The Top 5 Phlebotomy Basics to Know

Patient identification

A phlebotomist’s work starts well before a vein is punctured. Our first phlebotomy basic is to make sure you have the right patient in front of you. It happens more often than you could imagine that the wrong patient is drawn due to insufficient patient identification practices. Luckily, the Clinical and Laboratory Standards Institute (CLSI) has a published standard for patient identification.  Firstly, the patient must state and spell their first and last names correctly. Secondly, they must provide you with their date of birth. If the patient’s name, date of birth as well as a facility established unique identifier match the test request information, specimen labels and patient wrist band or photo ID, you are good to go. More information on this crucial issue in the specimen collection process can be found in the CLSI GP33 document [GP33: Accuracy in Patient and Sample Identification (clsi.org)].

Tourniquet application

Once you have identified the right patient, put on your gloves and apply the tourniquet to make the patient’s veins more prominent. To do so, apply the tourniquet above or proximal to the insertion point so that it will not impede the procedure. Then select and clean the appropriate insertion site. The recommended insertion point is the antecubital fossa (area in front of the bend of the elbow). Secondary to this area, the dorsal surface of the hand might be used in certain cases. However, make sure it is applied neither too close nor too far from the planned insertion point. Furthermore, it is also important to apply the right tension on the tourniquet. If the tourniquet is applied too tightly, arterial blood may be prevented from flowing into the area and result in failure to obtain blood.

After having applied the tourniquet correctly, have the patient extend their arm. Make sure the arm is in a downward position to prevent reflux. Our phlebotomy experts suggest that if the patient is not able to make a fist, give them something to hold, for example, a small towel. This might take an extra minute, but it will make the venipuncture easier. However, patients may clench but should not pump their fist. Research has found that fist pumping increases potassium levels and negatively affects the quality of the sample. Causes and Prevention of Pseudohyperkalemia : January 2019 - MedicalLab Management Magazine (medlabmag.com)

Anchoring the vein

Now that you have found the venipuncture site, you will have to anchor the vein before beginning the venipuncture. But how do you correctly anchor a vein? This might seem an odd question: You just pull the skin toward the wrist with your finger, right? However, if anchored incorrectly, blood flow might be impeded. It appears simple, yet which finger you use and where you put that finger can make a difference. Our phlebotomy experts recommend using the thumb of your non-dominant hand. This is a proven way to make sure that your fingers are always behind the needle and helps prevent needle stick injuries during or after insertion. So, anchor the vein your thumb one or two inches below the insertion site to avoid rolling or movement of veins.

Inserting the needle

After all this critical preparation, you are finally ready to draw the patient's blood. If you have correctly followed all preparatory steps, it should be a piece of cake to successfully complete the venipuncture. Still, you should pay special attention to some things during this step. Regardless of the needle you choose - straight or butterfly needle - it is crucial to insert the needle at a shallow angle. CLSI requires the angle between the arm and the needle to be no more than 30 degrees. Basically, your phlebotomy rule of thumb should be: the closer the blood vessel is to the skin surface, the smaller the angle of insertion. For instance, when the puncture site is located on the back of the hand, the needle angle will be close to 10 degrees. This is important to avoid sticking the needle through the vessel. Also, make sure that the needle bevel is in an upward position.

Collection of Evacuated Tubes

The last of our top five phlebotomy basics is correct collection of tubes. To do so, as soon as the needle is inserted in the vein and blood flow is established, loosen the tourniquet and draw the samples. Two aspects while drawing blood are vital for the sample quality: order of draw and draw volume. The tubes are color coded per ISO standards to indicate the additive in the tube for a particular analytical test. To prevent additive carryover (which could lead to possible test result error), it is important to follow the recommended order of draw.

1. Blood culture
2. Blue – Sodium citrate coagulation tube
3. Red or Gold – Serum tubes, including no additive, clot activator or with/without gel
4. Green – Heparin tube with or without gel
5. Lavender – EDTA tube with or without gel separator
6. Grey – Sodium fluoride / potassium oxalate glycolytic inhibitor

When drawing your samples, remember that every tube is pre-evacuated. This means that the tube’s vacuum will automatically pull in the ideal amount of blood for the appropriate blood to additive ratio. Once the vacuum is exhausted, the blood flow will stop. This is your signal to move on to collect the next specimen. Filling tubes to the manufacturer's indicated volume (marked on each tube) is crucial for the additive to work as planned. If a tube is not filled to capacity, the ratio of blood to additive will be compromised and may lead to possible test result error. After you have filled all the relevant tubes and mixed with the appropriate number of gentle inversions, end the venipuncture procedure. To do so, remove the last tube from the needle/holder, put gauze over the site without applying pressure and remove the needle. Activate the safety feature according to the manufacturer's instructions – for some products this might be even while the needle is still in the vein. Once removed, apply pressure on the insertion point. Before leaving the patient, label tubes according to facility policy and reconfirm patient identification.

We know drawing blood is not as simple as it seems. Despite the regulations and techniques that must be learned, every patient is different and presents unique circumstances for specimen collection. Still, if you follow our phlebotomy experts’ top five phlebotomy basics, you will put best practices into action that help to assure sample quality and appropriate patient care. If you want to learn more about certain aspects of the blood collection, we recommend reading through these blogs: NMIE0716_Cover_Puneet.indd (nursingcenter.com) and Phlebotomy Basics For Nurses (rn-journal.com)

At Greiner Bio-One, we work closely with phlebotomists to provide the highest-quality equipment on the market. Contact us for more information about our products and services.