Allergic Proctocolitis: This condition is a common cause of rectal bleeding in infants, often associated with the introduction of new foods or allergens, leading to an allergic reaction in the rectum. The presence of bloody mucous stool is characteristic, especially in breastfed infants or those with a family history of allergies.

Anal Fissure: A tear in the anal mucosa can cause painful defecation and bleeding, presenting as spotty blood in the stool. This is common in infants due to hard stools or constipation.
Gastroenteritis: Viral or bacterial infections can lead to inflammation of the gastrointestinal tract, resulting in bloody stools, especially if the infection involves the colon.
Cow's Milk Protein Allergy: An immune reaction to cow's milk proteins can cause inflammation in the gut, leading to symptoms including bloody stools, especially in formula-fed infants.

Intussusception: A condition where a part of the intestine slides into another, which can cause bowel obstruction and ischemia. It's a medical emergency that can present with bloody stools, abdominal pain, and a palpable mass.
Hirschsprung's Disease: A congenital condition characterized by the absence of ganglion cells in the colon, leading to severe constipation and potentially enterocolitis, which can cause bloody stools.
Infectious Colitis: Certain bacterial infections (e.g., Salmonella, Shigella) can cause severe colitis, presenting with bloody diarrhea, which requires prompt antibiotic treatment.

Meckel's Diverticulum: A congenital anomaly of the small intestine that can cause bleeding due to the presence of ectopic gastric mucosa. It's a rare cause of gastrointestinal bleeding in infants.
Juvenile Polyps: Benign growths in the colon can cause rectal bleeding, though they are less common in infants and more typically found in older children.
Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis are rare in infants but can present with chronic diarrhea, blood in the stool, and failure to thrive.