Total mesorectal excision (TME) is a method for meticulous dissection of the mesorectal fascia along with all the lymph nodes through the avascular embryologic plane. It was introduced by Professor Heald in the 1980s to treat rectal cancer. Surgical approaches to rectal cancer have evolved over the years, overcoming the technical demands of the narrow pelvic cavity and aiming to establish a standardized approach [1]. Over the past few decades, laparoscopic and robot-assisted techniques have been rapidly adopted for colorectal surgery. Minimally invasive surgery (MIS) has gradually replaced laparotomy for colorectal surgery and has become popular recently. MIS has several well-recognized benefits, including fast recovery, relatively low postoperative pain and blood loss, short hospital stays, and low infection rates, without compromising oncologic outcomes [2]. Several surgeons have attempted single-incision laparoscopic surgery for colon cancer to maximize the benefits of MIS [3]. Recently, single-incision laparoscopic surgery for colon cancer has been shown to be safer than multiport laparoscopic surgery. However, rectal cancer has been excluded from most studies of single-incision laparoscopic surgery because of technical difficulties [4].

Robotic surgery has several advantages in the colorectal field, including its ability to provide stable three-dimensional views, flexible wrists and elbows, and a lack of hand tremors [5]. Previous systems for robotic single-incision surgery for colorectal cancer have been introduced; however, the EndoWrist system (Intuitive Surgical, Inc.) is unavailable in these previous systems, and they tend to have poor ergonomics [6,7].

Robotic transanal surgery, including transanal TME, using a previous robotic system has been proposed, and several studies have reported its feasibility and safety [8]. Moreover, many studies have recently reported the safety and feasibility of robotic single port (SP) systems for transanal TME [9]. However, few studies have investigated abdominal TME using the new SP system. In the present study, we aimed to report our initial experience with abdominal TME using the da Vinci SP system (Intuitive Surgical, Inc.) and determine its technical feasibility and safety.

From October 2021 to February 2022, a single surgeon performed surgeries on 15 consecutive patients with rectal cancer in our institution using the da Vinci SP system. Patients with relatively small and early-stage rectal cancer with no metastasis or previous abdominopelvic surgeries were included in the SP robotic surgery group. The docking time was defined as the time from the start of driving the robotic cart to complete port docking for the robot system All patients followed the enhanced recovery after surgery (ERAS) protocol [10].

Procedure

A standardized approach was used for all patients’ procedures. Under general endotracheal anesthesia, patients were placed in a modified lithotomy position, with the arms tucked along the body, and then patients’ bodies were tilted to the right, in reverse Trendelenburg positions. A single 4-cm transverse incision was made in the right lower quadrant, entering the peritoneal cavity, and a Uni-Port (Dalim) with a 25-mm port for the multichannel SP trocar, a 12-mm assistant port, and two 5-mm assistant ports were introduced. A 5 to 8-mm conventional laparoscopic port was placed in the right upper quadrant for the assistant cephalad to the Uni-Port (Fig. 1). The SP robot was positioned over the patient’s left side and docked at the Uni-Port. A camera was inserted at the bottom, a tooth retractor at the top (arm 2), monopolar curved scissors on the right (arm 3), and fenestrated bipolar forceps on the left (arm 1) of the multichannel SP trocar (Fig. 2).

Figure 1. Site of the uniport and 5 to 8-mm assistant port.

Figure 2. A 25-mm multichannel trocar with the instruments docked-in, with the camera at the bottom.

High ligation of the inferior mesenteric artery was performed with the help of an assistant who placed clips and applied an energy-sealing device (Fig. 3). Next, standard medial-to-lateral mesocolon sharp dissection was performed using the SP monopolar scissors through the right arm, dynamic countertraction was applied through the upper arm using the SP bipolar fenestrated forceps, and the SP round tooth retractor provided traction to lift the mesocolon upward through the right arm (Fig. 4).

Figure 3. (A) Isolating inferior mesenteric artery. (B) High ligation of the inferior mesenteric artery.

Figure 4. Medial-to-lateral mesocolon dissection.

