The following are the precautions for the use of cell-free DNA blood collection tubes:

Before Sample Collection

• Select appropriate blood collection tubes: According to the testing requirements and the requirements of the testing platform, choose the appropriate type of cell-free DNA blood collection tubes. For example, there are multiple products available for different storage durations and different anticoagulants. It is necessary to ensure that the selected blood collection tube matches the subsequent testing process.
• Check the quality of blood collection tubes: Before use, carefully examine the appearance of the blood collection tubes to ensure that there are no damages, cracks, or discolorations on the tubes, that the labels are clear and complete, and that the amount of anticoagulant or protective agent and other liquids inside the tubes is sufficient and there are no abnormal phenomena such as precipitation or turbidity.
• Prepare the patient: Inform the patient of the precautions before blood collection, such as diet and work and rest schedules. Generally, it is recommended that the patient maintain a normal diet and regular work and rest before blood collection, avoid strenuous exercise, drinking alcohol, staying up late, etc. Fasting or preparing according to specific testing requirements may be necessary before blood collection.

During Sample Collection

• Strictly follow aseptic operation: The blood collection personnel should wear sterile gloves, masks, etc., use sterile blood collection needles and blood collection instruments, and conduct strict disinfection treatment on the blood collection site to prevent exogenous DNA from contaminating the sample and affecting the accuracy of the test results.
• Accurate collection volume: Collect an appropriate amount of blood sample according to the label requirements of the blood collection tube to avoid collecting too much or too little blood. Excessive blood collection may lead to a relative insufficiency of the anticoagulant or protective agent in the blood collection tube, causing blood coagulation or cell lysis and the release of a large amount of genomic DNA, which will interfere with the detection of cell-free DNA (cfDNA). Insufficient blood collection may not meet the testing requirements.
• Skilled blood collection technique: During the blood collection process, ensure that the blood collection needle accurately punctures the vein and avoid repeated punctures to prevent hemolysis. Hemolysis will cause the DNA inside the cells to be released into the plasma and contaminate the cfDNA sample, affecting the test results.

After Sample Collection

• Timely processing and storage: After the blood sample is collected, gently invert the blood collection tube as soon as possible to make the blood fully mix with the anticoagulant or protective agent in the tube to prevent blood coagulation. Then store the sample according to the requirements of the blood collection tube. Generally, it is necessary to store it under specific temperature conditions, such as low-temperature refrigeration or freezing, and record the storage time and conditions.
• Transportation conditions: If the sample needs to be transported to other laboratories for testing, ensure the stability of the temperature and the safety of the sample during transportation. Use specialized transportation containers, such as incubators and ice packs, to keep the sample within the appropriate temperature range and avoid severe vibration and collision.
• Avoid repeated freezing and thawing: If the sample needs to be stored for a long time or used multiple times, try to avoid repeated freezing and thawing as much as possible. Repeated freezing and thawing may cause cell lysis and the release of more genomic DNA, affecting the quality of cfDNA and the test results. It is recommended to divide and store the sample when it is frozen for the first time so that it can be retrieved as needed later.