Endorobotic submucosal dissection of rectal lesions using the single port robot DaVinci‐SP: initial experience of the first 10 cases

Endoluminal surgery is increasingly recognized as a mode of treatment for colorectal neoplasms with the latest robotic single port platform Da Vinci‐SP (Intuitive Surgical, Sunnyvale) facilitating submucosal dissection of benign rectal neoplasm.


Introduction
Non-malignant polyps (NMP) account for 25% of all elective colectomies and proctectomies in the United States, with the incidence of surgery rising. 1 Colectomies and proctectomies for NMP are associated with a significant risk of complications, with one study reporting morbidity of 21% and mortality of 0.5%, with only 3.3% of final pathologies showing malignancy. 2 Thus, advanced endoscopy, lately named endoluminal surgery, has recently been suggested as an alternative treatment.
Endoluminal surgery, including endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), and hybrid ESD, has emerged as a treatment modality for larger (>2 cm) mucosal neoplasms that are not amenable to standard endoscopic removal techniques.The technical difficulty and the steep learning curve have limited the widespread utilization of endoluminal surgery in the West.One study found that the en bloc resection was only achieved in 76% of the first 50 ESD performed, which increased to 98% after 250 ESD. 3 The current endoluminal surgery platforms have some technical limitations.The result of lack of endoscopic stability leads to rapid, jerky movements during dissection.The standard colonoscope also has only one working channel for dissection, which does not allow traction/counter-traction and triangulation of planes required for accurate surgical dissection.For distal colonic/rectal NMP, the transanal robotic surgery can potentially overcome these limitations to allow for more precise and controlled dissection.There have been reports of multiport Da Vinci Xi (Intuitive Surgical, Sunnyvale, CA) systems used for distal colonic/rectal dissections with reported complete surgical excision with a negative margin of 94.8%-97%. 4,5The Davinci Xi system is a multiport system that is inserted transanally through the GelPoint ® Path Transanal Access Platform (Applied Medical, Rancho Santa Margarita, CA).The latest advance in robotic surgery has been the Da Vinci Single Port(SP) System ® (Intuitive Surgical, Sunnyvale, CA), which has a single port through which two or three working arms as well a camera can be inserted.The single port, as compared to multiport, means less crowding and more mobility during dissection in a confined space of the rectum/distal colon.][8] Marks et al. showed feasibility of Da Vinci-SP system in transanal surgery by performing two transanal minimally invasive surgery (TAMIS) and two transanal total mesorectal excision (TaTME). 9,10he aim of this study is to present our initial experience of transanal endorobotic submucosal dissection using the latest Da Vinci SP system.

Methodology
A single institution, IRB-approved prospectively collected database was retrospectively analysed.The first 10 patients undergoing endorobotic submucosal dissection with the Da Vinci SP system between 2020 and 2021 at The Cleveland Clinic (main campus, Ohio) were analysed.All surgeries were performed by a single surgeon (EG).All patients with colorectal mucosal neoplasms located within 24 cm from the anal verge were included in the study after informed consent.Patient demographic information, including age,  gender, and body mass index (BMI), was collected for analysis.Information on the total operative time, distance from the anal verge, size of the lesion, the margin of clearance, and pathological diagnosis were also analysed.

Preoperative workup
All patients undergoing evaluation for endorobotic submucosal dissection with Da Vinci SP underwent preoperative colonoscopy by a board-certified gastroenterologist or surgeon.At the time of colonoscopy, anatomic measurements, including size and distance from the anal verge, were measured, and tissue biopsies were taken.Patients with biopsies showing adenocarcinoma were not considered candidates for endorobotic submucosal dissection and were excluded from the study.