A dissection was made toward the lower border of the pancreas, it divided the lateral peritoneal attachment near the splenic flexure and continued downward to release the rectum (Fig. 5). Thereafter, by using the relocated pedal, the robotic arm with the three instruments could be moved as a single unit toward the pelvis. TME was performed through the avascular plane of the mesorectal fascia (Fig. 6). With assistance, additional traction was achieved for better exposure of the TME plane. Rectal mobilization was initiated with a sharp dissection using the SP monopolar scissors, and the mesorectum was manipulated with the SP bipolar forceps to provide counterattraction. An SP grasper was used to push away other pelvic organs, and an assistant grasper was used to add traction to the rectum in dynamic motion as needed. The grasper was operated via the upper right quadrant port, with the suction tip in the left hand of one of the Uni-Port’s assistant ports. After achieving a sufficient distal margin, the SP system was uninstalled, and a laparoscopic linear stapler was introduced through the 12-mm port of the Uni-Port; this was used to transect the rectum under the laparoscopic view (Fig. 7). The specimen was retrieved through the Uni-Port in the right lower quadrant, and anastomosis was performed using the double stapling technique.

Figure 5. A lateral peritoneal attachment.

Figure 6. Total mesorectal excision performed. (A) Posterior rectal dissection. (B) Left rectal dissection. (C) Anterior rectal dissection. (D) Right rectal dissection.

Figure 7. Rectal resection by stapler.

In cases of very low-lying rectal cancer, intersphincteric resection with hand-sewn end-to-end coloanal anastomosis was performed. A protective ileostomy was created at the SP incision site at the surgeon’s discretion, and a pelvic Jackson-Pratt (JP) drain was placed through the assistant port (Fig. 8). See Supplementary Video 1.

Figure 8. Drain placed in an assistant port and ileostomy in the single port site.

A total of 15 SP rectal cancer surgeries were performed during the study period. Seven female (46.6%) and eight male patients (53.3%) with a median age of 61 years (range, 49–80 years) were enrolled in the study. The mean body mass index was 22.7 kg/m². The median distance from the anal verge to the lowest border of the tumor was 10 cm (range, 2–15 cm) (Table 1).

Table 1 . Patients demographics.

Variable	Data
No. of patients	15
Sex, male:female	8:07
Age (yr)	61 (49–80)
Average body mass index (kg/m2)	22.21 (18.4–29.4)
ASA PS classification
I	3 (20.0)
II	11 (73.3)
III	1 (6.7)
Tumor locationa) (cm)	10 (2–15)
Neoadjuvant chemoradiation	5 (33.3)
Operation type
SP LAR with/without ileostomy	12 (80.0)
SP ISR with ileostomy	3 (20.0)

Values are presented as number only, median (range), or number (%)..

ASA PS, American Society of Anesthesiologists Physical Status; SP, single port; LAR, low anterior resection; ISR, intersphincteric resection..

^a)Height from anal verge..

The median operative time was 186 minutes (range, 117–225 minutes), docking time was 4 minutes (range, 2–10 minutes), console time was 77.5 minutes (range, 46–99 minutes), and estimated blood loss was 20 mL (range, 20–50 mL). Patient preparation involved administering transversus abdominis plane block. None of the patients underwent open surgery (Table 2). Enhanced postoperative recovery protocols were followed for all patients [10]. One patient had a high-grade fever for 2 days, with microleakage demonstrated by abdominopelvic computed tomography, and was managed conservatively with antibiotics. The mean time for patients to resume an oral diet and until removal of the JP drain were 1.1 and 1.55 days, respectively, and the mean length of hospital stay was 8 ± 4 days (range, 4–12 days). No mortalities were reported (Table 2).

Table 2 . Perioperative outcomes.

Variable	Data (n = 15)
Operative time (min)	195 (160–230)
Docking time (min)	4 (2–10)
Console time (min)	80 (46–99)
Estimated blood loss (mL)	20 (20–50)
Length of stay (day)	5 (4–12)
Distal resection margin (cm)	2.5 (0.3–8.7)
No. of harvested lymph nodes	17 (9–24)
Tumor size (cm)	2.5 (0.1–5.7)
Complication	1 (6.7)

Values are presented as median (range) or number (%)..

Pathologic examination showed a mean distal resection margin of 3.52 cm (range, 0.3–8.7 cm), and the mean number of lymph nodes harvested was 16.5. Complete TME specimens with uninvolved circumferential resection margins were assessed for all patients.

