Crohn’s Disease is a form of Inflammatory Bowel Disease (IBD) that causes chronic inflammation anywhere along the digestive tract, from the mouth to the anus. This persistent inflammation leads to various bowel symptoms, including visible or hidden blood in the stool. The presence of blood typically indicates active disease or a complication in the gastrointestinal tract, and its occurrence is directly related to the underlying damage caused by the disease.
Why Crohn’s Disease Causes Bleeding
The mechanism behind bleeding in Crohn’s Disease is rooted in the chronic inflammation it causes. Unlike other forms of IBD that may affect only the innermost lining, Crohn’s inflammation is often transmural, extending through the entire thickness of the intestinal wall. This deep inflammation leads to the formation of sores and deep erosions known as ulcers.
These ulcers are open wounds within the digestive tract. As they deepen, they penetrate the small blood vessels that supply the lining of the bowel. When this erosion occurs, blood leaks directly into the intestinal lumen, eventually mixing with the stool.
Another common feature is the development of deep fissures, which are long, narrow ulcers. These fissures, particularly in the anal area, are prone to irritation during a bowel movement and can be a direct source of noticeable blood. Fistulas, which are abnormal tunnels connecting parts of the intestine, can also cause bleeding if they involve the erosion of a blood vessel.
The location of the inflammation is a major factor; Crohn’s affecting the colon or rectum is far more likely to cause blood in the stool than disease isolated to the small intestine. Bleeding is generally a sign of active disease, indicating that the inflammatory process is currently damaging the intestinal tissue. Chronic, low-level bleeding over time can lead to iron deficiency anemia, even if the blood is not visibly present.
Understanding the Appearance of Blood
The visual appearance of blood in the stool offers clues about the location of the bleeding within the gastrointestinal tract. Blood originating from the lower parts of the bowel, such as the colon or rectum, typically appears as bright red blood. This is because the blood has not been exposed to digestive enzymes for a long period. Bright red blood may be seen mixed in the stool, on the surface of the stool, or on the toilet paper after wiping.
Bleeding that occurs higher up in the digestive tract, such as in the small intestine, undergoes digestion and chemical changes before it is passed. This results in a dark, tarry, and sticky stool, medically known as melena. The dark color is due to the oxidation of hemoglobin in the blood. Melena suggests a bleed higher up, though Crohn’s is less commonly associated with this presentation than with lower gastrointestinal bleeding.
It is also possible for bleeding to be occult, meaning hidden and not visible to the naked eye. This slow, chronic loss of blood may only be detectable through specific laboratory tests on a stool sample. Even if no blood is seen, persistent occult bleeding can still cause symptoms of anemia, such as fatigue or paleness.
Related Symptoms of Crohn’s Disease
Blood in the stool is usually accompanied by several other gastrointestinal and systemic symptoms that characterize a Crohn’s flare-up. The most common symptom is persistent diarrhea, which can be frequent and urgent, resulting from the inability of the inflamed intestine to properly absorb water. This often leads to abdominal cramping and pain, which can be constant or come in waves, often localized to the lower right abdomen.
Systemic symptoms occur because the inflammation affects the entire body. Fatigue is a common symptom, frequently linked to chronic inflammation, poor nutrient absorption, and anemia from blood loss. Unintentional weight loss is also common, resulting from reduced appetite and the malabsorption of nutrients by the damaged intestine.
A person experiencing active Crohn’s Disease may also have a low-grade fever, reflecting the body’s ongoing inflammatory response. Other complications can include mouth sores, joint pain, or skin issues, which are known as extra-intestinal manifestations of the disease. The combination of persistent diarrhea, abdominal discomfort, and blood in the stool warrants immediate medical consultation to evaluate the activity of the disease and prevent potential complications.