Resources
Blood Sample Integrity: Collection to Lab
How collection technique and handling affect a blood sample between the draw and the laboratory.
A result is only as good as the sample behind it. Many laboratory errors happen before the sample reaches the analyser, during collection, labelling, handling and transport. A haemolysed sample can give a misleading potassium result; a clotted EDTA sample cannot be used for a full blood count, and the patient has to be bled again.
Getting it right starts before the needle is uncapped. Confirm the patient’s identity with at least two identifiers, usually full name and date of birth. Check the request, choose the right tubes and fill them in the correct order of draw, and confirm any special requirements such as fasting or timed collection. The order of draw exists to stop additives carrying over from one tube to the next.
Technique matters during the draw. Leaving the tourniquet on too long concentrates the blood and can distort some results. Shaking tubes damages red cells. Tubes with anticoagulant need gentle inversion straight after filling, and citrate tubes for clotting tests must be filled to the line because the ratio of blood to anticoagulant affects the result.
After collection, samples need the storage conditions and delivery time the receiving laboratory specifies. Some analytes change quickly at room temperature, some must be protected from light, and a few need to be kept cold or warm. Mobile phlebotomists face this more than most, so suitable transport bags and a clear handover plan matter.
Laboratories record why samples are rejected: haemolysis, clotting, too little blood, labelling errors, transport delays. A phlebotomist who keeps a note of their own rejected samples and the reasons has a practical way to improve.
Frequently Asked Questions
Why does the order of draw matter?
It stops additives carrying over between tubes. For example, EDTA carried from a lavender tube into a serum tube can give a falsely high potassium and a falsely low calcium. Filling tubes in the standard order avoids this.
How long can a sample wait before it reaches the laboratory?
It depends on the test and the laboratory. Some samples are stable for hours at room temperature; others need to be processed quickly or kept cold. Follow the receiving laboratory’s requirements, and ask them if there is going to be a delay.
Related Resources
Book blood draws for your patients
Lola Dispatch is an invitation-only platform for healthcare businesses. Tell us about your service and we will be in touch.