Blood Collection Tube Buying Guide
The blood collection tube is a one-time negative pressure vacuum glass tube that can realize quantitative blood collection, which needs to be used together with the venous blood collection needle.
The principle of vacuum blood collection tube
The blood collection tube with the head cover is drawn into different vacuum degrees in advance, and the negative pressure is used to automatically collect venous blood samples. One end of the blood collection needle is inserted into the human vein and the other end is inserted into the rubber stopper of the vacuum blood collection tube.
Human venous blood is drawn into the blood sample container through the blood collection needle under the action of negative pressure in the vacuum blood collection tube. Under one venipuncture, multiple tubes can be collected without leakage.
The volume of the lumen connected to the blood collection needle is small, and the impact on the blood collection volume can be ignored, but the probability of reverse flow is relatively small. If the volume of the lumen is large, part of the vacuum of the blood collection tube will be consumed, thereby reducing the collection volume.
Classification of vacuum blood collection tubes
A. Ordinary serum tube (red cap)
The blood collection tube contains no additives, no anticoagulant or procoagulant ingredients, only vacuum. It is used for routine serum biochemistry, blood bank and serology related tests, various biochemical and immunological tests, such as syphilis, hepatitis B quantification, etc. It does not need to be shaken after blood drawing. The type of specimen preparation is serum. After blood is drawn, it is placed in a 37°C water bath for more than 30 minutes, centrifuged, and the upper serum is used for later use.
B. Rapid serum tube (orange head cover)
There is a coagulant in the blood collection tube to speed up the coagulation process. The rapid serum tube can coagulate the collected blood within 5 minutes. It is suitable for emergency serum series tests. It is the most commonly used coagulation test tube for daily biochemistry, immunity, serum, hormones, etc. After blood is drawn, invert and mix 5-8 times. When the temperature is low, it can be placed in a 37°C water bath for 10-20min, and the upper serum can be centrifuged for later use.
C. Inert separation gel accelerator tube (golden head cover)
Inert separating gel and coagulant are added to the blood collection tube. Specimens are stable for 48 hours after centrifugation. Procoagulants can quickly activate the coagulation mechanism and accelerate the coagulation process. The type of specimen prepared is serum, which is suitable for emergency serum biochemical and pharmacokinetic tests. After collection, invert and mix 5-8 times, stand upright for 20-30 min, and centrifuge the supernatant for later use.
D. Sodium citrate ESR test tube (black cap)
The sodium citrate concentration required for the ESR test is 3.2% (equivalent to 0.109 mol/L), and the ratio of anticoagulant to blood is 1:4. Contain 0.4mL of 3.8% sodium citrate, and draw blood to 2.0mL. This is a special test tube for erythrocyte sedimentation rate. The sample type is plasma, which is suitable for ESR. Immediately after blood drawing, invert and mix 5-8 times. Shake well before use. The difference between it and the test tube for coagulation factor testing is that the concentration of anticoagulant is different from the blood ratio, which should not be confused.
E. Sodium citrate coagulation test tube (light blue cap)
Sodium citrate mainly acts as an anticoagulant by chelating calcium ions in blood samples. The anticoagulant concentration recommended by the National Committee for Standardization of Clinical Laboratories is 3.2% or 3.8% (equivalent to 0.109mol/L or 0.129mol/L), and the ratio of anticoagulant to blood is 1:9. The vacuum blood collection tube contains about 0.2 mL of 3.2% sodium citrate anticoagulant, and the blood is collected to 2.0 mL. The type of specimen preparation is whole blood or plasma. Immediately after collection, invert and mix 5-8 times. After centrifugation, take the upper plasma for use. Suitable for coagulation experiments, PT, APTT, coagulation factor examination.
F. Heparin anticoagulation tube (green cap)
Heparin was added to the blood collection tube. Heparin directly has the effect of antithrombin, which can prolong the coagulation time of the specimen. For emergency and most biochemical experiments, such as liver function, kidney function, blood lipids, blood sugar, etc. It is suitable for red blood cell fragility test, blood gas analysis, hematocrit test, erythrocyte sedimentation rate and general biochemical determination, but not suitable for blood coagulation test. Excessive heparin can cause aggregation of white blood cells and cannot be used for white blood cell counts. It is also not suitable for leukocyte classification because it can make the blood film stained with a light blue background. It can be used for blood rheology. The sample type is plasma. Immediately after blood collection, invert and mix for 5-8 times, and take the upper plasma for use.
G. Plasma separation tube (light green head cover)
Adding heparin lithium anticoagulant to the inert separation rubber tube can achieve the purpose of rapid separation of plasma, which is the best choice for electrolyte testing. For emergency and most biochemical experiments, such as liver function, kidney function, blood lipids, blood sugar, etc. Plasma samples can be loaded directly on the machine and are stable for 48 hours under refrigeration. It can be used for blood rheology. The sample type is plasma. Immediately after blood collection, invert and mix for 5-8 times, and take the upper plasma for use.
