Surgical Robot-Assisted Transanal Specimen Extraction Radical Sigmoidectomy Without an Auxiliary Abdominal Incision

Summary

Robot-assisted natural orifice specimen extraction surgery is a minimally invasive technique that combines robotic precision with natural orifice specimen extraction. A 67-year-old patient successfully underwent the procedure in 290 min, with minimal bleeding and no residual cancer. This approach minimized abdominal trauma, reduced complications, and enabled a quick recovery.

Abstract

Robot-assisted natural orifice specimen extraction surgery (NOSES) for sigmoid colon cancer represents an innovative, minimally invasive surgical technique that integrates the benefits of minimally invasive surgery with natural orifice specimen extraction. In this study, a 67-year-old male patient diagnosed with sigmoid colon cancer underwent Kangduo surgical robot-assisted NOSES, with a total operative time of 290 min and an estimated intraoperative blood loss of 50 mL. The procedure involved robotic-assisted radical resection of the sigmoid colon, regional lymphadenectomy, and specimen extraction through a natural orifice. Postoperative histopathological analysis confirmed the absence of residual malignancy in the resected sigmoid colon, while 12 pericolic lymph nodes exhibited reactive hyperplasia. Both the proximal and distal surgical margins were negative for malignancy. The patient had an uneventful recovery and was discharged on postoperative day 7. The precision and flexibility of the robotic system facilitated NOSES by minimizing abdominal wall trauma, reducing postoperative complications, and shortening recovery time. This finding indicates that robot-assisted NOSES is a safe and feasible approach for the surgical treatment of sigmoid colon cancer, though further clinical experience and long-term follow-up are required to comprehensively assess its efficacy.

Introduction

Natural Orifice Specimen Extraction Surgery (NOSES) is an innovative advancement in minimally invasive surgical techniques, offering the advantage of avoiding abdominal wall incisions for specimen extraction. This approach integrates the benefits of laparoscopic or robotic surgery with specimen extraction through natural orifices, thereby reducing surgical trauma, minimizing postoperative pain, and facilitating faster recovery¹.

Robot-assisted surgery has revolutionized the field of minimally invasive procedures by enhancing precision, dexterity, and visualization through robotic systems². The integration of surgical robotics further optimizes surgical outcomes by enabling more intricate dissection and suturing, particularly in anatomically challenging areas such as the narrow pelvis³. Notably, robotic-assisted surgery is associated with a reduced risk of conversion to open surgery in obese and morbidly obese patients compared to conventional laparoscopic approaches⁴.

Robot-assisted NOSES is emerging as a feasible and safe alternative to conventional laparoscopic or open surgery for colorectal cancer treatment. By eliminating the need for auxiliary incisions for specimen extraction, NOSES can potentially reduce postoperative complications, shorten hospital stays, and enhance cosmetic outcomes without compromising oncological safety⁵. This protocol herein presents a surgical approach involving robot-assisted transanal specimen extraction radical sigmoidectomy without an auxiliary abdominal incision (NOSES-IV).

Structural design of the robot
The Surgical Robot system consists of a surgeon control console, a three-arm patient cart, and a vision cart (Figure 1). The surgeon console is an open-vision system equipped with a foot clutch for switching between systems. The patient cart features two surgical arms and a camera arm. For safety, the system automatically locks the robotic arms of the patient cart when the sensor on the main manipulator detects that the hand has disengaged from the device. An additional trocar is also placed for the assistant. The visual cart is employed by the assistant surgeon to observe the surgical field. During the operation, the surgeon sits at the open surgeon's console with an upright neck posture, while the three-arm patient cart is positioned on the patient's left side.

CASE PRESENTATION:

The patient underwent endoscopic submucosal dissection (ESD) following the identification of a polypoid lesion in the sigmoid colon during a colonoscopy, which had been noted 1 month prior to admission. Postoperative histopathological examination revealed a laterally spreading tumor in the sigmoid colon with malignant transformation, classified as moderately differentiated adenocarcinoma. The tumor measured 0.8 cm in total diameter, with the cancerous component occupying 0.6 cm. Histological examination confirmed submucosal invasion, with an infiltration depth exceeding 1,000 µm, necessitating additional surgical intervention.

