Hemorrhoids: This is the most common cause of painless rectal bleeding (PR bleeding), especially in adults. Hemorrhoids are swollen veins in the rectum or anus that can bleed during bowel movements.

Anal Fissure: A tear in the lining of the anus can cause painful rectal bleeding, especially during and after bowel movements.
Diverticulosis: A condition where small, bulging pouches (diverticula) develop in the digestive tract, which can cause bleeding.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause rectal bleeding, diarrhea, and abdominal pain.
Gastrointestinal Infections: Infections like gastroenteritis can cause rectal bleeding, especially in children.

Colorectal Cancer: Although less common, colorectal cancer can cause rectal bleeding, and it is crucial to rule out this diagnosis, especially in older adults or those with a family history.
Angiodysplasia: A condition where there is a malfunction of the blood vessels in the gut, which can cause bleeding.
Meckel's Diverticulum: A congenital anomaly of the small intestine that can cause rectal bleeding, especially in children.

Intussusception: A condition where a part of the intestine slides into another part, which can cause rectal bleeding, especially in children.
Arteriovenous Malformation (AVM): A rare condition where there is an abnormal connection between arteries and veins, which can cause rectal bleeding.
Solitary Rectal Ulcer Syndrome: A condition where there is a single ulcer in the rectum, which can cause rectal bleeding and pain.