Health Questions and Answers

Question: Does melena indicate a right-sided colonic source and hematochezia a left-sided source?

Answer:

Usually. The color of stool depends on colonic transit time. If the stool remains in contact with bacteria that degrade hemoglobin, the resulting stool is melanic. Although right-sided lesions are usually associated with melena (dark, tarry stools) and left-sided lesions with hematochezia (the passage of bright red blood per rectum), the opposite can also be seen. Therefore, the evaluation of a patient with hematochezia must include examination of the proximal colon.

Reference: Sleisenger MH, Fordtran JS (eds): Gastrointestinal Disease: Pathophysiology, Diagnosis, and Management, 7th ed. Philadelphia, W.B. Saunders, 2003.

One Response to “Question: Does melena indicate a right-sided colonic source and hematochezia a left-sided source?”

  1. set piatti Says:

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