Why does the lab fail blood sample?

Occasionally, the lab may be unable to analyse all the biomarkers included in a blood test panel. Finger prick tests have a higher failure rate due to the lower volume of blood, however we provide clear instructions and a few tips on how to successfully complete a finger prick sample. 

There are 5 main factors that can contribute to a failed sample: 

Haemolysis 

A haemolysed sample occurs when red blood cells rupture, releasing haemoglobin into the surrounding plasma.  This can occur due to improper collection, handling, or storage of the sample. Haemolysis can distort the results of various blood tests as the release of haemoglobin can interfere with measurements of certain biomarkers.

Insufficient Sample 

The laboratory will centrifuge the sample which separates the elements suspended in the plasma (red blood cells, white blood cells and platelets). If there is not enough blood collected to perform the necessary tests (inadequate sample volume), the lab will be unable to run the test accurately.  

Please note that in some cases the lab is still able to do a partial analysis of the sample. If this is the case, you will receive these results. In other cases, however, they are not able to analyse the sample at all. 

The Sample is too old 

If a sample is delayed in the post, it may be too old to be used for testing when it arrives at the lab.  Some biomarkers are more sensitive and less stable than others.  We try to limit the time your sample spends in the post which is why we strongly recommend sending samples on Monday to Thursday, avoiding Friday, weekends and public holidays.  We provide a tracked postage returns label. 

If your sample is not labelled correctly 

If your patient’s sample is not labelled or there is information missing the lab will reject it in accordance with UKAS guidelines.  Working to strict UKAS guidelines the labs must produce accurate medical records, and a sample without a completed label is not permissible.