When and if you ever get off the toilet, take a look, and see blood you may well panic. Particularly the first time, and very particularly if the amount seems large! Bloody Stool is traditionally viewed as a sign of cancer and seriousness!
If this happens to you, or someone you know, you will be interested in the information in this article. The first thing you should know about bloody stool is that there are three forms of that blood and that whichever form you see tells you quite a bit, immediately, about the situation.
When a patient says he sees blood in the stool he is rarely wrong. The only thing that he can confuse with fresh blood (Hematochezia) is a red dietary pigment that might escape digestion. The pigment in beets, if eaten in large quantities, can produce a dark red stool; this is more common in children than in adults. I suppose that other red dietary pigments could cause confusion too. If you are in doubt you can ask if the blood diffuses into the water of the toilet bowl.
Fresh blood diffuses rather rapidly and turns the water a familiar light yellowish pink-red color, while beet pigment goes into solution without a change in color. Many people know that black stools (melena) can mean blood in the stool, so when a patient says he sees blood you should ask if he means black blood, red blood, or something in between ("dark blood").
Blood turns black in the gut lumen because reduced hemoglobin is dark and because bacteria alter the porphyrin pigments. Most of this conversion occurs in the right colon where the colonic bacteria are most active.
Thus if blood in the stool looks entirely fresh, its source is the distal one-third of the colon; if it is completely black, its source is likely to be above the cecum; if it is mixed black and red, the source is somewhere in between. This rule holds for low to moderate rates of bleeding. Large-volume bleeding above the cecum creates a loose watery stool
because of the osmotic effect of the blood constituents.
The flushing of the colon does not give the bacteria time to convert the hemoglobin completely from red to black. Still,
the blood rarely looks entirely fresh even in large-volume bleeding from above the cecum.
Black stools can also result from the ingestion of iron, bismuth (usually in Pepto-Bismol). Also, from the excessive intake of spinach and other greens that is cooked and eaten in large quantities by vegetarians and enthusiasts for "ethnic" diets. You must ask about such medicines and foods when you see a patient who complains of black stools.
The most usual explanation would be Hemorrhoids. I am limiting this article, for the moment, to bright red blood in the stool. USUALLY this comes from a tear in the tissue of the rectum, or from hemorrhoids (also sometimes spelled hemorrhoids), and would normally be combined with constipation, straining to have a bowel movement, and the consequent bleeding from the rectal tissue or hemorrhoids.
TO BE CONTINUED NEXT WEEK
