Transanal Endoscopic Microsurgery (Wolf and Storz)
The anal sphincter is dilated after local anesthesia is injected, and the rectoscope is introduced into the rectum.
The lumen of the rectum is insufflated and the lesion identified.
Using a high-frequency energy device, clear margins are identified by marking dots. A margin of 5 mm is adequate for an adenoma, whereas a 10-mm margin is required for cancer.
Dissection begins at the lower edge of the lesion by circumcising the lower circumference. The tumor is folded upward so that the base is well exposed. Vessels are coagulated via diathermy at every step. Any spurting vessels can be grasped with forceps and their walls compressed before coagulation.
The plane of dissection is full thickness. In cases of cancer, the posterior surface and parts of the perirectal fat, including lymph nodes, can be resected with the specimen. Resection of mesorectum is also possible for posterior-wall tumors.
Dissection of the superior margins of the tumor can be difficult because of restricted vision; in such cases, dissection can be commenced from one marking dot to another, reducing the risk of leaving tumor behind.
After excision, it is important to note the healthy margins of macroscopic normal-looking mucosa.
Irrigation of the rectum with cancericidal agents such as povidone is believed to prevent implantation of cancer cells.
The defect is closed with transverse running sutures. Buess originally used polydioxanone sutures in a 5H needle, shortened to a maximum length of 10 cm. After a number of bites of the suture needle, the suture material is placed under tension and fixed with the aid of silver clips; knotting is difficult in this procedure. Semicircumferential defects require about three sutures, whereas complete segmental defects need as many as eight sutures.
Laparoscopic Gel Point Technique (Transanal Minimally Invasive Surgery)
The patient is positioned in either a lithotomy or prone jackknife position according to the location of the tumor/polyp.
Digital rectal examination is performed to localize the lesion.
After local anesthetic is injected, rectal access is achieved with the transanal access channel and introducer, which helps dilate the anal sphincter. After the access channel is inserted, it is sutured firmly to the skin with 2-0 silk sutures.
A gel seal cap, with the insufflation port and three 5-mm trocars already placed, is firmly fixed upon the access channel.
The rectal lumen is insufflated with CO2 with a pressure up to 12 mm Hg. A 30° endoscope, a tissue grasper, and an energy dissector are introduced through the trocars.
The lesion is visualized and its extent noted.
The margins of resection are then marked 1-1.5 cm circumferentially around the lesion with the help of an energy dissector.
The tumor/polyp is grasped, and full-thickness circumferential excision is commenced, with hemostasis achieved at every step. Perirectal fat should be visible beneath the lesion to confirm full-thickness excision. Larger vessels in the perirectal fat can be identified and coagulated or clipped.
After tumor excision, it is important to evaluate the healthy margins of macroscopic normal-looking mucosa.
Irrigation is performed as described above.
The defect is closed by using laparoscopic needle holders to place transverse running sutures (2-0 polyglactin sutures on a UR-6 needle). Owing to the restricted mobility of the needle holders inside the rectal tumor, some tricks are required to master the suturing technique. After five to eight bites of the needle, the suture material is kept under tension and fixed with clips or laparoscopic ties; knotting is difficult and unnecessary. The number of sutures depends on the size of the defect to be closed.
Complications
Complications are rare, but the following adverse results can occur:
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Pain, if dissection is closer to the dentate line
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Sense of fullness due to insufflation
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Gas explosion
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Trauma to the bowel wall or perforation - These are the most serious complications that can be avoided by surgical abilities and operative skills; if the peritoneum is entered during surgery, adequate closure of the defect is all that is required
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Infection
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Bleeding
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Urinary retention and urinary tract infection
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Vaginal mucosa injury
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Fecal incontinence
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Scars and strictures
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Failure of equipment
In experienced hands, complication rates are low, in the range of 4-7%.
