Effects of Clotting on the Capillary Blood Sample

How to Subscribe
MLS & MLT Comprehensive CE Package
Includes 135 CE courses, most popular
$95Add to cart
Pick Your Courses
Up to 8 CE hours
$50Add to cart
Phlebotomy CE Package$55Add to cart
Individual course$20Add to cart
The page below is a sample from the LabCE course Pre-analytical Challenges Encountered with Capillary Blood Collection and Testing. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about Pre-analytical Challenges Encountered with Capillary Blood Collection and Testing (online CE course)
Effects of Clotting on the Capillary Blood Sample

To obtain the best capillary sample for testing, care must be taken to avoid clotting. Because clotting starts immediately after the skin is punctured, clotting is the greatest challenge in collecting a good capillary sample. The first drop of blood contains interstitial fluid which in turn contains tissue thromboplastin. Tissue thromboplastin is released as soon as the skin is broken and tissue penetrated, as a first step in the coagulation cascade. Therefore, the first drop of blood should be wiped away with sterile gauze.
If platelet clumps are formed during collection, test results will be inaccurate or erroneous. Tests such as complete blood counts (CBC) will be affected. Also, small clots can block the instrument's aspiration probes or tubing, which in turn can cause delay in testing and unscheduled maintenance.
The healthcare provider performing the capillary puncture should work quickly to avoid the formation of microclots. Completion of capillary blood collection should be under two minutes.