How does the clinical presentation of lower gastrointestinal (GI) bleeding vary with anatomic source and etiology?

Updated: Jul 26, 2019
  • Author: Burt Cagir, MD, FACS; Chief Editor: BS Anand, MD  more...
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The clinical presentation of LGIB varies with the anatomic source of the bleeding as well as with the etiology. Commonly, LGIB from the right side of the colon can manifest as maroon stools, whereas a left-sided bleeding source may be evidenced by bright red blood per rectum. In practice, however, patients with upper GI bleeding (UGIB) and those with right-sided colonic bleeding may also present with bright red blood per rectum if the bleeding is brisk and massive. Similarly, cecal bleeding may present with melena, which is typically seen with UGIB, suggesting no distinct method exists for determining the anatomic source of bleeding based solely on stool color.

The presentation of LGIB can also vary depending on the etiology. A young patient may present with fever, dehydration, abdominal cramps, and hematochezia caused by infectious or noninfectious (idiopathic) colitis. An older patient may present with painless bleeding and minimal symptoms caused by diverticular bleeding or angiodysplasia. LGIB can be mild and intermittent, as often is the case with angiodysplasia, or it may be moderate or severe, as may be the situation in diverticula-related bleeding.

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