The patient's medical history included hypertension, diabetes, and brain infarction. The patient, aged 67, had a body mass index (BMI) of 25.7 and showed no signs of anemia. Physical examination revealed no enlargement of the superficial lymph nodes, and abdominal assessment showed no abnormal findings. Additionally, digital rectal examination revealed no masses.

Accessory examinations were conducted, revealing no significant abnormalities in blood routine analysis, biochemical profiling, blood coagulation, or CA19-9 levels (32.13 U/mL). However, CEA (7.07 ng/mL) was elevated. Consequently, a multidisciplinary team decided to proceed with robot-assisted NOSES.

Indications and contraindications of NOSES IV:
Indications
The tumor is located in the upper rectum, rectosigmoid colon, and distal sigmoid colon; the circumferential diameter of the tumor should be <3 cm; and the tumor should not invade the serosa.

Contraindications
A large tumor that poses a challenge to extract a specimen from the anus; the mesorectum is too thick to be extracted from the anus; and body habitus (BMI > 35 kg/m²).

Protocol

This protocol was performed in line with the principles of the Declaration of Helsinki. The protocol followed the guidelines of the local institution's human research ethics committee and was approved by the local institutional review board (2022-45, September 29, 2022). The patient provided informed consent to participate in the study and for the publication of their anonymized case details and images.

1. Patient positioning and trocar layout

1. Position the patient in a modified lithotomy position with the head tilted 15-30° lower than the feet to achieve the Trendelenburg position. Perform the sterile preparation and check the availability of instruments.
2. Position the robotic platform on the patient's left side and use three mechanical arms during the surgical procedure. To prevent unintended contact, engage the clutch on the surgeon's console to unlock the mechanical arms.
   NOTE: Do not adjust the patient's position or the operating bed after effectively connecting the robotic arms.
3. Establish pneumoperitoneum through Trocar C with a Veress needle connected to the insufflator, setting the pressure to 12 mmHg. Remove the Veress needle, transfer the insufflation tube to a 12 mm trocar (Trocar A1), and insert the trocar as a temporary camera port.
4. Insert the robotic endoscope through the camera port and perform a diagnostic laparoscopy. Have the assistant surgeon hold the robotic endoscope to confirm adhesion status, exclude peritoneum metastasis, and evaluate operative feasibility.
5. Under the guidance of the endoscope, insert the remaining trocars as follows (Figure 2).
   1. Insert Trocar C for the 30° camera of the robot to connect the mechanical arm (8 mm): 2 cm above the umbilicus and 1 cm to the right.
   2. Insert Trocar R1 for the operating surgeon to connect the mechanical arm (8 mm): On the intersection of the trocar C level and the left midclavicular line.
   3. Insert Trocar R2 for the operating surgeon to connect the mechanical arm (8 mm): At a point 1/3 of the distance from the umbilicus to the right anterior superior iliac spine.
   4. Insert Trocar A1 for the first assistant surgeon (12 mm): On the intersection of the trocar C level and the right midclavicular line.
   5. Insert Trocar A2 for the second assistant surgeon (5 mm): 4 cm above the symphysis pubis.
   6. Keep the camera port position fixed, and adjust the placement of other trocars according to the tumor location, patient body type, and surgeon's preference. Ensure that the operative center of the procedure remains at the tumor site. Maintain a distance of 8-10 cm between adjacent trocars to prevent mechanical arm collision or crossing.
      NOTE: We followed the China Anti-Cancer Association Guidelines for Robotic Surgery when arranging the trocar layout.
   7. Place the camera port at the upper right of the umbilicus.
6. Set the Bipolar mode to 45 W when using the bipolar coagulation forceps as the primary surgical instrument during the procedure.

