Anatomy - Right Hemicolectomy, Robot-Assisted, with Complete Mesocolic Excision (CME) and UFA (Uncinatus First Approach) (Critical View Concept (CV))

The colon frames the loops of the small intestine along the inner abdominal wall and below the liver and stomach. Its position is intraperitoneal or secondary retroperitoneal. The primary function of the colon is to thicken the chyme by absorbing water. The total length of the colon averages 120–150 cm. It begins at the ileocecal valve and ends at the rectosigmoid junction, transitioning into the rectum.

The colon is divided into the following sections:

• Cecum (or Caecum) with the appendix
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon

The longitudinal muscle layers of the colon form three external, band-like structures known as taeniae, categorized as follows:

• Taenia mesocolica: Positioned toward the mesentery
• Taenia libera: Free on the surface, facing the abdominal wall
• Taenia omentalis: Connected to the greater omentum

Appendices epiploicae refer to fat appendages arising from the tela subserosa, located near the free taeniae.

Plicae semilunares are inward folds of all layers of the colonic wall, while haustra are the outward bulges between these folds.

Structures Relevant to Right Hemicolectomy

The following intestinal sections, in order from proximal to distal, are pertinent to a right hemicolectomy:

• Right colonic flexure and lateral right hemicolon
• Ascending colon
• Cecum with the appendix

• Definition: A blind-ending initial portion of the ascending colon, forming an outpouching; Latin: caecus = blind
• Length: 5 – 7 cm
• Synonyms: Caecum, blind gut
• Position: Intraperitoneal or secondary retroperitoneal, located below the ileocecal valve (valva Bauhini)
• Identification: Recognized by the taeniae and the vermiform appendix
• Vermiform appendix: Intraperitoneal, situated at the confluence of the taeniae on the cecal pole. Length: 6 – 20 cm, average: 8 cm. The three taeniae merge at the appendix base.

• Definition: The segment of the large intestine extending from the ileocecal valve (ileum entry) to the right colonic flexure (flexura coli dextra)
• Synonyms: Ascending colon or simply “ascending.”
• Position: Secondary retroperitoneal; extends from the lower right abdomen to the right flexure. It is fixed to the posterior abdominal wall via Toldt’s fascia.
• Length: 12 – 20 cm
• Identification: Identified by the longitudinal muscle bundles (taeniae), which retain their naming conventions from the transverse colon. The diameter is significantly larger than that of the descending colon.

• Synonyms: Transverse colon or simply “transverse.”
• Position: Intraperitoneal; mobile and fixed by its mesentery (mesocolon transversum). It traverses the abdominal cavity from the right to the left colonic flexure.
• Length: 30 –45 cm
• Identification: Characterized by the three taeniae and the greater omentum attached to the taenia omentalis. The left colonic flexure is positioned higher than the right, stabilized by the ligamentum phrenocolicum

Arterial Supply

The arterial blood supply to the right hemicolon is provided by branches of the superior mesenteric artery (A. mesenterica superior):

• Cecum: Supplied by the ileocolic artery (A. ileocolica)
• Ascending Colon:
  • Supplied by the A. ileocolica and the right colic artery (A. colica dextra)
• The A. colica dextra is inconstant, present in only about 60 % of cases. It typically originates from:
  • Superior mesenteric artery (70.8 %)
  • Middle colic artery (A. colica media) (15.4 %)
  • Ileocolic artery (A. ileocolica) (13.8 %)
• A “true” right colic artery is found during dissection after transection of the A. ileocolica in less than half of cases
• Transverse Colon: Supplied by the middle colic artery (A. colica media), which divides into a right and left branch after a short common trunk
• Left Colonic Flexure:
  • Represents a watershed zone between the territories of the superior and inferior mesenteric arteries
  • Anastomosis occurs between the superior mesenteric artery (A. colica media) and the inferior mesenteric artery (A. colica sinistra) near the left colonic flexure via the Riolan’s anastomosis. This anastomosis is either absent or insufficient in 20 % of cases

Venous Drainage

• Venous drainage occurs via the following veins into the superior mesenteric vein (V. mesenterica superior):
  • V. ileocolica
  • V. colica dextra
  • V. colica dextra superior
  • V. colica media
• These veins converge into the vena portae, which is formed at the confluence of the superior mesenteric vein, the splenic vein (V. lienalis), and other visceral veins posterior to the pancreatic head.

Henle’s Trunk (Truncus gastropancreaticus):

• A significant anatomical landmark located mid-cranially in the pancreatic head.
• It receives the following veins:
• V. gastroomentalis dextra
• Vv. pancreaticoduodenales
• V. colica dextra
• V. colica dextra superior
• In 10 % of cases, it also receives the V. colica media.
• It drains blood from the stomach, duodenum, pancreatic head, ascending colon, and parts of the transverse colon into the superior mesenteric vein.

Lymphatic Drainage

The key lymph nodes associated with the right hemicolon include:

• Nll. ileocolici
• Nll. colici dextri
• Nll. colici medii
• Nll. mesocolici

• Control via the Enteric Nervous System (Autonomic):
  • The right hemicolon receives autonomic innervation consisting of sympathetic and parasympathetic components
• Parasympathetic Innervation:
  • Supplied by branches of the vagus nerve (N. vagus), specifically via the posterior vagal trunk (Truncus vagalis posterior)
• Sympathetic Innervation:
  • Provided by the Nn. splanchnici major, minor, and lumbales and the ganglion mesentericum superius
• Cannon-Böhm Point:
  • Located near the left colonic flexure, this is the transition point where parasympathetic innervation shifts from the vagus nerve to the Nn. splanchnici pelvici

• This model facilitates understanding the surgical anatomy necessary for precise dissection during a right hemicolectomy with complete mesocolic excision (CME) using the Uncinatus First Approach (UFA)
• In this approach, anatomical structures of the same plane are visualized as pages of a book, which are systematically separated during surgery

Reference:

Strey CW, Wullstein C, Adamina M, et al. (2018). Laparoscopic right hemicolectomy with CME: standardization using the “critical view” concept. Surg Endosc 32(12):5021–5030.

Surgical Philosophy

The operative philosophy involves sequential dissection of each “page” of the “Open Book” model from the front and back before dividing vessels. The goal is to achieve maximum anatomical clarity and overview.

Key Anatomical “Pages” in the Open Book Model

1. Ileocolic Page:

• Includes the intestinal wall components of the ileocolic junction
• Relevant structures:
  • Meso: Contains the ileocolic artery and vein (A. ileocolica and V. ileocolica)
  • Superior mesenteric vein (V. mesenterica superior)
  • The small intestine segment, consisting of the ileum and jejunum

 2. Mesocolon-Transversum Page:

• Includes the transverse colon
• Relevant structures:
  • A. and V. colica media
  • Venous drainage of the right flexure (V. colica dextra sup. and V. colica dextra)

3. Mesogastric Page:

• Includes the stomach and mesogastrium
• Relevant structures:
  • A. and V. gastroepiploicae dextrae
  • Dorsal infrapyloric lymphatic drainage area

4. Retroperitoneal Page:

• Includes key retroperitoneal structures.
• Relevant structures:
  • Aorta
  • Inferior vena cava (V. cava)
  • Ureter
  • Gonadal vessels
  • Third part of the duodenum (Pars III duodeni or pars horizontalis)

Reference for Open Book Model and Critical View Concept

For detailed methodology, refer to the publication in Surgical Endoscopy:

 https://link.springer.com/article/10.1007/s00464-018-6267-0