H, potassium oxalate/sodium fluoride (gray head cover)
Sodium fluoride is a weak anticoagulant, which is usually used in combination with potassium oxalate or sodium ethiodate, and its ratio is 1 part of sodium fluoride and 3 parts of potassium oxalate. 4mg of this mixture can make 1ml of blood not coagulate within 23 days and inhibit the decomposition of sugar. It cannot be used for the determination of urea by urease method, nor for the determination of alkaline phosphatase and amylase. It is recommended for blood sugar testing. It contains sodium fluoride or potassium oxalate or disodium ethylenediaminetetraacetate (EDTA-Na) spray, which can inhibit the enolase activity in glucose metabolism. After drawing blood, invert and mix 5-8 times. The liquid plasma is reserved for use, and it is a special tube for rapid blood glucose measurement.
I. EDTA anticoagulation tube (purple head cover)
Ethylenediaminetetraacetic acid (EDTA, molecular weight 292) and its salts are an amino polycarboxylic acid, suitable for general hematology tests, and are the preferred test tubes for blood routine, glycosylated hemoglobin, and blood group tests. Not suitable for coagulation test and platelet function test, nor for the determination of calcium ion, potassium ion, sodium ion, iron ion, alkaline phosphatase, creatine kinase and leucine aminopeptidase, suitable for PCR test. Spray 100ml of 2.7% EDTA-K2 solution on the inner wall of the vacuum tube, blow dry at 45°C, collect blood to 2ml, invert and mix 5-8 times immediately after blood draw, and mix well for use. The sample type is whole blood, which needs to be mixed evenly before use.
Precautions for vacuum blood collection tubes
A. Selection and injection sequence of vacuum blood collection tubes
Select the corresponding test tube according to the items to be tested. The blood injection sequence is culture flask, ordinary test tube, test tube containing solid anticoagulant, and test tube containing liquid anticoagulant.
The purpose of following this sequence is to minimize analytical errors due to specimen collection.
Blood distribution order:
①The order of using glass test tubes: blood culture test tube, serum tube without anticoagulant, sodium citrate anticoagulation test tube, other anticoagulant test tube.
②The order of using plastic test tubes: blood culture test tube (yellow), sodium citrate anticoagulation test tube (blue), serum tube with or without blood coagulation activator or gel separation, gel with or without gel Heparin tube (green), EDTA anticoagulation tube (purple), and blood glucose breakdown inhibitor tube (grey).
B. Blood collection site and posture
Infants and young children can take blood from the medial and lateral borders of the thumb or heel according to the method recommended by the World Health Organization, preferably the head and jugular vein or the anterior fontanelle vein.
For adults, choose the median cubital vein, the back of the hand, the wrist joint, etc. without congestion and edema, and the vein in individual patients is on the back of the elbow joint.
Patients in outpatient clinics take more sitting positions, and patients in wards take more recumbent positions. When taking blood, instruct the patient to relax and keep the environment warm to prevent venous contracture. The restraint time should not be too long, and it is forbidden to beat the arm, otherwise it may cause local blood concentration or activate the coagulation system. Try to choose a thick and easy-to-fix blood vessel for puncture to ensure that the needle hits the blood. The angle of needle insertion is generally 20-30°. After seeing the blood return, move forward slightly in parallel, and then put on the vacuum tube. The blood pressure of individual patients is low. After the puncture, there is no return blood, but after the negative pressure tube is put on, the blood flows out.
C. Strictly check the validity period of blood collection tubes
It must be used within the validity period, and must not be used when there is foreign matter or sediment in the blood collection tube.
D. Paste the barcode correctly
Print the barcode as directed by the doctor, and paste it on the front after checking, and the barcode cannot cover the scale of the blood collection tube.
E. Timely inspection
Blood samples are required to be sent for inspection within 2 hours after collection to minimize the influencing factors. When submitting for inspection, avoid strong light exposure, shelter from wind and rain, anti-freeze, anti-high temperature, anti-shake, and anti-hemolysis.
F. Storage temperature
The storage environment temperature of blood collection tubes is 4-25°C. If the storage temperature is 0°C or lower than 0°C, it may cause the rupture of blood collection tubes.
G, protective latex cover
The latex sleeve at the end of the puncture needle can prevent the blood collection test tube from continuing to bleed and pollute the surrounding area, and plays the role of sealing the blood collection to prevent environmental pollution. The latex sleeve must not be removed. When collecting blood samples from multiple tubes, the rubber of the blood collection needle may be damaged.
