Melena
It is another type of intestinal bleeding, but it is often confounded with other signs. Melena is a dark-colored stool that’s also foul-smelling, and it is caused by blood that’s been spilled into the intestinal lumen and decomposed by the gut microbiota, which gives out the characteristic odor. Melena is a sign that the alteration is located farther from the anal opening, which gives enough time to the intestinal microbiota to decompose the blood. Many different gastrointestinal alterations would likely cause melena, and only a clinician with diagnostic tests would be able to rule out cancer as a possibility.