Differential Diagnoses for Blood in Stool

Common Causes of Hematochezia

The American Gastroenterological Association notes that diverticulosis is the most common cause of hematochezia in adults, accounting for 30-41% of cases, typically presenting as painless, large-volume bright red blood 1, 3
Angiodysplasia is the second most common cause, particularly in patients over 65 years, often associated with chronic kidney disease and aortic stenosis, accounting for 20-40% of cases 1, 3
The American College of Gastroenterology recommends considering inflammatory bowel disease, such as ulcerative colitis and Crohn's disease, as a cause of hematochezia, especially in patients with diffuse mucosal ulceration or focal vessel erosion 4, 5
Ischemic colitis accounts for 6-21% of hematochezia cases, typically in elderly patients with vascular disease 1, 3
Colorectal cancer or polyps represent 11-22% of cases, with risk increasing with age and family history 1, 2, 3

Hemorrhoids are a very common cause of hematochezia, accounting for 14-24% of cases, typically presenting with bright red blood coating stool or on toilet paper, and may have associated prolapse or thrombosis 6, 7, 8
Anal fissures present with postdefecatory pain and minor bleeding, best visualized with anal eversion 6, 8
Anorectal varices are distinct from hemorrhoids, cross the dentate line into the rectum, and are associated with portal hypertension 9, 2, 8

Up to 15% of patients with severe hematochezia have an upper GI bleeding source, including peptic ulcer disease, gastritis, or esophageal varices, particularly important in patients with hemodynamic instability, hemoglobin drop, or transfusion requirements 2, 3

Patients over 65 years are more likely to have diverticulosis and angiodysplasia as the cause of hematochezia 1
Younger patients under 50 years are more likely to have hemorrhoids, anal fissures, and inflammatory bowel disease, though colorectal cancer risk cannot be excluded based on age alone 2

Radiation proctitis occurs 9 months to 4 years after pelvic radiation 1
Solitary rectal ulcer syndrome can present with massive bleeding 9, 2
Post-polypectomy bleeding is an iatrogenic cause in patients with recent colonoscopy 3
Aortoenteric fistula is a rare but catastrophic cause, consider in patients with prior aortic graft surgery 3

The American College of Gastroenterology recommends never assuming hemorrhoids are the cause without proper evaluation, as symptoms attributed to hemorrhoids frequently represent other pathology, including colorectal cancer 6, 8
Portal hypertension causes anorectal varices, not hemorrhoids, requiring different management, with varices being compressible, serpiginous submucosal veins that cross the dentate line 8, 9, 2