Source:http://linkedlifedata.com/resource/umls/id/C0184104
UMD: Tubes designed to store blood samples drawn from a venipuncture through a blood-collection set. The tubes are usually connected using an adapter to a needle (that may include a Luer lock), which in turn punctures the stopper of the blood-collection set. These tubes frequently contain an appropriate substance to inhibit or enhance coagulation according to the intended use of the blood sample (e.g., heparin for chemical analysis, sodium citrate for plasma coagulation); the tube caps are usually color coded accordingly. Blood-collection tubes are made of glass or plastics; they are available either open or presealed after obtaining a relative vacuum in their interior.