My 2 year old has rectal bleeding what causes this and how can i prevent it?

BLEEDING PER RECTUM:: Some causes: chronic constipation with hard stool with blood; drinking red colored juice/drink/fruit can mimic blood, rectal or distal colon polyp; bacillary dysentery, associated with abdominal pain, fever in a sick child. Rectal bleeding as a part of systemic diseases, e.g. Henoch schonlein purpura, hemorrhagic diseases, etc. Whatever is the cause, s/he needs to be seen immediately.