Blood Collection Tubes – Definition, Significance of Color Coding

Blood collection is an essential part of medical diagnosis, and it is crucial to use the right type of blood collection tube (BCT) to ensure accurate results. In this article, we will discuss the different types of BCTs used in in-vitro analysis, their composition, and the significance of proper mixing of blood with the additives present in the tubes.

There are two main types of BCTs used in clinical laboratories for in-vitro analysis of blood samples – serum and plasma. Blood is collected in air-tight, color-coded BCTs with rubber stoppers at the top, also known as vacutainer or evacuated tubes. These tubes are either made of plastic or glass and are used in various diagnostic fields like chemical/biochemical, hematological, molecular, and serological testing.

The color of the BCTs determines the type of additives added in the tubes. It is crucial to thoroughly mix the tubes with the additives to ensure accurate results. All tubes containing anticoagulants should be mixed gently 10-12 times to mix the additive with the blood and prevent clotting. Inadequate mixing of blood with the additives may result in errors in the test results.

In many cases, more than one test can be performed using a single BCT. However, it is important to check with the laboratory for the minimum amount of blood required for each test.

In conclusion, the proper selection and use of BCTs play a critical role in the accuracy of in-vitro analysis results. It is crucial to understand the type of BCTs used, the significance of proper mixing of blood with the additives, and the importance of checking with the laboratory for the minimum amount of blood required for each test. By following these guidelines, healthcare professionals can ensure that they receive accurate results and make informed decisions in patient care.

Components of Blood Collection Tube

Blood collection tubes are an essential component in medical procedures for collecting and preserving blood samples for laboratory analysis. With a shape and size similar to that of test tubes, these tubes are equipped with stoppers and are made from either plastic or glass materials. In this article, we will delve into the components and characteristics of blood collection tubes, including the tube wall, rubber stopper, stopper lubricant, and tube surfactant.

• Tube Wall: The tube wall is the outer shell of the blood collection tube, and it is an important factor in determining the durability and risk of cross-contamination. Measuring 50-150mm in length and 10-20mm in diameter, the tube wall is made from either borosilicate or soda-lime glass, or polyethylene terephthalate, polyethylene, or polypropylene plastic. The plastic tubes are more durable and carry a lower risk of cross contamination compared to glass tubes.
• Rubber Stopper: The rubber stopper is a colorful and easily penetrable seal that is used to close the blood collection tube after the blood sample has been collected. Made from butyl rubber or halogenated butyl rubber, the stopper is designed to self-seal after the needle has been removed, preventing any contamination of the blood sample.
• Stopper Lubricant: Lubricants, such as silicone oils, glycerol, and fluids, are applied to the stopper to make it easier to remove and insert. These lubricants help reduce friction, making it easier to handle the blood collection tube and preventing any damage to the rubber stopper.
• Tube Surfactant: The choice of tube surfactant is critical as it can interfere with antibodies and disrupt the reactions required for laboratory analysis. The surfactant is used to reduce non-specific adsorption, improve blood flow, and prevent the absorption of proteins, red blood cells, and platelets to the tube wall.

Blood collection tubes play an important role in medical procedures for collecting and preserving blood samples for laboratory analysis. Understanding the components and characteristics of these tubes, including the tube wall, rubber stopper, stopper lubricant, and tube surfactant, can help ensure the accuracy of laboratory results and prevent any contamination of the blood sample. Whether you are a healthcare professional or a patient, it is important to be informed about the features of blood collection tubes to make informed decisions about your medical care.

Additional components of Blood Collection Tube

In addition to the general components, the following additional components are included in different colour caps:

• Separating gel: These are contained in SST (serum separating tubes) and are used to separate serum from clots or entire blood. The utilised gel is a thixotropic gel that is sandwiched between the packed cells and the serum.
• Anticoagulants: In blood collection tubes, potassium EDTA, trisodium citrate, potassium oxalate, sodium fluoride, and heparin salts act as anticoagulants and chelating agents.
• Clot activator particles: Clot activator particles are contained in plastic tubes, and the particles either intrinsically or extrinsically activate clot. Ellagic acid, thrombin, snake venoms, and thromboplastin are extrinsic activators of blood coagulation. Glass, bentonite, kaolin, and diatomaceous earth intrinsically activate clot.
• Protease inhibitors: EDTA and citrate are likewise protease inhibitors since they hinder the activation of proteases. Other protease inhibitors used in vacutainer tubes are aprotinin and sulfonyl halides.

