What are the steps involved in the venepuncture process?
Always wash your hands using the correct procedure prior to touching your patient, donning gloves and taking blood. The Aseptic Non–Touch Technique (ANTT) approach should be used and has been shown to significantly improve the aseptic technique of healthcare workers and reduce the numbers of Healthcare Associated Infections.

When locating a vein, you should tie your disposable tourniquet around the lower deltoid region (around 4–5 finger widths above the venepuncture site) to allow the veins to stand out. When looking for a vein, you’re feeling for a nice bouncy, juicy vein, which is visible or palpable under the skin situated within the antecubital fossa area. Sometimes clients can present with very tricky veins and need to have blood taken from their hand. However, it is advised that you are trained on conducting venepuncture in this area if you have not taken blood from the hand before.

Once you are satisfied you have an adequate vein to conduct venepuncture, ensure to use an 70% alcohol wipe to decontaminate the skin and then allow to dry for 30 seconds.  When the skin is dry, anchor the vein below the puncture site and you are now ready to insert your gauge needle. 

When piercing the skin, make sure to insert the needle at a 30-degree angle or less and ensure that the bevel of the needle is facing upwards to allow a gentle piercing. Once the needle has been inserted into the vein, attach the blood tube to allow the blood to flow through the line and into bottle. When you have retrieved enough blood, retract the needle, and dispose immediately into a sharps box. Don’t forget to add pressure to the site with cotton wool or gauze to reduce bleeding or bruising at the site. Ask the patient to hold this in place, and ensure bleeding has stopped before a plaster is applied.

What factors should be considered when choosing needle gauge sizes in venepuncture?

When deciding on the appropriate needle gauge to use for venepuncture, a few factors should be considered to ensure the client is as comfortable as possible when obtaining a successful blood sample.

Client’s Vein Size:

You should assess the size and condition of the client’s veins first. I have known veins to be large and supple, moving sidewards as I pierced the skin with the needle, causing me to miss the vein. I have seen veins of a larger, more juicy size to bruise easier than other prominent, smaller veins. Sometimes, in my experience, I have found that a blue gauge needle (23G) allows the vein to remain in position and reduces bruising than if I was to use a green gauge needle (21G). However, everyone is different, and it depends on your intuition, if you have attended the venepuncture course and are confident to carry out venepuncture in a safe way.

Client’s Age:

We should consider the client’s age. If we are carrying out venepuncture on an infant or a young child, a small gauge needle should be used as they will have smaller veins. Older adults may have fragile, less prominent veins and a smaller gauge needle may also be preferable. Hydration plays an important role in successful venepuncture. It is always advised that the client drink plenty of fluids before venepuncture to ensure enough blood is obtained.

Patient’s Medical Conditions:

Always check with the client first, to see if they have any medical conditions before carrying out venepuncture. Your client may be living with a condition and is taking certain medications, which can impact how we conduct venepuncture. For example, does the client have a history of deep vein thrombosis and takes warfarin? If so, this can cause them to bleed more than usual, and they can bruise quite easily after venepuncture. Patients with haemophilia or clotting disorders may require a larger needle to ensure adequate blood flow into the blood bottle. It is always a good idea to apply extra pressure to the area with cotton wool or gauze, to reduce bleeding or bruising at the site after venepuncture is complete.

Required Blood Sample:

We should consider the volume and the type of blood sample that is required during venepuncture. For example, if testing a client for Tuberculosis infection, it is wise to use a standard straight needle and blood vacutainer to obtain the sample as air will not need to be expelled and we can acquire the sample straight away. However, if we were to use a butterfly needle, we would have to prime the line before obtaining a sample, which takes time and can make the client feel more anxious.

Being aware of what is more comfortable for the client if they are nervous or stressed is paramount in choosing the right needle gauge during venepuncture. So, in this instance, I would say a standard straight needle and blood vacutainer would be beneficial as you don’t have to prime the line and you can get your blood sample into the bottles straight away, limiting the amount of time venepuncture is being conducted and reducing the amount of anxiety the client may experience.

Needle Penetration Depth:

The depth of needle penetration is also an important factor. If a client has superficial veins, a small needle gauge would be beneficial, whereas a larger needle gauge would be ideal for deeper veins to reach the required depth.

Finding Confidence When Choosing the Correct Size Gauge Needle for Venepuncture

When conducting venepuncture, it is important to use good clinical judgement and consider the above factors when selecting the appropriate needle gauge for each client. Regular communication with the client and monitoring their comfort before, during and after obtaining your blood sample, is crucial to carrying out a successful and safe venepuncture technique. Keeping up to date with your venepuncture learning and development is also crucial to improving your skills and will allow you to follow the latest guidance surrounding venepuncture practices.

Written by David E Griffiths