What is the most common cause of lower GI bleeding in adults?

The most common cause of lower gastrointestinal (GI) bleeding in adults is diverticulosis. Diverticulosis involves the formation of small pouches (diverticula) in the colon wall, which can become inflamed or bleed. The prevalence of diverticulosis increases with age, and this condition is particularly common in older adults due to factors like diet and changes in bowel habits.

When diverticula become eroded or inflamed, they can lead to significant bleeding, often presenting as bright red blood in the stool. This makes diverticulosis a leading cause of lower GI bleeding in adults, as it is frequently encountered in clinical practice and is well-documented in medical literature.

Hemorrhoids are a common source of rectal bleeding and occur in many individuals but are not as prevalent a cause of lower GI bleeding as diverticulosis in the adult population overall, especially compared to the age-related predisposition towards diverticular disease. Colitis and malignancy are also important causes of lower GI bleeding but typically occur with different frequency rates.