**4. Surgical technique**

The essential steps for both TEM and TAMIS are similar. They include: operative field exposure, tumor excision, and defect closure.

The first step is the positioning of the rectoscope or of the SILS Port, then the lesion is identified, and the rectoscope or SILS port is fixed in place in the correct position. CO2 insufflation is then started to create pneumorectum until reaching an endoluminal pressure of 8–10 mmHg.

Once the lesion is identified, the line of excision is circumferentially marked by electrocautery with at least a 5–10 mm safety margin from the lesion, and dissection then starts at its caudal margin. Tumor resection can be performed by monopolar hook, ultrasonic instruments, or electrothermal bipolar energy devices. Dissection is carried around the lesion until the yellow adipose tissue of the mesorectum is identified and reached for a full-thickness resection. Full-thickness resection with adequate safety margins is performed routinely, with preservation of sphincter muscles (**Figure 7**). Full-thickness resection could be the cause of inadvertent entry into the peritoneal cavity. Should this occur, a laparoscope can be inserted into the abdominal cavity during TAMIS or in a TEM performed in lithotomy position, for better control of the peritoneal repair. If TEM is performed in the prone position, the patient will have to be turned in lithotomy position for diagnostic laparoscopy. After tumor removal, a suction-irrigation cannula is used for irrigation of the residual cavity and to check the hemostasis. Bleeding is controlled by monopolar or radiofrequency coagulation.

Following the tumor excision, the residual defect in the rectal wall can either be closed or be left opened. In the literature, no difference between these two techniques

**Figure 7.** *Step-by-step dissection technique for full-thickness excision and residual defect.*

is reported in terms of intraoperative results and final outcome [15]. Our personal preference is to close the defect, as previously reported [16, 17]. The closure can be performed with one or more interrupted or continuous sutures, with Lapraty (Ethicon®) preformed knots and with dedicated silver clips. In case of large defects, the closure can be carried out first by placing a single interrupted or figure of eight suture in the middle of the defect to draw the margins closer. At this stage, the endoluminal pressure can be reduced to facilitate suturing the margins of the defect with either single stitches or, preferably, with a running suture. The suture line should be closed without excessive tension not to cause tissue ischemia. Once the suture is completed, it is necessary to make sure that the rectal lumen has not been inadvertently closed. A suction-irrigation device is helpful in the final correct visualization of the suture.
