Preparation for blood tests: what can go wrong before the sample reaches the lab.

Many errors can occur in the pre-analytical phase of laboratory testing, such as during patient preparation, sample collection, handling, storage and transport. Minimisation of errors during this phase is key to optimising the usefulness of laboratory tests and may reduce the need for repeat sampling. Various patient factors can affect laboratory test results, including posture, fasting status, circadian variation, medications and other interfering agents. Clinicians should be aware of these factors and advise patients on the necessary preparation before testing. Patient identification, collection timing, haemolysis, contamination and sample volume are important considerations when collecting and handling a sample. Individuals should consult their local laboratory for specific test instructions or protocols, as these can vary.