Intestinal Segments and Urinary Diversion

Surgical Anatomy

Stomach

• Vascular organ
• Arterial blood supply
  • Primarily from 3 branches of the celiac trunk
    1. Left gastric artery
       • Supplies the lesser curvature
    2. Hepatic artery
       • Gives off the right gastric artery, which also supplies the lesser curve of the stomach, and the gastroduodenal artery, which supplies the antrum and duodenum before giving off the right gastroepiploic artery.
    3. The splenic artery
       • Gives off the vasa brevia (short gastrics), which supply the fundus and cardia, and the left gastroepiploic artery.
• When a wedge of fundus is used, it should not include a significant portion of the antrum and should never extend to the pylorus or all the way to the lesser curve of the stomach.
• INSERT FIGURE
• The right gastroepiploic artery meets with the left gastroepiploic artery; both supply collateral flow to the greater curve of the stomach. By use of the gastroepiploic vessels, a pedicle of stomach may be mobilized as far as the pelvis
• INSERT FIGURE

Small bowel

• ≈22 feet in length; however, may vary from 15-30 feet in length
• Differences between ileum and jejunum (5):
  • Ileum
    1. More distal
    2. Small diameter
    3. Multiple arterial arcades
    4. Smaller arcade vessels
    5. Thicker mesentery
  • Jejunum
    1. More proximal
    2. Larger diameter
    3. Single arterial arcades
    4. Larger arcade vessels
    5. Thinner mesentery
• The arcades receive their blood from the superior mesenteric artery
• Experimentally, up to 15 cm of small bowel can survive laterally to a straight vessel. In general, however, it should be assumed > 8 cm of small bowel will not survive away from a straight vessel
• In a post pelvic radiation patient, avoid use of 2 segments of the small bowel that may have been exposed to irradiation
  1. Last 2 inches of the terminal ileum
  2. 5 feet of small bowel beginning ≈6 feet from the ligament of Treitz (also known as the suspensory ligament of the duodenum), a thin muscle connecting the junction between the duodenum, jejunum, and duodenojejunal flexure to connective tissue surrounding the superior mesenteric artery and celiac artery
• INSERT FIGURE

Colon

• The large bowel is divided into the:
  1. Cecum
  2. Ascending colon
  3. Transverse colon
  4. Descending colon
  5. Sigmoid colon
  6. Rectum
• The ascending colon is fixed to the right posterior abdominal wall to the level of the hepatic flexure, at which point the hepatocolic ligament secures this portion of the colon to the liver.
• The transverse colon lies free within the abdominal cavity and is fixed in the left upper quadrant at the splenic flexure by the phrenocolic ligament. The transverse colon is attached to the stomach by the gastrocolic omentum.
  • Omentum flap should be based off of blood supply from the right gastroepiploic artery
    • The right and left gastroepiploic arteries supply the greater curvature and the omentum.
    • The pedicle can be based on either the right or left gastroepiploic artery; however, the caliber of the right gastroepiploic artery is usually larger, thus favoring its use.
• The descending colon is fixed to the left lateral abdominal wall
• The sigmoid colon may or may not lie free within the abdominal cavity
• Arterial blood supply
  • The colon receives its blood supply from the superior mesenteric artery, inferior mesenteric artery, and internal iliac arteries. The major arteries supplying the colon and rectum include the ileocolic, right colic, middle colic, left colic, sigmoid, superior hemorrhoidal, middle hemorrhoidal, and inferior hemorrhoidal arteries.
  • INSERT FIGURE
  • Weak points involving the vascular supply to the colon (3):
    1. Between the junction of the sigmoid and superior hemorrhoidal (Sudeck critical point) arteries
    2. Midpoints between the middle colic and right colic arteries
    3. Midpoint between the middle colic and left colic arteries (not shown in above diagram, but left colic artery is first branch of IMA (also not shown) and supplies the marginal artery§)
    • Although anastomoses in these areas usually heal well, provided the principles of proper technique are followed, it is recommended to select an area for the anastomosis to one side of these points
• Venous drainage
  • The inferior mesenteric vein drains into splenic vein.
  • The superior mesenteric vien combines with the splenic vein to form the hepatic portal vein
  • INSERT FIGURE