Blood collection tubes must be drawn in a specific order to avoid cross-contamination of additives between tubes. The recommended order of draw for plastic vacutainer blood collection tubes are:

First – blood culture bottle or tube (yellow or yellow-black top)

Second – coagulation tube (Blue top).

Third – non-additive tube (red top)

Last draw – additive tubes in this order:

SST (red-gray or gold top). Contains a gel separator and clot activator.

Sodium heparin (Green top)

PSGT (light green top). Contains lithium heparin anticoagulant and a gel separator.

EDTA (lavender top)
Glucose , Oxalate/fluoride (Grey top) or other additives
NOTE: Tubes with additives must be thoroughly mixed. Clotting or erroneous test results may be obtained when the blood is not thoroughly mixed with the additive.
You may ask why we need follow this sequences. Please at the same time see blood collection tubes and tests chart.

1. Blood cultures should always be drawn first to reduce the potential hazard bacterial, fungal, quantitative, CMV and/or other specimen contamination. Blood culture vials and tubes:

Blue, Purple culture vials contain enriched Soybean-Casin broth with CO2 and are used for bacterial and fungal blood cultures.

Yellow stopper tubes contain nutrient solution and Black stopper Isolator tubes contain a blood lysis solution.

2. Light Blue tubes must be drawn prior to collection of serum tubes to prevent contamination with clot activator and interference with the coagulation cascade.

Light Blue stopper tubes contain sodium citrate most often used for coagulation studies.

1ml of blood into a light blue 3.2% citrate discard tube must be collected prior to drawing light blue top tube(s) for the following special coagulation studies: Platelet Function Screen and Whole Blood Platelet Aggregation of Platelet Mapping. A discard tube is not required for any other Special Coagulation testing.

3.Serum tubes are coated on the inside walls with clot activator because the surface of a plastic tube does not promote coagulation.

a. Red stopper tubes are used mainly for serology and chemistry tests. They may also be used for testing in Blood Bank.

b. SANLI SST (serum separator tubes) have a red stopper with a yellow ring on top and are used for a wide variety of testing. These tubes contain a gel which separates the cells from the serum when the tube is centrifuged.

Tubes with additives:

Green stopper tubes contain lithium heparin and are used for most tests that require plasma. Green stopper tubes are also used for NH3 which requires immediate transport.

Green stopper tubes containing sodium heparin are used for special testing such as Cytogenetics.

Lavender stopper tubes contain EDTA and used for hematology studies.

Above order of blood collection draw also can apply to capillary blood collection tubes.Capillary tubes for blood collection we normally have non-additive, EDTA, serum separator, Heparin and Glucose.

Finally, blood collection tube guide can summarized as 3 points:

A. Sterility should be consider first, blood culture and blood collection should be the first.

B. Additives can not pollute non-additives, so red (no additives tubes) without need in front of other tubes that containing additives.

C. Additives should also be distinguished also. Additives have a great influence on other tests. The order of additives is that they can’t affect the latter experiments. Coagulation function testing requires higher requirements, so blue tubes rank first.

Compared with a traditional tissue biopsy, one of the advantages of liquid biopsy is that it can reflect the comprehensive information of the lesions. The precise treatment is based on gene analysis of tissue samples from tumors and other lesions. The traditional methods are a surgical biopsy and puncture biopsy. Because of the strong heterogeneity of tumor cells, traditional methods can only obtain samples. The genetic information of location can not reflect the comprehensive information of tumors as a whole. The second advantage is that it can be monitored at high frequency. Gene changes in cancer cells may lead to drug resistance. High-frequency monitoring is necessary to achieve accurate drug use. Liquid biopsy can be achieved by simple intravenous blood sampling, which can meet the needs of high-frequency monitoring. The third advantage is that it can significantly reduce the cost and risk of patients. The cost of lung biopsy is several times higher than that of liquid biopsy, and there is a greater risk of complications.

