spontaneously. To improve the view and reduce the risk of post-operative infections, a cleansing enema is usually administered before the procedure.

Possible complications

Post-operative discomfort or several complications may occur after a TEM:

Temporary weakness of the sphincter

As the rigid tube remains in place throughout the procedure, the sphincter is stretched for a long time. This sometimes results in temporary, relative weakness of the sphincter after the procedure which means that, in rare cases, you may unexpectedly leak gas. This discomfort is usually resolved very quickly.

Anal swelling

For the same reason, some patients have a sense of swelling of the anus similar to having haemorrhoids after the procedure. This pressure will also resolve naturally.


Severe pain does usually not occur, unless the resection was in the lower section of the rectum (the mucous membrane is a lot more sensitive in this area).

Blood loss

Because a wound is created on the inside of the rectum during this procedure, internal bleeding may occur. This is a possibility especially when the wound is left open. Discrete blood loss in the stools is a regular occurrence in the first few days and is no reason for concern.


If the internal wound was closed with sutured, an infection producing pus may develop beneath the sutures. The pus is generally evacuated spontaneously through the anus, but in exceptional cases, the abscess may spread into the abdominal cavity. In case of fever or stomache pain in the days after the procedure, the patient should contact us for further tests (such as blood tests andCT scan).


The subsequent approach after the transanal removal of a tumour depends mainly on the findings of the microscopic examinations. If the lesion was of no concern and the resection margin was sufficiently large, this procedure suffices in most cases. In that case, it is enough to monitor the wound through endoscopy. If a deeper, malignant tumour was diagnosed or if the resection (i.e. removal) turned out to be inadequate, further steps must be taken. Depending on the situation, the team of physicians may opt for an additional operation (removal of rectum) and/or radiation of the rectum.

Centres and specialist areas

General Surgery

Latest publication date: 05/02/2021
Supervising author: Dr Pletinckx Pieter