Order of Draw in Blood Collection Tube

Blood collection is a crucial procedure in the medical field, and it’s essential to ensure that the samples collected are free from contamination. One of the ways to achieve this is by following the principle of “order of draw,” which outlines the recommended sequence for transferring blood from collection tubes. In this article, we will dive into the details of this principle and understand why following the correct order is crucial.

The order of draw is a standardized procedure that outlines the sequence in which different tubes should be filled with blood. The main purpose of this order is to avoid cross-contamination between additives, which could affect test results.

Step by Step Guide to the Order of Draw

Step 1: Blood Culture Bottle or Yellow/Yellow-Back – Top Tube The first tube that should be filled is the blood culture bottle or the yellow/yellow-back top tube. This tube is used for microbiological testing and is, therefore, essential to be collected first to avoid any contamination from other tubes.

Step 2: Coagulation Tube (Light Blue Color) – The second tube to be filled is the coagulation tube, which is light blue in color. This tube is used for tests that measure blood clotting time. However, as this tube may get contaminated by tissue, fluids, or thromboplastins, it’s advisable to draw in a non-additive tube first, followed by the light blue top.

Step 3: Non-Additive Tube (Red Top) – The third draw should be on a non-additive tube, which is usually red in color. This tube is used for tests that require a sample without any preservatives.

Step 4: Additive Tubes in the Following Order:

• SST (Red-Gray or Gold Top)
• PST (Light Green Top)
• Sodium Heparin (Dark Green Top)
• EDTA (Lavender Top)
• ACDA or ACDB (Pale Yellow Top)
• Oxalate/Fluoride (Light Gray Top)

It’s crucial to follow the order of draw for additive tubes to avoid cross-contamination and ensure accurate test results. The SST tube contains a gel separator and clot activator, while the PST tube has a lithium heparin anticoagulant and a gel separator. Sodium heparin is the dark green top, EDTA is the lavender top, ACDA or ACDB is the pale yellow top and has acid citrate dextrose, and Oxalate/fluoride is the light gray top.

It’s essential to remember not to transfer a sample from one collection tube to another or mix blood from different collection tubes. Doing so could result in inaccurate test results and compromise the overall validity of the procedure.

In conclusion, the order of draw in blood collection is a crucial principle that ensures the accuracy of test results and prevents cross-contamination between additives. By following the recommended sequence, healthcare professionals can ensure that the collected samples are of the highest quality and provide the most accurate results.

Color of the Cap and Its Purpose

As discussed previously, the colour of the tube’s cap indicates its function and anticoagulant content. The colour of the tubes also impacts the required clotting time and the number of inversions required once blood is deposited into the tubes. Standard laboratory procedures call for the utilisation of yellow, pink, blue, lavender/purple, red, green, and light blue colour tubes.

The colour of the anticoagulant tube and its application are as follows:

1. Marble or Gold (SST) (Plastic tubes with clot activator and gel for serum separation)

What are Clot Activator Plastic Tubes?

Clot activator plastic tubes are a type of blood collection device designed to enhance the accuracy and reliability of blood tests. They are made of high-quality plastic material that is safe for human use and comes with a built-in clot activator and gel that facilitates the separation of serum from the blood cells. The clot activator helps the blood to form clots quickly, reducing the risk of contamination and ensuring the accuracy of the test results.

How Do Clot Activator Plastic Tubes Work?

The working principle of clot activator plastic tubes is straightforward. The blood is collected in the tube, which contains the clot activator and gel. After the collection, the tube is inverted five times to mix the clot activator with the blood. This process triggers the clotting process, and the gel helps to separate the serum from the blood cells. The serum can then be tested for various markers, and the results are compared against the normal range to diagnose any underlying medical conditions.

Clotting Time Required

One of the key benefits of using clot activator plastic tubes is the reduced clotting time. It takes only 30 minutes for the blood to form clots in the tube, compared to the traditional methods that can take up to several hours. The quick clotting time helps to minimize the risk of contamination and preserve the integrity of the blood sample, leading to more accurate test results.

Commonly Associated Tests

Clot activator plastic tubes are commonly used in a wide range of tests, including chemistry profiles, electrolytes, lipid panel, hepatic panel, hepatitis panel, thyroid studies, iron studies, cancer markers, lithium, alcohol, vitamin B12, vitamin D, hormone studies, cardiac markers, lidocaine, folate, therapeutic drugs (except carbamazepine), tricyclic antidepressants, salicylate, and homocysteine (ON ICE). These tests help diagnose various medical conditions, monitor the effectiveness of treatments, and assess the overall health of an individual.