Operative intervention
All patients were given a preoperative routine oral mechanical bowel preparation the day before surgery.The patient received prophylactic subcutaneous heparin and intravenous antibiotics (cefazolin and metronidazole) as per institution protocol.Patients were placed in a modified lithotomy position and placed in reverse Trendelenberg position (head down).
After digital rectal examination, the access channel of the GelPoint Path ® (Applied Medical, Rancho Santa Margarita, CA) was inserted transanally and secured in place by placing two holding sutures onto the skin.Through the cap of the GelPoint, the Da Vinci SP port, an AirSeal ® port (Conmed, Largo, FL), and a suction/irrigator was placed (Fig. 1).The location of the camera within the Da Vinci SP port was determined by the location of the polyp (Fig. 2).For lesions very close to or at level of the dentate line, the distal end of the polyp was lifted transanally, and then the access channel of the GelPoint was inserted.The Da Vinci SP robot was docked from the left side of the patient (Fig. 3).After achieving pneumorectum, submucosal injection with a lifting agent (ORISE™ Gel Submucosal Lifting Agent, Boston Scientific, Marlboroug, MA) was performed (Fig. 4).The endoscopic injection needle was inserted through the AirSeal Port, and the needle was guided in place by the robotic arms.The suction/irrigator was controlled by a foot pump and positioned in place by a robotic arm holding onto a suture placed at the tip of the suction/irrigator (Fig. 5).Dissection was performed in the submucosal plane with the flexibility of the robotic arms allowing for traction to be applied in different directions (Fig. 6).The ESD defect was sutured closed using barbed knotless sutures V-Loc™(Medtronic, MN).After the completion of dissection, the robot was undocked, specimen was extracted and laid out (Fig. 7).
All dissections were en bloc, and there was no need for additional instrumentation or re-docking.We observed no intraoperative complication, morbidity, or mortality.All patients started a normal diet after the procedure and were discharged on the same day.There were two complications within 30 days of the procedure.One patient receiving anticoagulation (clopidogrel) had late-onset bleeding on the 10th day after surgery.On readmission, a colonoscopy was performed; however, no active bleeding was identified (Clavien Dindo Grade II).Another patient had urinary retention after the procedure.A Foley catheter was inserted, which was removed prior to discharge (Clavien Dindo Grade I).Pathology of the specimens revealed two adenocarcinomas with pT1, six tubulovillous adenomas, one tubular adenoma, and one sessile serrated adenoma.All specimen margins were clear.One patient with adenocarcinoma was offered surgery (T1 with perineural invasion) however declined.The patient underwent imaging (MRI) and endoscopic surveillance, with no recurrence seen after 21 months.Another patient with high grade T1 adenocarcinoma wit lymphovascular invasion underwent robotic  abdominoperineal resection with the final pathology pT1N1 (1/19 lymph nodes).
There was no recurrence in all other patients during the median follow-up of 6 months (range: 4-16 months).

Discussion
This study presents our initial experience with endorobotic submucosal dissection using Da Vinci SP for rectal mucosal neoplasms.Our total operative time of 91 min and specimen size of 42.3 mm is comparable to the endorobotic surgeries performed using the Xi system. 4,5We have been able to achieve en-bloc resections and clear margins in all patients.There were only two minor complications, including urinary retention and late bleeding per rectum.
In comparison to the standard colonoscopic ESD, transanal endoscopic microsurgery (TEMS), transanal minimally invasive surgery (TAMIS), the single port Da Vinci SP system has multiple advantages.Colonoscopic ESD is technically difficult, with rate of incomplete resection of 4.1% and perforation of 5.6%. 11he movement of the 'working-arm' in left/right, up/right axis simultaneous moves the camera at the same time as it requires the movement of the colonoscope itself.Colonoscopic ESD also usually has one working arm, therefore distal caps and endoclips as 'clip-flaps' to act as retractor to aid in dissection. 11,12Also, the movement of the colonoscope is comparatively less smooth and often in jerky, staccato-like motion which can result in overshooting of dissection.The TEMS has a rigid laparoscopic platform, which means the operator is unable to view the operation from different angles without detaching the entire platform.The TAMIS allows the assistant to move the laparoscope to view from different angles and also use of 3D laparoscopic camera.The advantage of DaVinci SP's system over the TEMS and TAMIS is that the surgeon is able to move the camera freely.The 3D view also allows better depth perception and the images may be magnified for more precise dissection. 13The three working arms of the DaVinci SP allows for simultaneous dissection, retraction/counter-traction as well as use of suction.Whilst use of all three working arms are not always necessary, for large bulky lesions two arms may be used to retract two points of the raised flap of lesion.In comparison to the multiport Da Vinci-Xi or Si systems, the single port of DaVinci-SP reduces clashing in the small space of rectal lumen.A limitation of robotic ESD is that it can only be performed for distal colonic/rectal lesions.There are new upcoming robotic endoluminal systems such as ColubrisMX-ELS™ (ENDOQUEST, Houston) that has been described in the literature which may help facilitate dissection of more proximal colonic lesions. 14,15The access channel of the GelPoint is such that the proximal flange must be above the anal sphincter.Therefore, rectal lesions which are very close to the anal verge or the anal sphincter would not be amenable to be removed  with this method.In our case series, the closet lesion was 2 cm from the anal verge.For lesions very close to or at level of the dentate line, we lifted the distal end of the polyps transanally before inserting the access port of the GelPoint.Another disadvantage of DaVinci SP system is that it does not come with a suction/irrigation system, however we have utilized a standard laparoscopic suction/irrigator.

Conclusions
Endorobotic submucosal dissection using the Da Vinci SP is promising and, in our experience, safe and feasible for distal colonic/ rectal mucosal neoplasms.

Fig. 2 .
Fig. 2. Position of the camera and the robotic instruments within the Da Vinci SP single port channel.

Fig. 3 .
Fig. 3.The Da Vinci SP robot is docked from the left side of the patient.

Fig. 4 .
Fig. 4. The submucosal injection is performed with a lifting agent.

Fig. 5 .
Fig. 5.A knot was tied around the end of the suction irrigator.This allows the robotic arm to grab and manoeuvre the suction/irrigator into the operative field.

Fig. 6 .
Fig. 6.Dissection is performed in the submucosal plane, with one robotic arm providing traction.After extensive dissection, the mucosal defect may be closed by suturing.