Sampling with larger blood volumes
Capillary blood sampling versus venepuncture
Choosing an appropriate sampling method
- Venous blood (obtained by venepuncture) is the specimen of choice for most routine laboratory tests; most laboratory reference ranges are based on venous blood
- Capillary blood sampling may be indicated for paediatric patients where small, but adequate, amounts of blood for laboratory tests can be easily obtained using optimum collection techniques1
- Capillary blood specimens can be advantageous in paediatrics, elderly, severely burned, those with thrombotic tendencies, extremely obese, apprehensive patients and those performing tests at home1
- The smaller volume of blood obtained by capillary sampling is easier to manage in clinics, home settings and remote areas where on-site testing provides quick results for patient diagnosis (Point of Care Testing)1
- Sample type should be taken into account when evaluating results: differences in venous and capillary blood are generally minor, but clinically important differences in some analyte concentrations have been reported1*
There are three different types of blood: arterial (the blood in the arteries), venous (the blood in the veins) and capillary (the blood in the capillary beds, a mixture of arterial and venous blood, obtained by capillary blood sampling)
These materials have been produced in consultation with key opinion leaders and follow global guidelines, but the user should use his or her professional judgement when using any technique or method described in these materials and should take into account all applicable national, regional and institutional guidelines and regulations.
1. Clinical and Laboratory Standards Institute (CLSI) document GP42-A6 (former H04-A6): Procedures and Devices for the Collection of Diagnostic Capillary Blood Specimens; Approved Standard – Sixth Edition. Clinical and Laboratory Standards Institute; Wayne, Pennsylvania, USA: 2008.
* Statistically and/or clinically important differences in the concentrations of glucose, potassium, total protein and calcium have been reported1.
† Venepuncture in children is often difficult and potentially hazardous; the larger amount of blood removed may pose a danger to children, especially those who are anaemic1. Puncturing deep veins in children may cause painful haematoma, haemorrhage, venous thrombosis, infection, damage to surrounding tissues and other complications1.