In conclusion, the use of clot activator plastic tubes in blood tests has revolutionized the medical industry, providing faster and more accurate results. The tubes are easy to use, and their quick clotting time minimizes the risk of contamination, preserving the integrity of the blood sample. The wide range of tests that can be performed with these tubes makes them a versatile solution for medical diagnoses and treatments. If you’re looking for a reliable and accurate blood collection method, consider using clot activator plastic tubes.

2. Plain Red (Silicone coated made of glass)

Advantages of Silicone Coated Glass

One of the primary benefits of silicone coated glass is that it eliminates the need for tube inversions. This not only saves time but also reduces the risk of sample contamination and the chance of errors in results. In addition, the silicone coating provides a smooth and uniform surface that prevents sample buildup and makes cleaning easy.

Reduced Clotting Time

Another major advantage of silicone coated glass is that it reduces the clotting time required for tests. In traditional glass tubes, clotting time can range anywhere from 30 minutes to two hours, depending on the type of sample being tested. With silicone coated glass, however, the clotting time is reduced to just 60 minutes, making it one of the fastest and most efficient testing methods available.

A Wide Range of Tests

Silicone coated glass can be used for a wide range of tests, including the Rheumatoid factor (RF) test, RPR (rapid plasma reagin test), uric acid, PTH (parathyroid hormone), insulin, prealbumin, magnesium, BhCG (beta-human chorionic gonadotropin) test, FT3/FT4 (free triiodothyronine and free thyroxine), digoxin, amylase, lipase, cortisol, CRP (C-reactive protein) test, and C-peptide. This versatility makes silicone coated glass an essential tool in any medical testing laboratory.

In conclusion, silicone coated glass has revolutionized the world of medical testing by providing faster and more accurate results. Its ability to eliminate tube inversions, reduce clotting time, and be used for a wide range of tests makes it a must-have tool for any laboratory. If you’re looking to improve the efficiency and accuracy of your testing processes, look no further than silicone coated glass.

3. Green (Lithium heparin (light green tube tubes containing lithium heparin and gel for plasma separation) is the additive.)

The Role of Lithium Heparin as an Anticoagulant

Lithium heparin is a commonly used anticoagulant in the medical field, especially in the collection of blood samples for diagnostic tests. It is added to blood samples to prevent coagulation and preserve the integrity of the blood cells. Lithium heparin is stored in light green tubes and is mixed with the blood sample by performing eight tube inversions.

No Clotting Time Required

One of the advantages of using lithium heparin as an anticoagulant is that it does not require a clotting time. This means that the blood sample can be processed immediately after collection, reducing the chances of inaccurate results due to the formation of clots.

General Chemistry Requests and Associated Tests

Green and light green vacutainer tubes containing lithium heparin are preferable for all STAT general chemistry requests. These tests include chemistry profiles, ionized calcium, lipid panel, hepatic panel, cardiac markers, rheumatoid factor (RF) test, ammonia (ON ICE), and therapeutic drugs (except for VANC and lithium). The light green tube is also used for the BhCG Quant test.

In conclusion, the use of lithium heparin as an anticoagulant and the proper mixing of the anticoagulant with the blood sample through tube inversions are critical in ensuring accurate diagnostic test results. By choosing the right anticoagulant and following proper collection techniques, healthcare providers can maximize the accuracy of their diagnostic tests and provide patients with the best possible care.

4. Gray (Sodium Fluoride/Potassium Oxalate)

The Importance of Additives in Blood Sampling

Additives play a vital role in blood sample testing, as they help to preserve the integrity of the sample and prevent degradation. Sodium fluoride and potassium oxalate are commonly used additives, as they effectively inhibit glycolysis and prevent the breakdown of glucose. This ensures that accurate glucose levels can be obtained, even when drawing blood samples from a long distance from the hospital.

Eight Tube Inversions: The Key to Proper Mixing

In order to ensure proper mixing of additives with blood, 8 tube inversions are recommended. This simple step helps to distribute the additives evenly throughout the sample, providing consistent results. It’s important to note that this process should be performed carefully, as over-agitation can cause hemolysis, leading to inaccurate results.

No Clotting

Time Required An added advantage of using sodium fluoride and potassium oxalate as additives is that they do not require a clotting time. This eliminates the need for waiting for the blood to clot, allowing for quicker results. This is particularly important in emergency situations, where prompt diagnosis and treatment are vital.

