Surgical procedure
The patient assumes a lithotomy position, while the operator stands on the left side, the assistant on the right side, and the scope holder between the legs(Fig. 1A,B). The pneumoperitoneum pressure is maintained at 12-15mmHg. A standard exploration of the abdominal cavity is conducted, with particular attention paid to the peritoneum, omentum, and visceral surface for the presence of metastatic lesions. Upon detection of the primary lesion, the tumor's location and size were identified, and the operative range was established. Following exploration of the abdominal cavity, the greater omentum was positioned above the transverse colon and below the liver, while the small intestine was placed in the left upper abdomen, thereby exposing the root of the ileum mesentery. The assistant successfully grasped the appendix and the ileum mesentery 15 cm away from the ileocecal region without any harm. Our surgical procedure is comprised of seven distinct modules.
1.Tail-side approach
The surgeon utilized a triangular traction technique by grasping the distal ileum mesentery root at a distance of 1 cm from the caudal aspect. To gain access to the loose layer between Toldts' fascia and the retroperitoneal subfascia (Gerota's fascia), the peritoneum is incised 1 cm cephalad to the right iliac artery using an ultrasound knife. The two fascia's exhibit a slight difference in color, and the vascularity direction within Toldts' fascia is predominantly perpendicular to the long axis of the body, while the direction of capillary vascularity within the retroperitoneal subfascia is mostly parallel to the long axis of the body, which can aid in identifying the correct layer. To prevent harm to the genital vessels and ureter, it is recommended to maintain the seamless integrity of the retroperitoneal subfascia while continuing to widen the gap cephalad. The assistant should utilize grasping forceps on both the left and right sides to lift the ascending colonic mesentery, thereby exposing the junction of the descending and horizontal duodenum medially. Further expansion of the anterior pancreaticoduodenal space along the anterior duodenum is advised. The medial termination point of the separation lies adjacent to the projection of the inferior mesenteric vein, while the lateral boundary extends towards the lateral border of the right kidney and the superior limit is positioned at the junction of the duodenal bulb and descending portion. To demarcate the entire cleared area, gauze strips are positioned anteriorly to both the pancreas and duodenum, serving as the right-hand border(Fig. 2A).
2.Superior mesenteric vein dorsal free
The assistant proceeds to lift the left and right mesentery of the superior mesenteric vein, turning caudally medially. This action results in the unfolding of the dorsal aspect of the superior mesenteric vein and the release of the peritoneum dorsal to the superior mesenteric vein. The area of focus is distal to the confluence of the ileocolic veins and proximal to the level of the gastrocolic trunk (Henle trunk). Subsequently, the assistant prepares the right side of the superior mesenteric vein for clearance by placing gauze in position(Fig. 2B).
3. Localization of the mesenteric root of the transverse colon
The small intestine is situated in the inferior abdominal region. During the surgical procedure, the assistant elevates both the left and middle portions of the transverse mesocolon, while the primary scalpel secures the right side of the ligamentous flexure mesentery. The triangular transverse mesocolon is then extended and unfurled, and the ultrasonic scalpel is employed to incise the mesentery from the base of the left side of the middle colonic artery depression, releasing it in a cephalad direction along the superior border of the pancreas and converging with the posterior wall of the stomach. A gauze strip is filled in as the left border of the entire clearing area(Fig. 2C).
4.Lateral cephalic approach
The caudal traction of the greater omentum and transverse colon is accompanied by the assistant's upward traction of the lateral arterial arches of the greater curvature of the stomach, specifically the right and left sides, while the surgeon simultaneously pulls the omentum caudally to establish a triangular retraction. Starting from the center of the triangle, the greater omentum is incised to access the omental sac. Subsequently, the greater omentum is dissected towards the left and extended towards the right by freeing it along the gastrocolic mesenteric gap. This dissection exposes the gastric mesentery on the cranial side and the colonic mesentery on the caudal side, extending towards the right until the anterior wall of the duodenum and the head of the pancreas are visible. Finally, the posterior gap of the ascending colon is connected to reveal the positioning gauze for the caudal approach. The dissection of the deep gastrocolic mesentery exposes the branches of the Henle trunk, including the right gastroretinal vein on the cephalic side, the superior anterior pancreaticoduodenal vein, and the paramedian right colic vein on the caudal side. The paramedian right colic vein is subjected to free ligation at the root. The main trunk of the superior mesenteric vein is exposed by freeing along the inferior margin of the pancreas towards the deep side. The peritoneal layer covering the root of the transverse colonic mesentery is incised on the left side of the root of the middle colonic artery, thereby exposing the gauze located at the root of the transverse colon. The gauze is then extracted and spread out over the superior mesenteric vein's main trunk, extending towards the gastrocolic mesenteric space, which demarcates the cephalolateral boundary of the entire sweeping region. This procedure concludes the comprehensive demarcation of the gauze strip's wrapping area(Fig. 2D).
