Pediatric Capillary Collection with Hemolysis Risk
A 2-year-old child needs a capillary blood sample for a complete blood count and glucose. The phlebotomist plans to perform a fingerstick. The child's fingers are cold, and the mother reports the child has been crying and moving. The phlebotomist warms the child's hand with a warm pack for 3 minutes, then cleans the fingertip with alcohol and immediately performs the puncture. The blood flow is slow, so the phlebotomist squeezes the finger firmly to obtain enough blood. The sample is collected in a microtainer and sent to the lab. The lab calls to report hemolysis and a glucose result that is 20% lower than a previous venous sample.
1. Identify at least three preanalytical errors in this capillary collection and explain how each could contribute to hemolysis or inaccurate glucose results.
Read the worked answer
- Inadequate warming: The hand was warmed for only 3 minutes; recommended warming is at least 3-5 minutes to arterialize the blood. Cold fingers can cause vasoconstriction, reducing blood flow and increasing the risk of hemolysis when squeezed.
- Alcohol not allowed to dry: Cleaning with alcohol and immediately puncturing can cause hemolysis and dilution of the sample with alcohol, leading to inaccurate glucose results.
- Excessive squeezing: Firm squeezing of the finger forces tissue fluid into the sample, diluting the blood and causing hemolysis. Hemolysis falsely lowers glucose results because glucose is consumed by red cells during hemolysis.
- Fingerstick in a child: For children under 1 year, heelstick is preferred; for toddlers, fingerstick is acceptable but the lateral aspect of the finger should be used to avoid nerve endings. The site selection may not have been optimal, but the main errors are warming, alcohol drying, and squeezing.
2. What should the phlebotomist have done differently to ensure a quality capillary sample?
Read the worked answer
The phlebotomist should have:
- Warmed the child's hand for at least 3-5 minutes to ensure good blood flow.
- Cleansed the puncture site with alcohol and allowed it to air dry completely before puncture.
- Used the lateral side of the fingertip (avoiding the center) to reduce pain and nerve damage.
- Avoided excessive squeezing; instead, applied gentle intermittent pressure proximal to the puncture site.
- Collected the blood in the appropriate microtainer, filling it adequately and mixing gently to avoid hemolysis.
- Considered the child's age: for a 2-year-old, fingerstick is acceptable, but heelstick is preferred for infants under 1 year.
- Ensured the child was calm and warm to promote blood flow.