2. Operation procedures and skills

1. Exploration and assessment of resectability
   1. Conduct a thorough exploration of the abdominal cavity, ensuring that no implants or metastatic nodules are found in the liver, gallbladder, small intestine, or pelvic cavity.
   2. Determine the tumor location intraoperatively, ensuring accurate identification within the sigmoid colon (Figure 3A). Use nanocarbon during preoperative colonoscopy to mark the site of the primary tumor that was previously removed endoscopically. Analyze the anatomy of the sigmoid colon, rectum, mesentery, and vessels to establish the distal and proximal resection margins. Evaluate the feasibility of transanal extraction of the specimen.
      NOTE: Normally, the surgeon will determine the tumor location, tumor size, as well as the depth of tumor invasion under laparoscopy.
2. Dissection and detachment
   1. Tilt the patient into a head-down position to move the small intestines away from the surgical site. Use small gauze to prevent the small intestine or mesentery from sliding and interfering with the surgical field.
   2. Grasp and lift the rectum and inferior mesenteric vessels ventrally, along with the mesentery, using two grasping forceps to clearly expose the surgical area.
   3. Use the bipolar coagulation forceps to open Toldt's space at the level of the sacral promontory. Push upward and downward along Toldt's space, then dissect downward to the right iliac vessel bifurcation.
      NOTE: Protect the hypogastric nerve, gonadal vessels, and ureter carefully during this process.
   4. Dissect the presacral space from proximal to distal. Increase the grasping force for the mesentery, and use sharp and blunt dissection to gradually expose and widen the space.
      NOTE: If the proper plane is entered posteriorly, no bleeding will occur, and the connective tissue in this plane can be divided easily.
   5. Gently draw the mesentery pedicle to the left ventral side using the grasping forceps, and expand the peritoneal window using the bipolar coagulation forceps. Expose the root of the inferior mesenteric artery (IMA) and separate it distally along its direction. Then, progressively isolate the three branches of the IMA-the left colic artery (LCA), the sigmoid artery (SA), and the superior rectal artery (SRA) (Figure 3B).
      NOTE: Care must be taken when exposing the root of the IMA because bleeding can occur readily with dissection. The surgeon can then sweep the tissue sufficiently around the vessels to perform clipping and transection.
   6. Dissect the lymph nodes at the root of the IMA. Expose and ligate SA, SRA, and the inferior mesenteric vein in turn. Place a gauze sponge on the posterior aspect of the mesosigmoid to protect the ureter and blood vessels.
3. Detachment and dissection of the sigmoid colon and the left side of the rectum
   1. Pull the mesentery of the sigmoid colon to the right to fully expose the junction between the mesentery of the sigmoid colon and the peritoneum. Coordinate the mechanical arm with the assistant's grasping forceps to achieve adequate tension.
   2. Dissect the lateral attachments of the sigmoid colon free. Completely mobilize the sigmoid colon using sharp and blunt dissection. Identify the gauze over the ureter through the mesosigmoid.
      NOTE: Great care should be taken to identify and avoid any injury to the gonadal vessels or the ureter.
4. Proximal division of the sigmoid colon and mesentery
   1. Incise the sigmoid mesocolon up to the bowel edge. Ligate the sigmoid vessels along the dissection. Clear the perisigmoid fat and epiploica along the length of the bowel for approximately 2-3 cm.
5. Distal rectal dissection
   1. Ensure that the distal resection margin is approximately 5 cm away from the tumor. Dissociate the mesentery along the same horizontal line, starting on the right side and then proceeding to the left side. Connect the left and right resection lines posteriorly.
      NOTE: Perform an additional clearance of approximately 2 cm of perirectal fat below the distal rectal transection line to facilitate the subsequent secondary closure.
6. Placement of the sterile plastic sleeve
   1. Choose a protective sleeve of the appropriate size based on the specimen's size and type to ensure it does not break during removal. Insert the sterile plastic sleeve through the trocar hole A1 and place it on one side of the abdominal cavity for later use.
7. Division of the sigmoid colon
   1. Transect the rectum at the lower bowel resection line using an endoscopic linear cutter (Figure 3C). Sterilize the ends of the intestine with povidone gauze.
8. Specimen extraction
   1. Position an assistant at the perineal side of the patient.
   2. Gently dilate the anus, then perform rectal irrigation using a povidone solution.
   3. Use the bipolar coagulation forceps to carefully expose the rectal stump and then disinfect it with iodophor gauze. Ask the assistant to hold an iodophor gauze against the rectum stump with an oval clamp to generate tension.
   4. Hold the oval clamp and carefully draw the transparent protective sleeve through the anus to create a sterile passage. Then, insert the anvil through the protective shield into the abdominal cavity.
   5. Make a longitudinal incision on the exposed area of the sigmoid colon above the tumor (Figure 3D). Introduce an iodophor gauze into the proximal sigmoid colon to disinfect the bowel lumen.
   6. Introduce the anvil into the bowel lumen of the proximal sigmoid colon (Figure 3E). Use the linear cutter to close the incision, leaving the anvil in the proximal sigmoid colon. Sterilize the stump of the sigmoid colon with povidone gauze (Figure 3F). Protrude the center rod of the anvil head from one side of the suture line on the sigmoid colon (Figure 3G).
   7. Place the specimen and used gauze into the sterile plastic sleeve before extracting them through the anus. Then, carefully tighten the protective sleeve to ensure that the contents are securely contained.
   8. Introduce an oval clamp into the pelvic cavity through the anus and tightly grasp one end of the specimen. Slowly extract it through the rectum and anus (Figure 3H). After extracting the specimen, check that the protective sleeve is intact to ensure it is not broken.
      NOTE: The purpose of removing the used gauze along with the specimen from the anus is to avoid "retrograde infection" caused by gauze fluid when the gauze is removed from the trocar hole, in line with the non-tumor and aseptic principles.
   9. Close the open rectal stump with a linear cutter. Place the stump into a specimen bag and extract it through trocar A1.
9. Digestive tract reconstruction
   1. Introduce the circular stapler from the gently dilated anus. Protrude the spike of the stapler from one side of the suture line.
   2. Click the center rod of the anvil into the distal part of the circular stapler. Check for twisting of the colon and mesentery. Ensure that the neighboring organs are away from the stapling line, then fire the stapler (Figure 3I). Twist open the stapler and withdraw it.
   3. Make a reinforced suture on the 'risk triangle' intra-abdominally to reduce the incidence of postoperative anastomotic fistula.
      ​NOTE: The 'risk triangle' refers to the intersection between the straight staple line (formed by linear cutter) and the circular staple line (formed by circle stapler) after anastomosis. The 'risk triangle' appears at one side or both sides of anastomosis, resulting from the overlap of staples, which easily leads to incomplete anastomosis and anastomotic leakage.
   4. Check the anastomosis for leaks by verifying the integrity of both the proximal and distal rings and performing an air test. Place two drainage tubes routinely in the anastomotic area on both sides of the pelvic cavity.