Choosing the Right Tube for Specific Tests

When it comes to blood sample testing, it’s essential to choose the right tube for the specific test being performed. Gray top tubes are often used when checking glucose levels, as they preserve glucose and are particularly useful for samples drawn a long distance from the hospital. On the other hand, lactic acid testing is best performed using ON ICE tubes, which helps to preserve the integrity of the sample.

In conclusion, the proper use of additives, 8 tube inversions, and appropriate tube selection are all crucial elements of obtaining accurate blood sample results. By understanding the significance of these factors, healthcare providers can ensure the best possible outcomes for their patients. The combination of sodium fluoride and potassium oxalate as additives, 8 tube inversions, and the right tube selection can provide consistent and accurate results, making a difference in the diagnosis and treatment of medical conditions.

5. Purple/Lavender (Spray-coated K2 EDTA added in a plastic tube. So, also called as EDTA tube.)

Accurate results in blood tests are critical in diagnosing and treating medical conditions. To achieve these results, it is necessary to mix the anticoagulant properly with the blood and choose the right tube for the test. In this article, we will examine the benefits of using spray-coated K2 EDTA, the significance of 8 tube inversions, and the impact of tube selection on test accuracy.

The Advantages of Spray-Coated K2 EDTA Anticoagulant

The anticoagulant used in blood tests can greatly impact the accuracy of results. Spray-coated K2 EDTA is a commonly used anticoagulant due to its ability to effectively preserve blood samples and prevent coagulation. This ensures that the sample remains stable, allowing for more precise results.

Eight Tube Inversions for Optimal Mixing

Eight tube inversions are required to ensure that the anticoagulant is mixed evenly with the blood. This process helps to distribute the anticoagulant throughout the sample, leading to consistent results. It is important to perform the inversions carefully to avoid hemolysis and ensure accurate results.

No Clotting Time Necessary

The use of spray-coated K2 EDTA as an anticoagulant has the added advantage of eliminating the need for clotting time. This allows for quicker results, which can be crucial in emergency situations.

Choosing the Right EDTA Tube for Specific Tests

The type of tube used in a blood test can greatly impact the accuracy of results. EDTA tubes, also known as plastic tubes, are specifically designed for tests such as CBC (complete blood count) and PLT count, H&H (hemoglobin and hematocrit), SED rate (eosinophil sedimentation rate), BNP (B-type natriuretic peptide) test, HgbA1C, Cyclosporin, Sickle cell, RETIC (reticulocyte count), Path Review, Intra op PTH, Vancomycin, HIV, Direct Coombs, RBC Folate, PROGRAF, and CD3/CD4. These tubes ensure the stability of the sample and allow for accurate results in these tests.

In conclusion, the proper mixing of anticoagulants and the appropriate selection of tubes are essential in obtaining accurate results in blood tests. The use of spray-coated K2 EDTA anticoagulant, 8 tube inversions, and EDTA tubes can provide consistent and precise results, helping healthcare providers to make informed diagnoses and treatment decisions. By understanding the importance of these factors, we can ensure the best possible outcomes for patients.

6. Pink (Spray-coated K2 EDTA added in plastic tubes)

The Advantages of Spray-Coated K2 EDTA Anticoagulants

Anticoagulants play a critical role in preserving the stability of blood samples and preventing clotting. Spray-coated K2 EDTA anticoagulants are a popular choice due to their ability to maintain the integrity of the sample, leading to more precise test results.

Eight Tube Inversions to Prevent Clotting

Eight tube inversions are necessary to ensure proper mixing of the anticoagulant with the blood. This helps to distribute the anticoagulant evenly and prevent clotting, leading to consistent results. Careful inversions are crucial in avoiding hemolysis and ensuring accurate results.

No Clotting Time Required

The use of spray-coated K2 EDTA anticoagulants eliminates the need for a clotting time, providing quicker results. This can be particularly beneficial in emergency situations.

EDTA Tubes for Accurate Blood Typing and Screening Tests

EDTA tubes, also known as plastic tubes, are designed for specific blood tests, including blood typing and RH, blood typing and screening, antibody screen, crossmatch, and RHOGAM workup. These tubes preserve the stability of the sample, allowing for more accurate results in these tests.

In conclusion, the proper mixing of anticoagulants and the selection of the right tube play a critical role in obtaining accurate results in blood tests. The use of spray-coated K2 EDTA anticoagulants in plastic tubes, 8 tube inversions, and EDTA tubes can provide consistent and precise results, supporting healthcare providers in making informed diagnoses and treatment decisions. Understanding the importance of these factors is key to ensuring the best possible outcomes for patients.

