5.2 Special Collections II & Special Populations

Neonatal and Pediatric Collections

Infants and small children require modified technique. Their total blood volume is small, their veins are fragile, and excessive removal can cause iatrogenic anemia. For most routine tests on a newborn, a capillary heelstick is preferred over venipuncture.

Heelstick Technique and Sites

The safe puncture zone is the medial or lateral plantar (bottom) surface of the heel. This avoids the calcaneus (heel bone) and the nerves and tendons at the back of the heel.

Do not use the central arch of the foot (nerve, tendon, and cartilage injury risk) and do not puncture a previous site (infection and scarring). Excessive squeezing ("milking") causes hemolysis and tissue-fluid contamination.

Newborn Screening

Newborn screening (NBS) tests every baby for inherited metabolic and genetic disorders (such as phenylketonuria, hypothyroidism, and sickle cell disease) using a filter-paper card (often called a Guthrie card).

• Collect after the infant is at least ~24 hours old (per state protocol) for valid results.
• Touch the heel drop to the center of a printed circle and let blood soak through to fill the entire circle from one side in a single application.
• Do not layer multiple drops, apply blood to both sides, or touch the paper with gloves, hands, or the heel.
• Air-dry the card horizontally, away from heat and direct sunlight, before sending.

Bilirubin in Newborns

Neonatal bilirubin evaluates jaundice and risk of brain injury (kernicterus). Two handling rules dominate the exam:

1. Protect from light. Bilirubin breaks down on light exposure, which falsely lowers the result. Use amber tubes or wrap the tube in foil and deliver promptly.
2. Collect quickly and minimize hemolysis, which interferes with measurement.

Peripheral Blood Smears

A peripheral blood smear spreads a thin film of blood on a glass slide so cell morphology can be examined under a microscope (used for anemias, leukemias, and parasites such as malaria).

• Prepare the smear from EDTA (lavender-top) blood within about 1 hour of collection, or make it directly from a fingerstick drop, to preserve cell shape.
• A good smear has a smooth feathered edge with no holes, ridges, or streaks.
• Allow the slide to air-dry; do not blow on it.
• Label the frosted end with patient identifiers per facility policy.

Blood Donor Collection and Therapeutic Phlebotomy

These are large-volume collections performed under specific rules.

Volunteer (Allogeneic) Blood Donation

• A standard whole-blood unit is about 450-500 mL collected into a bag containing an anticoagulant-preservative such as CPDA-1 (citrate-phosphate-dextrose-adenine).
• A large-bore needle, typically 16-18 gauge, is used to allow rapid flow and protect red cells.
• Donors complete a health history and mini-physical (hemoglobin, blood pressure, pulse, temperature) and must meet weight and interval eligibility (commonly at least 110 lb and an 8-week interval between whole-blood donations).
• The phlebotomist performs an aseptic scrub of the antecubital site similar to a blood culture prep to keep the unit sterile.

Autologous Donation

Autologous donation is when a patient donates their own blood before a scheduled surgery to be transfused back to themselves, eliminating transfusion-reaction and bloodborne-disease risk.

Therapeutic Phlebotomy

Therapeutic phlebotomy is the removal of blood as treatment, not for testing or transfusion to others. It requires a provider order and is used for:

The technique resembles a donor draw (large-bore needle, ~500 mL unit), but the blood is typically discarded rather than transfused, and the procedure follows a physician's order and protocol.

Point-of-Care Testing (POCT)

Point-of-care testing (POCT) is laboratory testing performed at or near the patient (bedside, clinic, ED) with portable analyzers, giving rapid results.

Common POCT examples include blood glucose meters, hemoglobin/hematocrit, activated clotting time, blood gases, and rapid strep or pregnancy tests. Key exam points:

• POCT still requires correct patient identification, technique, and documentation.
• Devices need scheduled quality control (QC) checks and calibration; do not run patient samples if QC fails.
• Capillary glucose by meter is a screen; abnormal or critical values are confirmed by the central lab.
• Operators must be trained and competency-documented; POCT is regulated under CLIA (Clinical Laboratory Improvement Amendments).