Results

The patient successfully underwent a Kangduo robot-assisted transanal specimen extraction radical sigmoidectomy without an auxiliary abdominal incision (NOSES-IV). The procedure lasted approximately 290 min, with an intraoperative blood loss of 50 mL. No operative complications and blood transfusions were required. The surgical specimen is shown in Figure 4. On the first postoperative day, the patient passed anal flatus, tolerated oral liquid intake, and walked independently. By the second p...

Discussion

Currently, surgical intervention is widely acknowledged as the primary therapeutic approach for managing colorectal cancer. The growing adoption of robotic systems in various surgical specialties, including colorectal, gastrointestinal, cardiothoracic, and gynecologic surgery, is driven by the increasing emphasis on minimally invasive techniques and continuous advancements in robotic platform technology. Compared to conventional laparoscopic surgery, surgical robot systems offer several advantages, such as high-definitio...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Bipolar coagulation forceps	Sagebot(Harbin,  China)	0701	Operation
Disposable Three-row-stapler Circular Stapler	Waston Medical(Changzhou,China)	IIIROWS-29-D	Laparoscopic Surgical Stapler
Fenestrated grasper	Sagebot(Harbin,  China)	301	Operation
Kangduo-SR-01 Surgical Robot	Sagebot(Harbin,  China)	KD-SR-01	Endoscopic surgical robot
Laparoscopic single use linear cutter	Ethicon (Somerville, NJ)	PSEE60A	Laparoscopic Surgical Stapler
Sterile protective cover	Sagebot(Harbin,  China)	M003-005;H001	Sterile barrier
STRATAFIX Spiral PGA-PCL	Ethicon (Somerville, NJ)	SXMD1B405	Reinforced suture
Trocars	Sagebot(Harbin,  China)	NA	Surgical ports