Transfusion Venous<unk>  collected during<unk>  donation<unk>  for transfusion is obtained from human donors by<unk>  donation and stored in a<unk>  bank. There are many different<unk>  types in humans, the ABO<unk>  group system, and the Rhesus<unk>  group system being the most important. Transfusion of<unk>  of an incompatible<unk>  group may cause severe, often fatal, complications, so crossmatching is done to ensure that a compatible<unk>  product is transfused. Other<unk>  products administered intravenously are platelets,<unk>  plasma, cryoprecipitate, and specific coagulation factor concentrates. Intravenous administration Many forms of medication (from antibiotics to chemotherapy) are administered intravenously, as they are not readily or adequately absorbed by the digestive tract. After severe acute<unk>  loss, liquid preparations, generically known as plasma expanders, can be given intravenously, either solutions of salts (NaCl, KCl, CaCl2 etc.) at physiological concentrations, or colloidal solutions, such as dextrans, human serum albumin, or fresh frozen plasma. In these emergency situations, a plasma expander is a more effective life-saving procedure than a<unk>  transfusion, because the metabolism of transfused red<unk>  cells does not restart immediately after a transfusion. Letting In modern evidence-based medicine,<unk> letting is used in management of a few rare diseases, including hemochromatosis and polycythemia. However,<unk> letting and leeching were common unvalidated interventions used until the 19th century, as many diseases were incorrectly thought to be due to an excess of<unk> , according to Hippocratic medicine.
Blood
Serum 
Body fluid
Venous blood
Urine
Cord blood
Feces
Arterial blood