Many studies have reported the benefits of laparoscopic colorectal surgery over the open approach [2], and several surgeons use fewer ports and only one incision to maximize the potential benefits of MIS and reduce port-related morbidities. Various studies have reported that single-incision laparoscopic colon surgery is technically feasible and safe, producing better cosmetic outcomes without compromising oncological outcomes [7–10]. Nevertheless, single-incision laparoscopic surgery is technically challenging because of instrumental collision and difficulty in introducing a linear stapler through an SP into the narrow concavity of the pelvis; therefore, it is mainly performed by expert surgeons. Several surgeons have attempted single-incision or reduced-port surgery using the da Vinci Xi system (Intuitive Surgical, Inc.); however, this does not eliminate the difficulty of configuring the arms because the camera and two semirigid robotic arms must be placed through an SP, causing limited range of motion and lack of effective traction and countertraction, while these two factors are essential for colorectal surgery. An additional port for the third robotic arm to maintain effective countertraction was proposed, and this demonstrated feasibility and safety. However, it did not improve the rigidity of the robotic arm in the previous system [7]. The new da Vinci SP robotic system functions has several new key features in comparison to the standard multiport da Vinci system including a single main arm that deploys the camera, and all three arms have new instruments that have been redesigned to include an extra joint that allows an internal working space (EndoWrist and endo-elbow). In addition to the patient cart, a new port to accommodate the three instruments at once of 26 mm in size and requires a disposable entry guide, through which the new flexible arms and camera can pass for docking. We also observed that the previously described Uni-Port, which contains a 25-mm transparent port for the multichannel SP trocar, is more versatile and helps the assistant change the position of the instruments when the SP boom is relocated. As it is a recent development in robotic surgery, reports on the feasibility and efficacy are limited.

Unlike single-incision laparoscopic surgery or reduced-port robotic surgery with a single incision at the umbilicus, we found that making a single incision in the right lower quadrant of the abdomen could increase the length and facilitate greater mobility of the relatively heavy, bulky, and long robotic arm in the new system. In addition, the new incision site achieved a better panoramic view of all abdominal quadrants and better visualization of the inferior mesenteric artery root, allowing secure and adequate oncological dissection.

By placing the assistant port 5 cm away from the robotic port and maintaining triangulation between both ports, internal and external clashes could be avoided. The assistant port is useful for passing sutures, clamps, clips, and suction and energy devices during a procedure, with sufficient length for the passage of instruments and access to target organs with high feasibility. The need for additional ports may change when additional instruments for the da Vinci SP system become available (Fig. 1).

Considering our experience, we believe that the da Vinci SP system has the following advantages: First, it has a fast docking time, a simple single docking procedure, and a noticeably quick learning curve, compared with those with the previous robotic system, as shown in Table 2. Second, there were fewer collisions between the robotic arms, because a single arm could be used to deliver three multi-joint robotic instruments that could be deployed and aligned internally and externally, with clear visualization of the tip of the instrument. In addition, a new multicamera mode with a cobra-like position was used to achieve clear visualization of posterior rectal dissection. Third, a single robotic arm can be used to reach multiple quadrants with a single docking placement. Fourth, better cosmetic results can be expected with a single incision.

Although the da Vinci SP system has several advantages, including potentially improved cosmesis, our initial experience helped us identify several drawbacks. First, the SP graspers tend to have weaker grip strength than those of the previous da Vinci systems, which would be a limitation in cases of bulky tumors or patients with obesity. Although such cases were not included in these initial surgeries, the feasibility of the da Vinci SP system in these categories needs to be explored. Second, surgeons require expert assistants to help them with suctioning, clipping, additional traction, and the use of advanced surgical energy-sealing devices. Finally, the da Vinci SP system does not have its own stapling system; however, this limitation can be resolved by using a conventional laparoscopic stapling system.

As the current study reported our initial experience with SP robotic rectal cancer surgery, the majority of the selected patients had low complexity diseases and low body mass indexes. In the future, we expect to transition to increasingly complex cases and sphincter-preserving procedures, as they are expected to benefit more from this system.

SP robotic transabdominal TME for rectal cancers is technically feasible and safe and shows acceptable short-term clinical and pathological outcomes. The potential of this system to effectively utilize a single-site approach for complex rectal procedures is promising although it has a significant learning curve to become familiar with some of the described techniques, including controlling the dynamic arm and various camera modes, Future prospective studies with large sample sizes and long follow-up periods, along with comparative studies of outcomes of the SP and multiport system are required.

Ethical statements

This study was reviewed and approved by the Research Ethics Board of The Catholic University of Korea, Seoul St. Mary’s Hospital (No. KC22RASI0187). Written informed consent was obtained from all patients.

Authors’ contributions

Conceptualization: All Authors

Data curation: WA, IKK

Formal analysis: WA, CSL

Writing–original draft: WA, YSL

Writing–review & editing: YSL

All authors read and approved the final manuscript.

Conflict of interest

All authors have no conflicts of interest to declare.

Funding/support

None.

Acknowledgments

The efforts and contributions of all participants in this study are gratefully acknowledged.

Data availability

The data presented in this study are available on request from the corresponding author.

Supplementary materials can be found via https://doi.org/10.7602/jmis.2023.26.4.208.