II. It is because of the irreplaceable technical advantages of liquid biopsy that it has brought broad market prospects.

China has many policies and events in supporting for liquid biopsy technology: The Ministry of Science and Technology proposed to invest 60 billion RMB in precise medical treatment before 2030; The Health Planning Commission “Notice of the Medical Administration of the National Health and Family Planning Commission on the Pilot Work of Clinical Application of High Throughput Gene Sequencing Technology for Tumor Diagnosis and Treatment Project”; Ministry of Health “Notice on Preliminary Research on Indoor Quality Assessment of Tumor Diagnosis and Treatment by High-throughput Sequencing Testing (Multi-gene Detection)”; Medical Planning Commission “Technical Guidelines for Gene Detection of Drug Metabolic Enzymes and Drug Targets (Trial Implementation)” and “Technical Guidelines for Individualized Tumor Therapy Monitoring (Trial Implementation)”; Development and Reform Commission “About the First Batch of Bases” Reply to the Construction Plan of the Demonstration Center for Detection Technology Application. At present, the clinical access of liquid biopsy products in China can be achieved in two ways (similar to FDA+CLIA dual channel in the United States). One is through CFDA approval for listing; the other is as a self-built laboratory project (LDTs) used in medical laboratories approved by the Health and Planning Commission, which is not restricted by CFDA registration of instruments and reagents. It is more rapid and widely used by many gene testing companies.

III. How is the development of a liquid biopsy?

The following branches of liquid biopsy have been developed according to the different detectors:

1.CTC technology: Circulating Tumor Cell (CTC) is a tumor cell that is free from the blood circulation system. It is derived from the primary tumor tissue and is an important way of tumor cell metastasis. It is an important factor for recurrence and mechanism of cancer death. As a tumor cell, CTC not only contains the DNA information of the tumor but also contains information such as genome and proteome, which is a rich source for studying tumor tissue information.

2.cfDNA/ctDNA technology: Cell-free DNA (cfDNA) is a DNA fragment derived from cells that is free from the blood circulatory system. It is mainly derived from DNA fragmentation, DNA fragments of necrotic cells, and cell secretion. The most important class of cfDNA is Circulating Tumor DNA (ctDNA), a DNA fragment from the tumor genome that enters the blood circulatory system, carrying mutations, insertions, deletions, rearrangements, copy number abnormalities and/Or methylation and other genetic information.

3.Exosomes: Exosome is a vesicle secreted by cells. The vesicles contain proteins, DNA, messenger RNA, and some non-coding RNAs. They are the carriers of communication between cells, and the occurrence and development of tumors. There is a correlation between metastasis and drug resistance. Tumor cells use these vesicles as carriers to help them escape the surveillance of the immune system. These vesicles guide the direction of tumor cell migration and create a microenvironment suitable for tumor growth.

4. Circulating RNA technology: Circulating RNA is extracellular RNA present in the blood or other body fluids, mainly mRNA, miRNA and other types of RNA, which are closely related to cellular metabolism under physiological and pathological conditions. Clinical research focuses on prenatal diagnosis and early diagnosis of tumors.

IV. What are the advantages and disadvantages of various types of liquid biopsy?

In practice, because of the large number of CTC patients in the advanced stage of cancer and the small number of patients in the early stage, the current major clinical application is limited to predicting the prognosis by detecting the number of CTCs in postoperative or advanced patients. The most mature application of cfDNA is NIPT (non-invasive prenatal genetic testing). The analysis of fetal free blood by analyzing the venous blood of pregnant women to determine the probability of fetal suffering from Down syndrome has become a common screening method for prenatal and postnatal education in China. The most common application of ctDNA is to drive gene detection, such as peripheral blood EGFR mutation detection, to provide a basis for medication guidance. Exosomes and circulating RNA are still in the early stage of research, and there are few practical applications.

In general, CTC technology and cfDNA technology research are more abundant, practical applications are more, and the understanding of its advantages and defects is more mature and comprehensive. Among them, CTC technology started earlier and clinical research is more abundant, but the development of this technology is limited by the characteristics of high technical difficulty, low detection rate, and strong heterogeneity. Especially the separation of CTC is very difficult, and it can not meet the needs of clinical examination. Compared with CTC, ctDNA capture is relatively easy, and detection methods are more mature. Although ctDNA enrichment still has bottlenecks, it can meet some detection needs of patients with advanced cancer, give valuable diagnostic opinions, and ctDNA is The detection of gene mutations is uniquely advantageous, and thus more and more applied to the treatment guidance and monitoring of cancer. In recent years, the focus of corporate and capital on liquid biopsy has shifted from CTC to ctDNA, which has become the most commonly used in the market. Liquid biopsy technology. In addition, with the large-scale investment of some companies such as SANLI MEDICAL in the field of ctDNA technology, the number of clinical research and trials will increase rapidly, and the problem of early screening of cancer may also be solved. In addition, ctDNA has also been found to have potential applications in another popular technology for tumor immunotherapy, which can be used to guide immunotherapy or predict the efficacy of immunotherapy.