Poorly venepunctured blood samples can dramatically affect the results of a test. Some of the more common errors are listed below:
- Insufficient sample – appropriate volume blood tubes are supplied with. Insufficient samples will mean an inability to test and delay in results and provision of blood products.
- Haemolysed sample - if the blood sample has been venepunctured using needle and syringe and a small gauge needle is used to pierce the lid of the Vacutainer tube, haemolysis may occur especially if the blood is forced into the tube by pushing the plunger. Vacutainer tubes contain a vaccuum that will naturally draw sufficient blood into the tube. Change to a wider gauge needle before piercing the Vacutainer lid. Haemolysis will prevent the sample from being tested as assays are light transmission dependant and haemolysis in the plasma will give false positive results.
- Samples delayed in transit – Delays in receipt of the sample in Blood Bank will mean a delay in testing and as a result delay in provision of blood products. Significant delays of may mean the sample is no-longer suitable for testing.
- Clotted samples – Samples not taken directly into the Vacutainer and mixed sufficiently may clot. Once clotted the red cells cannot be tested for the blood group and the sample will be unsuitable for testing.
- Blood grouping.
- Red cell antibody screening and antibody identification.
- Red cell phenotopying.
- Compatibility testing.
- Direct antiglobulin test.
- Kleihauer (estimation of foetal-maternal Haemorrhage).
- ABO Titres
If a transfusion reaction is suspected, stop the transfusion immediately. Follow the trust protocol (internal users only) and inform blood bank. All units which have been used (partially and fully) must be returned to the blood bank along with:
Storage and Wastage of Blood
It is essential that blood and blood products are stored correctly to minimise any adverse incidents from occurring:
- Blood must only be stored in authorised blood refrigerators
- Blood transfusions should be commenced no longer than 30 minutes from the time the unit was taken from the Blood fridge.
- Fresh Frozen plasma must be used within 4 hours of thawing if stored at room temeparture or within 24 hours if stored in an authorised blood fridge.
- Platelets should be kept agitated in Blood Bank until ready for use.
Avoidable wastage of blood and blood products will generate a 'Wastage Report' for the ward to complete and return to Blood Bank. This is monitored by the Hospital Transfusion Committee.