Many patients will have questions when drawing blood, how to draw blood vessels are flowery, red and purple. Vacuum blood collection tubes are indeed differentiated according to the different colors of the cap to facilitate the classification and processing of blood specimens. There are generally nine types, and four or five types may be used clinically. Now for you to describe: red cap is called ordinary serum tube, blood collection tube does not contain any additives, used for routine serum biochemistry, blood bank and serology-related tests; orange cap is fast serum tube, blood collection tube with procoagulant, to accelerate the coagulation process. The rapid coagulation tube can make the collected blood coagulate within five minutes and is suitable for the laboratory series of emergency serum; the golden head cap is an inert separating gel procoagulant tube, which is generally used for emergency serum biochemical tests. Because of the inert separating gel and procoagulant added in the blood vessel, the specimen can be centrifuged to completely separate some components of the blood and gather in the center of the tube to form a barrier, which can maintain a more stable state; the green cap is a heparin anticoagulation tube, which is generally used for red blood cell piezoelectricity test, red blood cell fragility test, blood gas analysis, blood sedimentation and general biochemical determination, but it is not suitable for doing blood coagulation test, because excessive heparin The light green head cap is also called plasma separator tube, and the lithium heparin anticoagulant is added inside the inert separator tube, which can achieve the purpose of rapid separation of plasma, and is also the best choice for electrolyte testing, so it is routinely used for plasma biochemical determination and emergency plasma biochemical testing such as ICU; the more common one is the purple head cap called EDTA anticoagulant tube, which is generally Used for general hematology test, but not for coagulation test and platelet function test, also can not be used for sodium, potassium, calcium, iron, alkaline phosphate determination; light blue head cap, is sodium citrate, coagulation test tube; black head cap is sodium citrate sedimentation test tube; finally gray head cap is potassium oxalate, sodium fluoride, sodium fluoride tube, suitable for blood glucose determination, generally not used for urease method to determine urea, also Not for the determination of alkaline phosphatase and starch, generally recommended for blood glucose testing.