This problem is not particularly common but painless blood loss from the gut which can lead to anaemia can occur due to various problems in childhood. One of course is a condition known as polyps which are benign outgrowths of tissue in the gut. This is not cancer and bowel cancer is very, very rare in childhood. A diagnosis of polyps can be made at endoscopy and colonoscopy and these can be removed during this procedure. Other causes of bleeding might be a specific problem called a Meckel’s Diverticulum which is a small pocket in the small bowel of stomach lining producing acid which can ulcerate. This is a remnant of the embryological development of the foetus and needs a special type of scan for this to be diagnosed. Vascular abnormalities in the gut are quite rare but do cause blood loss from the gut from time to time. Colitis which is inflammation of the colon usually causes other symptoms such as abdominal pain and diarrhoea as well as blood loss.