Which of the following locations should a phlebotomist use to anchor a vein during a venipuncture using the evacuated tube method?

Choice A reason:

Heparin is an anticoagulant, not a clot activator. It works by inhibiting thrombin and preventing the conversion of fibrinogen to fibrin, thus preventing clot formation. It is commonly found in green-top tubes and is suitable for collecting plasma samples for tests like electrolyte levels and coagulation studies.

Choice B reason:

Oxalate is also an anticoagulant that prevents clotting by precipitating calcium. It is not used to promote clot formation but rather to maintain a blood sample in a non-coagulated state for various tests.

Choice C reason:

Citrate functions similarly to heparin and oxalate as an anticoagulant. It chelates calcium ions in the blood, inhibiting the coagulation process. Citrate is often used in blue-top tubes and is ideal for collecting plasma samples for coagulation studies.

Choice D reason:

Silica is a clot activator. It is commonly used in serum separator tubes (SSTs) with a gold or red speckled top. The silica particles provide a surface for the rapid formation of the clot, allowing for the separation of serum from the blood cells. This is essential when serum is needed for testing.

Choice A Reason:
Explaining the procedure to both the parent and the child is crucial. It helps in preparing the child psychologically and ensures that the parent is informed and can provide support during the process. Clear communication can reduce anxiety and make the child more cooperative. It is also a part of informed consent, where the parent understands what the procedure entails and why it is necessary¹².

Choice B Reason:
Choosing not to tell the child when the needle insertion is coming might seem like a way to avoid causing them anticipatory anxiety. However, this approach can lead to mistrust. Children need to be prepared for what to expect, and surprising them can be more traumatic in the long run. It is better to be honest and use age-appropriate language to describe the sensation as a 'quick pinch' or 'poke'¹².

Choice C Reason:
Obtaining a heel stick is a common method for blood collection in infants, particularly newborns, as their veins are not as developed. However, for preschoolers, venipuncture is usually the preferred method because they have more developed veins, and it allows for a larger volume of blood to be collected if needed³.

Choice D Reason:
Obtaining a thumb stick is not a standard practice for blood collection in preschoolers. The thumb has bones and tendons close to the surface, which can increase the risk of injury. The preferred sites are the antecubital fossa of the arm or the back of the hand where the veins are more accessible and there is less risk of hitting bone³.