In what situations are transanal resection of rectal tumours performed?
Rectal polyps that are too large to be removed during colonoscopy
Colorectal polyps are potentially pre-cancerous and polyps that are too large to be removed during colonoscopy have to be removed surgically.
Selected early stage rectal cancers
The usual treatment of rectal cancer is surgical resection with an anterior resection or abdominoperineal resection. However, selected patients with early rectal cancers and favourable features on histology, may be treated with transanal removal. The advantages of this procedure are that it is a less major procedure than surgical resection and a stoma can be avoided.
How is transanal endoscopic resection performed?
During surgery, a special device that seals up the rectum and allows the maintenance of pneumo-rectum (where carbon dioxide is insufflated into the rectum) is inserted through the anus. This device also allows the insertion of instruments like a camera, grasping forceps and cutting devices.
The pneumo-rectum expands the rectum so that there is space for insertion and movement of the equipment. The high definition camera provides the surgeon with a magnified view of the tumour, and long instruments inserted through the device allows the surgeon to remove the tumour, much like how laparoscopic surgery is performed.
Traditionally, transanal resection of rectal tumours was performed open, without the use of any devices or cameras. However, studies have found that transanal endoscopic resection is associated with better resection margins (better clearance of the tumour cells). This is because of better visualization of the tumour with the camera, allowing surgery to be performed with improved accuracy.