From the Guidelines
Blood in stool, or hematochezia, is most commonly caused by hemorrhoids, diverticulosis, angiodysplasia, and colorectal cancer, as evidenced by a review of lower gastrointestinal bleeding cases 1. The most frequent causes of lower gastrointestinal bleeding include:
- Hemorrhoids, which are swollen veins in the rectum or anus that can bleed during bowel movements
- Diverticulosis, where small pouches form in the colon wall and may bleed
- Angiodysplasia, which are vascular lesions in the colon that can cause bleeding
- Colorectal cancer, which can cause intermittent bleeding, often without pain Other causes of blood in stool include:
- Inflammatory bowel diseases like Crohn's disease or ulcerative colitis, which can cause bloody diarrhea due to inflammation and ulceration of the intestinal lining
- Infections such as bacterial dysentery, E. coli, or parasitic infections, which can lead to bloody diarrhea
- Upper gastrointestinal bleeding from conditions like peptic ulcers or gastritis, which can result in darker, tarry stools (melena) when blood is digested as it moves through the intestines
- Certain medications like aspirin, NSAIDs, and blood thinners, which can increase the risk of gastrointestinal bleeding It is essential to evaluate any instance of blood in stool by a healthcare provider, especially if it's persistent, accompanied by pain, weight loss, or changes in bowel habits, as it could indicate a serious condition requiring prompt treatment 1.
From the Research
Common Reasons for Blood in Stool
Some of the most common reasons for blood in stool include:
- Ulcerative colitis (UC), a chronic idiopathic inflammatory bowel disorder of the colon that causes continuous mucosal inflammation extending from the rectum to the more proximal colon, with variable extents 2
- Crohn's disease (CD), another type of inflammatory bowel disease that can cause bleeding in the stool 3
- Diverticulitis, a condition where small, bulging pouches (diverticula) in the digestive tract become inflamed or infected, which can cause bleeding 4
- Colorectal cancer, which can develop in patients with chronic ulcerative colitis or Crohn's disease 5
- Inflammatory bowel disease (IBD), which includes both UC and CD, and can cause bleeding in the stool due to increased protease activity and extracellular matrix turnover 6
Disease Characteristics
The characteristics of these diseases can vary, but some common features include:
- Bloody diarrhea with or without mucus, rectal urgency, tenesmus, and variable degrees of abdominal pain that is often relieved by defecation in UC 2
- Similar symptoms to UC, but with a more unpredictable course and potential for complications such as bowel obstruction or fistulas in CD 3
- Increased risk of colorectal cancer in patients with chronic UC or CD 5
- Different profiles of extracellular matrix turnover, which can reflect disease activity in CD 6