Background: Coloanal anastomosis (CAA)/intersphincteric resection (ISR) is a promising method of sphincter-preserving surgery for very low rectal cancer. Recently, a robotic system has been attempted in CAA/ISR. By means of a robotic system, an excellent stereoscopic view may be obtained with high illumination, and adequate traction and countertraction can be easily performed in a narrow pelvis using the Endowrist function. During robotic CAA/ISR, although the robotic system is necessary to perform pelvic dissection that comes before the perianal approach, the huge robotic arms located in the low abdominal region could interfere with comfortable perianal dissection for the surgeon. Therefore, the robotic system has to be withdrawn and then set up again above the patient's abdomen, which is time-consuming. Moreover, this process also makes it difficult to maintain the aseptic circumstance of the robotic system. To address this problem, it is necessary to change the sequence of the procedure.
Methods: Patients with low rectal adenocarcinoma located within 6 cm above the anal verge were recruited and underwent robotic CAA/ISR. We performed the perianal approach first before docking the robotic system. In the transanal approach, manual dissection started at the level of the dentate line (for cases of CAA) or intersphincteric groove (for cases of ISR). The mucosa was stripped from the starting point to just above the levators. Robotic dissection was followed while maintaining pneumoperitoneum via packed gauzes in the anus. The surgical principles included high ligation of inferior mesenteric vessels and total mesorectal excision. Splenic flexure mobilization was selectively performed when the end of the remaining sigmoid colon could not reach the anal canal after the routine mobilization of the left colon side. After completion of total mesorectal excision, further dissection continued to the pelvic floor (Fig. 1). The puborectalis muscle sling was laterally exposed, and the anococcygeal ligament was noted on the posterior side of the anal canal. Intersphincteric dissection through the puborectalis ended at the intra-anal canal. Finally, the dissection plane could meet the perianal dissection plane. At this point, we could identify the gauze, which was packed via the perianal approach before beginning robotic dissection. The muscular rectal wall was divided by a cautery at the level of the puborectalis muscle by robotic arms. While performing the CAA/ISR, secure and meticulous dissection through the pelvic floor is important for oncological safety, which could be easily performed with the aid of robotic ergonomic Endowrist function and a magnified three-dimensional view even in a narrow pelvic cavity. Specimen extraction was done through the anus or additional minilaparotomy skin incision. In some cases, a planned ileostomy site was used as the minilaparotomy incision. For patients with bulky and heavy mesorectum, it is difficult and even dangerous to extract the specimen via the anus, which could induce traction injuries to the marginal vessels. Hand-sewn coloanal anastomosis was performed after removing the robotic cart from the operation field. The entire operative procedure is shown in the video. Early surgical outcomes, morbidity, and short-term follow-up data were extracted from a prospectively collected database.
Results: Robotic CAA/ISR for low rectal cancer was performed on 47 patients between August 2007 and December 2010. Forty-one patients underwent robotic CAA, and six patients underwent robotic ISR. There were 28 male and 19 female patients. The median age was 58 (range 32-86) years. The median body mass index was 23.3 (range 14.6-28.0) kg/m(2). Five patients (10.6%) had a history of abdominal surgery. According to American Society of Anesthesiology disease classification, 35 patients (74.5%) were class I, and 12 (25.5%) patients class II. The median distance between adenocarcinoma and the anal verge was 4 (range 1-6) cm. Preoperative chemoradiotherapy was provided to 19 patients (40.4%). There was no conversion to laparoscopic or open procedure. Operation time for robotic CAA/ISR was 360.9 ± 128.5 (mean ± standard deviation) min. For specimen retrieval, transanal extraction was performed in 23 cases (49%) and minilaparotomy was created for 24 cases (51%), including three cases of planned ileostomy site. Protective ileostomy was performed for 37 patients (78.7%). Blood loss was 158.0 ± 236.5 ml. The disease stage of the patients was as follows: stage 0, n = 1; stage I, n = 20; stage II, n = 5; stage III, n = 12; and pathologic complete response, n = 9. Tumor size was 2.7 ± 1.5 cm. The distal resection margin was 1.0 ± 1.2 cm. The circumferential resection margins were positive in 3 patients (6.4%). The number of retrieved lymph nodes was 9.8 ± 5.8. The first postoperative bowel movement was observed on day 2 (range, days 1-5). The median diet consumption began on day 3 (range, days 2-21). The median hospital stay was 9 (range 5-30) days. There were 10 complications in the early postoperative period (21.3%): 3 anastomotic leakages (6.4%), 1 wound infection (2.1%), 5 pelvic abscesses (10.6%), and 1 postoperative ileus (2.1%). During the short-term follow-up periods (median 21.3 months, range 3.5-40.7 months), one local recurrence, three distal metastases, and one combined recurrence were observed. Two-year disease-free survival rate was 83.7%.
Conclusions: Robotic CAA/ISR can be performed with good technical efficiency and acceptable morbidity. Further randomized, controlled studies assessing long-term survival, pelvic autonomic nerve function, and bowel function are needed before robotic CAA/ISR becomes widely accepted. Changing the sequence of the procedure, and thus performing the perianal approach before robotic dissection, may be a feasible method to avoid interference of the robotic system in the surgeon's moves using nonrobotic instruments while performing robotic CAA/ISR.