7. Blue (Buffered sodium citrate 0.1-5 M (3.2%) glass and 0.109 M (3.2%) plastic. It is also called as PT tube)

Coagulation testing plays a vital role in the diagnosis and treatment of various medical conditions, including deep vein thrombosis, pulmonary embolism, and bleeding disorders. The choice of anticoagulant and tube can significantly impact the accuracy of test results. In this article, we will examine the benefits of using buffered sodium citrate anticoagulants in PT tubes, the importance of proper mixing, and the role of these tubes in commonly associated tests.

The Advantages of Buffered Sodium Citrate Anticoagulants

Buffered sodium citrate anticoagulants are widely used in coagulation testing due to their ability to preserve the stability of blood samples and prevent clotting. The buffered formula provides a consistent pH balance, leading to more accurate test results.

Proper Mixing with 3-4 Tube Inversions

Proper mixing of the anticoagulant with the blood is essential for accurate test results. Three to four tube inversions are recommended to ensure the anticoagulant is evenly distributed and to prevent clotting.

No Clotting Time Required

The use of buffered sodium citrate anticoagulants eliminates the need for a clotting time, providing quicker results. This is especially beneficial in emergency situations.

PT Tubes for Accurate Coagulation Testing

PT tubes, also known as glass or plastic tubes, are designed specifically for coagulation testing, including PT/INR tests, PTT tests, fibrinogen, d’dimer, and special coag and factor assays. These tubes preserve the stability of the sample and provide consistent and accurate results.

In conclusion, the proper mixing of anticoagulants and the selection of the right tube play a crucial role in obtaining accurate results in coagulation testing. The use of buffered sodium citrate anticoagulants in PT tubes, 3-4 tube inversions, and the avoidance of a clotting time can ensure precise results and support healthcare providers in making informed diagnoses and treatment decisions. Understanding the importance of these factors is essential for ensuring the best possible outcomes for patients.

8. Royal Blue (Plastic tubes is sprayed with K2 EDTA. K2 EDTA increases the MCV (mean corpuscular volume) of RBC in higher concentrations)

Toxicology testing is a crucial aspect of diagnosing and treating patients with potential metal exposure. The use of the right anticoagulant during the blood collection process can greatly affect the accuracy of test results. The additive of choice for toxicology testing is K2 EDTA, which is sprayed onto plastic tubes to ensure proper mixing of the anticoagulant with the blood.

Why K2 EDTA is Ideal for Toxicology Testing

K2 EDTA is an anticoagulant that increases the MCV (mean corpuscular volume) of RBC in higher concentrations, making it the preferred additive for toxicology testing. This anticoagulant ensures that the blood remains in its liquid form, allowing for the accurate determination of trace amounts of metals such as aluminum, cadmium, copper, lead, mercury, selenium, and zinc.

Tube Inversion for Optimal Mixing

During the blood collection process, 8 tube inversions are required to ensure that the K2 EDTA anticoagulant is properly mixed with the blood. This is essential to obtain accurate test results and avoid any potential contamination of the sample.

No Clotting Time Required

Another advantage of using K2 EDTA is that no clotting time is required. This speeds up the blood collection process and allows for quicker results.

Commonly Associated Tests

The use of K2 EDTA additive is recommended for toxicology testing to accurately determine trace amounts of metals. This type of testing is typically performed in a clinical laboratory setting.

Different Types of Tubes and Their Associated Tests

It is important to note that other types of tubes, such as the Gold Top (SST-Serum Separator Tube) and Plain Red Top Tube, should be mixed 5-6 times because they contain a clot activator. However, the Green Top (PST-Plasma Separator Tube) is the preferred choice if listed.

In conclusion, the use of K2 EDTA additive in plastic tubes for toxicology testing is the recommended method for accurate and efficient results. The proper mixing of the anticoagulant with the blood through 8 tube inversions and the lack of required clotting time make K2 EDTA an ideal choice for diagnosing and treating patients with potential metal exposure.

In summary

Color of the Tube	Anticoagulant
Yellow, Pink, and Blue	Sodium polyanethole sulfonate (SPS)
Light Blue “citrate tube”	Sodium citrate (3.2%)
Red	No anticoagulant or additive inside the tube
Green	Heparin (sodium heparin, lithium heparin, or ammonium heparin)
Lavender/Purple “EDTA tubes”	Ethylene-diamine-tetra-acetic-acid
Gray	Potassium oxalate and sodium fluoride

FAQ on Blood Collection Tubes