Avoiding pre-analytic errors

Avoiding pre-analytic errors

How to avoid errors when collecting capillary blood samples

• Before puncture¹, cleanse site with alcohol and allow to ‘air dry’ to avoid haemolysis of sample; do not wipe site dry
• After puncture, use clean gauze to wipe away the first drop of blood to avoid specimen dilution with interstitial fluid^1,2
• Touch collection device to second drop of blood and allow blood to flow into blood collection tube by capillary action, using a gentle squeeze-and- release technique to ensure a steady blood flow and prevent haemolysis and unwanted blood clots in specimen²
• Do not squeeze the finger too hard or use a scraping or scooping motion when collecting the blood to help avoid haemolysis and specimen dilution with interstitial fluid^1,2

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. WHO guidelines on drawing blood: best practices in phlebotomy. World Health Organisation; 2010.

2. 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..

Achieving adequate capillary blood sample volume

Choosing the right safety lancet for the volume of blood required

• The volume of capillary blood required to perform a test varies, depending on the test type and testing instrumentation
• Safety lancets have varying needle gauges and puncture depths and are designed to produce a range of blood volumes necessary for different tests
• The volume of blood that can be expected from a safety lancet of given gauge and depth specification will vary from patient to patient
• In general, the greater the device needle diameter and puncture depth, the greater the volume of blood produced for testing¹
• There are many factors that influence the blood volume produced from any given sampling episode; these include patient hand temperature, safety lancet specification and post-puncture massage technique²

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. Fruhstorfer H, Muller T, Scheer E. Capillary blood sampling: how much pain is necessary? Part 2: Relationship between penetration depth and puncture pain. Prac Diab Int 1995; 12: 184-185.

2. Grady M, Pineau M, Pynes MK, Katz B, Ginsberg B. A Clinical Evaluation of Routine Blood Sampling Practices in patients with Diabetes: Impact on Fingerstick Blood volume and pain. Journal of Diabetes Science and Technology 2014; 8 (4): 691-698. * For example, a 30-gauge (30G) needle is thinner than a 21-gauge (21G) needle and would, therefore, be used for taking smaller volume blood samples See instruction sheet ‘Collecting a finger capillary blood sample’