Proper equipment selection and use are vital for maintaining sample viability and ensuring the accuracy and reliability of diagnostic results. Understanding the tools and materials involved in blood collection is fundamental to achieving successful outcomes and upholding patient safety. Before we delve into the specific equipment and its use at the bedside, let’s consider the environment in which the procedure is undertaken. This is summarised below in Figure 1.2.
The first consideration is the environment where the blood sample is drawn. It is imperative that the area be clean, spacious, and comfortable for all involved, ensuring the patient’s privacy throughout the procedure. This consideration extends to adequate access to cleaning facilities, with essentials like soap and water readily available. These measures are vital in providing a conducive environment for blood collection, ultimately contributing to the overall success of the diagnostic process.
Patient comfort is paramount in the blood collection process. It is crucial to have a suitable chair or bed that not only allows the patient to sit upright but also provides the flexibility to recline them in case of fainting or discomfort. Equally important is the inclusion of an armrest to facilitate comfortable blood collection from the patient’s arm. Moreover, the comfort of the operator is not to be overlooked. A key aspect of patient care is ensuring that the healthcare professional is positioned comfortably to collect the sample safely.
The importance of equipment sterility in venepuncture and blood collection cannot be overstated. These procedures carry significant risks, notably needle stick injuries, which can lead to potential infections. Utilising sterile equipment is fundamental in minimising these risks. This is achieved through the use of gloves, skin disinfectants like alcohol swabs, and single-use equipment, which are standard practices in maintaining sterility.
Equipment used Directly in the Venepuncture Procedure
Procedure Tray
The procedure tray plays a critical role in the blood collection process. Keeping this tray clean and sterile is essential, as it holds all the necessary equipment, ensuring that it is kept away from the patient and out of harm’s way. The tray also facilitates the safe transportation of sharps and other hazardous materials. Many procedure trays are designed with a dedicated area for disposing of sharps, further enhancing safety protocols (Figure 1.3).
Figure 1.3 - Procedure tray with integrated sharps bin
Gloves
The importance of using gloves cannot be understated. They must be disposable and single-use. This practice is not only a standard in maintaining hygiene but also crucial in preventing cross-contamination and ensuring the safety of the patient and the healthcare professional. Typically, non-sterile gloves are used while ensuring they are latex-free to minimise the risk of allergic reactions for the healthcare professional and the patient. However, sterile gloves are used where blood is drawn from central venous catheters to prevent the introduction of microorganisms into the bloodstream due to the high-risk nature of the procedure.
Tourniquet
A tourniquet is wrapped around the patient’s arm to enhance venous filling and increase venous distension, effectively locating the vein and facilitating needle insertion. They should ideally be for single use. Reusing tourniquets has been discouraged due to the heightened risk of infection (reference). A study¹ highlighted the importance of single-use products, especially tourniquets, to prevent transmitting bacteria or other infectious agents to patients. At the start of every day, hospital phlebotomists were supplied with a fresh sterile tourniquet. After use, the tourniquets were swabbed and cultured, revealing a 25% contamination rate with methicillin-resistant Staphylococcus aureus (MRSA). This study underscored the impact of poor hand hygiene practices among healthcare professionals. Following hand decontamination education, the rate of tourniquet contamination was significantly reduced.
Needles
A needle is used to puncture a vein, usually in the arm, to draw blood for testing or administer medications, fluids, or other treatments directly into the bloodstream. The needle’s sharp, bevelled tip allows for a smooth entry into the vein with minimal discomfort to the patient while ensuring efficient and effective access to the vascular system.
The choice of needle is a critical factor in blood collection procedures. The needle must be appropriately sized for both the patient and the procedure. By ‘size,’ we are referring to the gauge, or diameter, of the needle. This diameter is often indicated by a colour-coded system on the needle with the higher the gauge number, the smaller the needle’s diameter (Figure 1.4).
High-gauge, fine needles are typically used in paediatric settings since paediatric patients have fine and often inconspicuous veins. Conversely, larger lower-gauge needles are employed when larger volumes of blood are required, such as in apheresis procedures. It is important to note that this colour coding is not universally standardised. Therefore, referring to the product specifications for accurate gauge identification is crucial.
