It is preferred that the majority of laboratory blood tests are performed on venous blood obtained by venipuncture. There are certain occasions however, when blood cannot or should not be obtained by venipuncture and capillary blood collection is the only viable alternative.
Capillary blood collection and testing is preferable on neonates, infants and young children due to lack of appropriate veins and a reduced blood volume of the patient. Venipuncture should be avoided due to the risk of complications, such as clots, infection, damage to surrounding tissues, damage to infant from holding while performing venipuncture, hemorrhage, reflex arteriospasm, gangrene of an extremity, etc. Regardless of the collection method, care needs to be taken when collecting from such patients, because anemia and cardiac arrest could occur if too much blood is drawn.
In adult patients, capillary blood is used for testing when any of the following conditions occur:
- Damaged veins
- Fragile veins(geriatric patients)
- Thrombotic tendencies
- To obtain blood for point-of-care testing (POCT)
- No available veins due to intravenous lines (IVs) in both extremities