Stephen J. Schueler, M.D.

Overview Incidence Risk Factors Symptoms Evaluation Treatment specialist Outlook Complications Underlying Cause Anatomy

Megacolon Anatomy

To better understand toxic megacolon, it helps to understand the anatomy of the intestines.

The intestine absorbs nutrients from food and liquids. The intestine is about 22 feet long in an adult. It includes the large intestine 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

Last Updated: Jan 6, 2011 References
Authors: Stephen J. Schueler, MD; John H. Beckett, MD; D. Scott Gettings, MD
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PubMed Megacolon References
  1. Gan SI, Beck PL. A new look at toxic megacolon: an update and review of incidence, etiology, pathogenesis, and management. Am J Gastroenterol. 2003 Nov;98(11):2363-71. [14638335]
  2. Imbriaco M, Balthazar EJ. Toxic megacolon: role of CT in evaluation and detection of complications. Clin Imaging. 2001 Sep-Oct;25(5):349-54. [11682295]
  3. Pascu M, Muller AR, Wiedenmann B, Dignass AU. Rescue therapy with tacrolimus in a patient with toxic megacolon. Int J Colorectal Dis. 2003 May;18(3):271-5. [12785330]
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