**4. Intersphincteric rectal resection**

Sphincter preservation in patients with low rectal cancer is feasible reducing the distance between the tumor and the resection margin. In this way continence can be preserved, but still the oncological radicality of the procedure must be guaranteed.

A conservative procedure can be performed under the following condition:


When a free resection margin cannot be obtained without sphincter involvement, an abdomino-perineal resection must be performed.

In ultra-low rectal resections, it is possible to perform a manual coloanal anastomosis or proceed with the intersphincter resection, with partial or total removal of the internal sphincter. This technique aims to obtain appropriate longitudinal and radial margins [37], thanks to the presence of the Debray's reflex and the Parks mechanism, which would guarantee adequate continence [36].

The low rectal cancer can be classified in four groups according to Rullier [38]:


Type I patients are eligible for ultra-low anterior resection, type 2 for partial intersphinteric resection, type 3 for total intersphinteric resection and type 4 need abdomino-perineal resection. Postoperatively, only 50% of patients presents a good fecal continence; 11% suffers from severe fecal incontinence and 6% of patients

requires a definitive colonostomy due to severe postoperative fecal incontinence [38]. Performing a very low colorectal anastomosis can lead to anterior resection syndrome, characterized by involuntary loss of stool, urgency and multiple defecation, due to the loss of the rectal reservoir. Due to these disfunctions, some studies report that patients undergoing an ultra-low anterior resection present a lower quality of life than those undergoing abdominal-perineal amputation, despite the loss of the physiological possibility of defecating and the presence of a definitive ostomy. For these reasons, sphincter preservation procedures must be considered only for those patients who have an adequate sphincter function demonstrated by a manometric examination, and for those who accept a suboptimal functional result [37, 38].

There has been a progressive reduction in Mile's procedures, in favor of LAR which is currently the most used procedure even in cases of ultra-low lesions. Abdominalperineal amputation is preferred only when disease-free resection margins cannot be guaranteed without resecting the sphincters, or in case of their infiltration [39]. According to Rullier, an intersphinteric rectal resection is performed in two different surgical times: the intraabdominal and the transanal one. The former follows the usual steps of LAR. The transanal time starts with the exposure of the anal canal, using a retractor like Lone Star; for limiting the tumor seeding it is recommended to introduce a gauze into the rectum. The resection starts 1 cm below the tumor with a circular incision that transect the internal anal sphincter by both the mucosa and the muscular layer. Performing a partial or total resection of the internal sphincter depends on the level of the incision (on the dentate line or 1–2 centimeters below). The dissection continues upward between the two sphincters through an avascular plane and can be performed with scissors or an electric scalpel. The resection should start posteriorly and laterally where the external anal sphincter is more visible and proceeds anteriorly. The rectum is closed with a suture as soon as the upper edge of the anal ring is reached in order to avoid intraoperative tumor seeding; then dissection follows the levator ani fibers to reach the previous intrabdominal dissection or a transanal TME (TaTME) is performed [40].

### **4.1 Transanal total mesorectal excision**

In recent years, many efforts have been made to reduce surgical trauma and obtain better operative and postoperative results for patients, but despite the latest technological and surgical advances, rectal cancer surgery is still very complex especially in obese patients, with a narrow pelvis and low tumors. For these reasons, a new surgical approach has recently gained particular attention: the TaTME [41], which according to preliminary results of many centers, has proved to be safe and feasible [42]. The development of this technique resulted from the experience acquired through the different minimally invasive techniques in colorectal surgery: transanal endoscopic microsurgery (TEM) [43], transabdominal transanal (TATA) proctosigmoidectomy [44], transanal minimally invasive surgery (TAMIS) [45] and natural orifice transluminal endoscopic surgery (NOTES) [46, 47]. TaTME is a colorectal resection performed with laparoscopic instruments through a natural orifice: the anal canal [48]. TaTME can facilitate surgery in patients who require anterior resection for low and medium rectal tumors, where intraabdominal insertion of an endoscopic stapler could be limited by the anatomical conformation, such as in obese patients and in males with a narrow pelvis, allowing to achieve complete excision of the mesorectum with clean distal and circumferential resection margins [48, 49]. The TaTME technique developed by Lacie (Cecil Approach) involves the use of a double surgical

### *Robotic Rectal Resection for Rectal Cancer: State of the Art DOI: http://dx.doi.org/10.5772/intechopen.106199*

team, one for the abdominal time and one for the transanal time. Abdominal time coincides with the previously described LAR and involves mobilization of the splenic flexure and of the left colon, identification with section of the inferior mesenteric vein below the inferior margin of the pancreas, identification, and section of the inferior mesenteric artery at its origin. The transanal time begins when the inferior mesenteric artery is sectioned. A transanal surgical device (Buess Rectoscope or Gel Point Platform) is placed and the pneumorectum is performed, with a target pressure of 12–15 mmHg. A purse-string suture of the rectum is performed clockwise distal to the tumor, to prevent tumor spillage, from the anterior wall. The rectal wall is resected by a monopolar hook, with a full-thickness perpendicular transaction, following the holy plane, upwardly. The anterior and posterior planes are dissected at first, because easier to identify than the lateral ones; the lateral resection should be performed following the imaginary line that completes the circumference. Before the communication between transanal and abdominal field, a second purse string suture is performed in the free open edge of the distal stump; this suture will serve to tighten the stapler rod before the anastomosis. When the transanal surgical team is close to the peritoneal reflection, the two teams work together until the rendezvous is completed and the specimen is resected. The specimen can be extracted transanally if the dimension of the pelvis allows it, or transabdominally through a Pfannenstiel incision. The anastomosis could be a handsewn coloanal or a stappled end-to-end one, depending on the resulting stump length. The stapler anvil could be reinserted by the abdominal team if the specimen is extracted transabdominally or by the transanal team if extracted transanally. After tiding the distal purse-string suture around the circular stapler rod, the two parts can be connected, and it is possible to fire the stapler. At this point, the transanal device should be inserted again to verify the anastomosis. The side-to-end hand-sewn anastomosis is performed by pulling the colon wall near the distal rectal margin [50].
