There are many points that need attention when using cell-free DNA (cfDNA) collection tubes, covering aspects such as before collection, during the collection process, and storage and transportation after collection. The following is a detailed introduction:

Patient Preparation: Fully explain the collection process to the patient to eliminate their nervousness and ensure the smooth progress of the collection. Generally, there is no need for the patient to have special dietary restrictions or other preparations. However, in some special cases, such as when conducting cfDNA testing related to tumors, blood collection should be avoided as much as possible in the short term after the patient has received treatments like radiotherapy and chemotherapy that may affect the test results, so as not to interfere with the accuracy of the test results.
Selection of Collection Tubes: Select the appropriate type and specification of cell-free DNA collection tubes according to the testing purpose and requirements. Collection tubes from different manufacturers may vary in aspects such as the type and content of anticoagulants, additives inside the tubes, etc., and their impacts on the stability of cfDNA and subsequent testing also differ.
Check the Expiry Date: Carefully check the expiry date and appearance of the collection tubes. Ensure that the collection tubes are not expired, and there are no damages, cracks, liquid leakage, or other situations on the tube body. The tube caps should be well-sealed to ensure the performance of the collection tubes and the reliability of the test results.

Blood Collection Technique: The blood collection personnel should be professionally trained and master the correct blood collection technique to minimize damage to blood cells and avoid hemolysis. Because hemolysis may lead to the release of DNA inside the cells into the plasma, interfering with the test results of cfDNA. Generally, venous puncture is used for blood collection. The application time of the tourniquet during blood collection should not be too long, usually not exceeding 1 minute, to avoid changes in blood components.
Blood Collection Volume: Strictly collect an appropriate amount of blood according to the requirements of the collection tube. Excessive blood collection may result in a relative shortage of anticoagulants, incomplete blood coagulation, and affect the extraction and testing of cfDNA. Insufficient blood collection may not meet the testing requirements, or the imbalance of the ratio between blood and anticoagulants may affect the stability of cfDNA.
Mixing Operation: After blood collection, immediately invert the collection tube gently 5-10 times to fully mix the blood with the anticoagulant and ensure the anticoagulation effect, preventing blood from clotting. However, pay attention to gentle movements and avoid violent shaking to prevent the rupture of blood cells and the breakage or degradation of cfDNA.

Storage Conditions: After collection, the collection tube should be processed and tested as soon as possible. If the test cannot be carried out immediately, it should be stored according to the instructions of the collection tube. Generally, the blood samples collected in cell-free DNA collection tubes are more suitable for storage at 4°C – 8°C, and the storage time should not be too long to prevent the degradation of cfDNA.
Transportation Requirements: If the collection tube needs to be transported to other laboratories or testing institutions, a professional transportation box should be used, and the temperature stability and vibration control during transportation should be ensured. At the same time, ensure that the collection tube will not be affected by external forces such as collision and extrusion during transportation to avoid tube body breakage or blood leakage.
Labeling and Recording: Clearly mark the patient’s name, gender, age, collection time, and other information on the collection tube, and make corresponding records to ensure the accuracy of the sample information, which is convenient for subsequent testing and result analysis.