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* Descending colon,
* Descending colon,
* Sigmoid colon
* Sigmoid colon
* Rectum
* Rectumhu
|style="padding: 5px 5px; background: #F5F5F5;" align="left" |
|style="padding: 5px 5px; background: #F5F5F5;" align="left" |
* Inferior mesenteric artery (IMA)
* Inferior mesenteric artery (IMA)
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| colspan="4" style="padding: 5px 5px; background: #F5F5F5;" align="center" |ɸ -Except lower rectum, which drains into the systemic circulation.
| colspan="4" style="padding: 5px 5px; background: #F5F5F5;" align="center" |ɸ -Except lower rectum, which drains into the systemic circulation.
|}
|}
[[Image:Colonic blood supply1.gif|thumb|center|300px|Source:]]

Revision as of 17:36, 20 November 2017

Lower GI bleeding is defined as any bleed that occurs distal to the ligament of Treitz.

Incidence

  • In the United States the incidence of LGIB ranges from 20.5 to 27 per 100,000 persons per year.

Age

  • There is a greater than 200 fold increase from the third to the ninth decade of life.

Classification

  • Lower GI bleeding can be classified into 3 groups based on the severity of bleeding:
    • Occult lower GI bleeding
    • Moderate lower GI bleeding
    • Severe lower GI bleeding

Blood supply

  • The SMA and IMA are connected by the marginal artery of Drummond.
  • This vascular arcade runs in the mesentery close to the bowel.
  • As patients age, there is increased incidence of occlusion of the IMA.
  • The left colon stays perfused, primarily because of the marginal artery.
Lower GI Tract Arterial Supply Venous Drainage
Midgut
  • Distal duodenum jejunum
  • Ileum
  • Appendix
  • Cecum
  • Ascending colon
  • Hepatic flexure
  • Proximal transverse colon.
  • Superior mesenteric artery (SMA)
  • Portal system.
Hindgut
  • Distal one-third of the transverse colon
  • Splenic flexure
  • Descending colon,
  • Sigmoid colon
  • Rectumhu
  • Inferior mesenteric artery (IMA)
  • Portal system ɸ
ɸ -Except lower rectum, which drains into the systemic circulation.
Source: