Haemorrhoids, often known as piles, are enlarged veins around the anal region and these can seriously endanger a patient's health for a number of different reasons. Haemorrhoids can be a source of infectionInvasion by organisms that may be harmful, for example bacteria or parasites. and sometimes the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. in the enlarged vein may form a clotBlood that has coagulated, that is, has moved from a liquid to a solid state. resulting in a thrombosed haemorrhoidSwollen blood vessel in the lining of the anus, also known as piles. which is extremely painful. Although severe bleeding from haemorrhoidsSwollen blood vessels around the anus, also known as piles. is unusual, anaemiaA reduced level of haemoglobin, which carries oxygen in the blood. Anaemia causes tiredness, breathlessness and abnormally pale skin. may result if the bleeding is prolonged.