Beyond standard needles, butterfly needles, easily recognisable by the plastic ‘wings’ on either side, are also used (Figure 1.5). Depending on the product, these needles are connected to a flexible tube, which can be made of rubber or plastic. The tubing ends with a connector, allowing for the attachment of other equipment. The connectors often comprise the Luer lock system, ensuring secure, leak-free connections between different medical equipment parts.
Figure 1.5 - An example of a bufferfly needle
Regarding safety features, many needles come equipped with safety clips. After use, these clips can be engaged to cover the needle’s sharp end, minimising the risk of injury to both the operator and the patient.
Blood Tubes
While glass tubes were common in the past, we now predominantly use plastic tubes. This shift has made the tubes more resilient, particularly during transport and post-collection processes like centrifugation. There is also a generally accepted universal colour-coding system for blood collection tubes, indicated by the cap colour. Figure 1.7 below summarises the main types of blood collection bottles utilised in clinical practice, categorised by the cap colour, the anticoagulant or additive each contains, and the specific laboratory tests typically performed with each bottle type. For most haematology blood tests, the purple and blue top bottles are most commonly used.
EDTA-ethylenediaminetetraacetic acid, ESR-erythrocyte sedimentation rate, FBC-full blood count, INR-international normalised ratio, SST-serum separator tube.
For the purple or lavender top bottle, ethylenediaminetetraacetic acid (EDTA) is the anticoagulant used to inhibit the coagulation process. This is crucial because it halts the coagulation process by binding calcium ions, preserving the morphology of blood cells. This bottle type is primarily used for various tests, including the full blood count, blood film, reticulocyte count, and erythrocyte sedimentation rate. It is also used for tests investigating haemoglobinopathies, HbA1c measurements for diabetic control, and various tests for blood-borne parasites, including malaria.
Figure 1.8 - Purple-top EDTA sample tube
Figure 1.9 - Blue-top citrate sample tube
The blue-top bottle contains sodium citrate, an anticoagulant. This sample bottle is primarily used in coagulation laboratories for investigations like a coagulation profile, which includes prothrombin, activated partial thromboplastin times, and Clauss fibrinogen level. Other investigations include the international normalised ratio (INR), D-dimer, and specific factor assays.
For the purple or lavender top bottle, ethylenediaminetetraacetic acid (EDTA) is the anticoagulant used to inhibit the coagulation process. This is crucial because it halts the coagulation process by binding calcium ions, preserving the morphology of blood cells. This bottle type is primarily used for various tests, including the full blood count, blood film, reticulocyte count, and erythrocyte sedimentation rate. It is also used for tests investigating haemoglobinopathies, HbA1c measurements for diabetic control, and various tests for blood-borne parasites, including malaria.
Figure 1.8 - Purple-top EDTA sample tube
Clinical Waste Bin
The clinical waste bin is an essential component in maintaining a safe and hygienic environment during blood collection procedures. These bins are specifically designed to safely dispose of biohazardous materials, including used needles, gloves, gauze, and other items contaminated with blood or bodily fluids. Clinical waste bins are typically divided into sharps and non-sharps bins. Sharps bins are used for disposing of needles, lancets, and other sharp instruments to prevent injury and cross-contamination. Non-sharps bins are intended for items like gloves, cotton balls, and bandages. It is crucial to ensure that these bins are easily accessible in all areas where blood collection takes place and that they are clearly marked and regularly emptied by trained personnel.
Figure 1.11 - Clinical sharps bin
Alcohol Swab
An alcohol swab is a small, pre-soaked pad containing isopropyl alcohol used to disinfect the skin before venepuncture. The swab is crucial for ensuring sterility at the puncture site, thereby reducing the risk of introducing microorganisms into the bloodstream.
Gauze/cotton
Gauze or cotton is used immediately after the needle is withdrawn from the vein to apply pressure to the puncture site. This application helps to stop bleeding, prevent haematoma formation, and promote clotting at the needle entry point. It is important to use sterile gauze or cotton to avoid infection.