Capillary Collection
What type of blood (venous vs arterial) is more present in capillary samples when the site is warmed?
Arterial blood proportion increases.
Why are microcollection tubes color-coded?
To indicate which additive or anticoagulant they contain
What percentage of lab errors occur in the preanalytical phase?
More than half (over 50%)
Why is venipuncture more challenging in pediatric patients than adults?
Smaller size, lower blood volume, and higher anxiety levels
What condition can be caused by prolonged or blind probing with a needle?
Nerve damage
What is the depth range for dermal puncture in premature infants?
.65-.85 mm
What is the maximum blood volume microcollection containers can hold?
Up to 750 μL.
Name one lifestyle factor that may alter test results.
Alcohol use
exercise
dehydration
altitude
What is the main purpose of neonatal screening tests?
Early detection of inherited metabolic disorders
What is one sign of collapsed veins during venipuncture?
Loss of blood flow / vein flattening against the needle.
Why should the skin puncture site be warm, healthy, and free of scars or calluses?
To reduce risk of poor flow, hemolysis, or sample contamination.
Why are retractable blade lancets important for safety?
To prevent accidental needle sticks and meet OSHA requirements.
Why are bariatric chairs useful in outpatient phlebotomy?
Provide comfort and safety for obese patients
Why should rewards (stickers, toys) be available for pediatric patients?
To reduce fear/anxiety and encourage cooperation
What is the correct response if blood refluxes into an anticoagulant tube?
Reject specimen
Why are capillary samples sometimes unsuitable for repeated testing?
Reference values differ from venous blood, and tissue fluid can alter results.
Which puncture sites are avoided because of risk of bone injury?
Fingers of infants under 1 year
What patient condition requires physician’s permission before drawing blood from the foot or leg?
Diabetes or anticoagulant therapy
What physical skin change in geriatric patients increases risk of bruising?
Decreased collagen / thinner skin
What complication may occur if excessive pressure is not applied after draw?
Compartment syndrome or hematoma
What special precautions must be taken when collecting bilirubin samples?
Protect from light (amber tube or foil wrap) to prevent false results.
Why is specimen overfilling especially risky in anticoagulant-containing microtubes?
Alters blood-to-additive ratio, leading to inaccurate results.
Why is documentation of the antiseptic used during site prep important?
To explain abnormal results
Why is parental presence sometimes discouraged during a child’s blood draw?
It can increase the child’s anxiety instead of reducing it
Why must IV fluids be paused before drawing blood near an IV site?
To prevent dilution and inaccurate lab results.