Stephen J. Schueler, M.D.

Overview Symptoms Underlying Cause Anatomy

Gastrointestinal Bleeding Lower Anatomy

To better understand lower gastrointestinal bleeding, it helps to understand the anatomy of the lower gastrointestinal tract.

The intestine is a long, continuous, tube inside the body. It lets the body absorb nutrients from food and liquids. The intestine is about 22 feet long. It includes the large intestine (colon) and the small intestine.

The small intestine has three parts:

  • Duodenum:
    • Connects to the stomach
  • Jejunum:
    • Middle portion of the small intestine
  • Ileum:
    • Lower portion of the small intestine that connects to the cecum (first part of the large intestine)

The large intestine is also known as the colon. It is the last portion of the intestine.

The colon has several parts, including:
  • Cecum:
    • The portion of the colon that connects to the ileum (small intestine). The appendix is a finger-like pouch that comes off of the cecum.
  • Ascending colon:
    • The first section after the small intestine, located on the right side
  • Transverse colon:
    • Sits horizontally across the upper abdomen
  • Descending colon:
    • Located on the left side of the abdomen
  • Sigmoid:
    • A short, S-shaped section above the rectum
  • Rectum:
    • The lowest internal part of the colon

Intestinal anatomy:
  • Entire gastrointestinal tract
  • Intestines and other abdominal organs
  • Blood vessels of the intestines
  • The appendix is a small pouch that protrudes from the wall of the large intestine. It is located at the point where the small intestine turns into the large intestine.

Last Updated: Dec 17, 2010 References
Authors: Stephen J. Schueler, MD; John H. Beckett, MD; D. Scott Gettings, MD
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PubMed Gastrointestinal Bleeding Lower References
  1. Farrell JJ, Friedman LS. Review article: the management of lower gastrointestinal bleeding. Aliment Pharmacol Ther. 2005 Jun 1;21(11):1281-98. [15932359]
  2. Hernandez-Diaz S, Rodriguez LA. Incidence of serious upper gastrointestinal bleeding/perforation in the general population: review of epidemiologic studies. J Clin Epidemiol. 2002 Feb;55(2):157-63. [11809354]
  3. Khuroo MS, Khuroo MS, Farahat KL, Kagevi IE. Treatment with proton pump inhibitors in acute non-variceal upper gastrointestinal bleeding: a meta-analysis. J Gastroenterol Hepatol. 2005 Jan;20(1):11-25. [15610441]
  4. Lewis B, Goldfarb N. Review article: The advent of capsule endoscopy--a not-so-futuristic approach to obscure gastrointestinal bleeding. Aliment Pharmacol Ther. 2003 May 1;17(9):1085-96. [12752345]
  5. Olds GD, Cooper GS, Chak A, Sivak MV Jr, Chitale AA, Wong RC. The yield of bleeding scans in acute lower gastrointestinal hemorrhage. J Clin Gastroenterol. 2005 Apr;39(4):273-7. [15758618]
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