5. Central mesenteric region clearance(Fig. 2E)
The small intestine is situated in the lower left quadrant of the abdomen. The assistant grasps the mesenteric opening located at the base of the transverse colonic mesentery and elevates the vascular projection of the ileocolon, thereby facilitating the unfolding of the right hemicolectomy. The ileocecal mesentery is incised at the inferior margin of the depression beneath the ileocolon and extends into the posterior interval of the ascending colon. Upon exposing the primary trunk of the superior mesenteric vein, the grasping forceps should be adjusted to a distance of 3 cm from the root of the ileocolic vessels. Subsequently, a pulling force in the direction of 11 points should be applied, while collaborating with an assistant to rectify the central mesenteric region. This maneuver will result in the complete liberation of the dorsal aspect of the superior mesenteric vein and the entire region will be secured (with priority given to the superior mesenteric vein). This marks the point at which the dorsal aspect of the superior mesenteric vein is released. The dissection of the superior mesenteric vein involves a cephalad approach along the left side of the main trunk, with blunt separation occurring 5 mm anterior to the vein and subsequent cutting of the vein surface using an ultrasound knife. This dissection method is deemed relatively safe for anterior dissection of the superior mesenteric vein due to the absence of apparent adhesions to surrounding tissues and the majority of its branches being located on either side of the main trunk. The cephalad removal and dissection of the ileocolic vein and artery at their root, along with the clearance of the 203rd group of lymph nodes, is performed. In cases where the ileocolic artery is situated dorsal to the superior mesenteric vein, dissection of the artery is carried out at the left margin of the superior mesenteric vein. In instances where the right colonic artery or vein is absent, the former is removed at the left margin of the superior mesenteric vein if it is located dorsal to it. Following this, group 213 lymph nodes are cleared. The Henle trunk is then freed cephalad, and the paramedian right colonic vein is dissected and connected to the cephalad free plane. The procedure involves the continued dissection of the middle colonic vein in a cephalad direction towards the superior mesenteric vein and to the left of the Henle trunk. The vein is then ligated at its root to facilitate disconnection and enlargement for connection with the cephalad free plane. Additionally, the middle colonic artery is dissected in a cephalad direction and ligated at its root to enable disconnection. In cases of ascending colon tumours, the bifurcation of the middle colonic artery is further dissected, with the right branch being disconnected while preserving the left branch. Finally, the 223 groups of lymph nodes are cleared. The lymph nodes located in group 223 have been effectively cleared. Subsequently, the cephalic free plane is utilized to completely clear the area, and the gauze is subsequently extracted.
6. Lateral free(Fig. 2F)
The assistant executes a lateral maneuver to extract the transverse colon 10 cm from the colonic hepatic flexure towards the 4 o'clock position, simultaneously drawing the ascending colon 10 cm from the colonic hepatic flexure towards the 6 o'clock position. The hepatic colonic ligament is then carefully opened in proximity to the liver to release the colonic hepatic flexure in an undamaged state. The assistant manipulates the colonic hepatic flexure towards the 3 o'clock position while simultaneously manipulating the appendix towards the 5 o'clock position, thereby separating and spreading the lateral peritoneum of the ascending colon and achieving complete liberation of the right hemicolon. In order to prevent torsion during specimen retrieval, the right hemicocele and omentum are repositioned.
7. Anastomosis(Fig. 3)
An incision was created in the upper abdomen, measuring approximately 5 cm in length, to access the right hemicolectomy and greater omentum. The resection of the ileum, including the tumor and right hemicolectomy, was performed, followed by an anastomosis of the lateral ileo-transverse colon outside the body. The pneumoperitoneum was reconstructed, and the mesenteric fissure was sutured. A drainage tube was placed in the right upper abdomen, and the intestinal tube was inserted before closing the abdomen.