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Key Points on Blood Testing Procedures

May 1, 2025

Special Considerations and Point of Care Testing

Special Procedures

  • Most lab tests use blood from venipuncture or capillary puncture.
  • Some tests require special collection procedures or other body fluids (e.g., feces, urine).

Blood Bank Specimens

  • Provide information for safe blood transfusions.
  • Strict protocol to prevent fatal transfusion errors.

Specimen Requirements

  • Collect lavender or pink-top EDTA tubes; sometimes use nonadditive red-stoppered tube.

Identification & Labeling

  • Extremely strict to prevent errors.
  • Required labels include patient's full name, hospital ID, DOB, collection date/time, phlebotomist’s initials.

Special Identification Systems

  • Use special blood bank ID systems like PDC Securline, Typenex Medical’s barcoded bands, and Siemens Patient Identification Check.

Type, Screen, and Cross-Match

  • Determine blood type (ABO) and Rh factor.
  • Crossmatch checks compatibility of patient plasma/serum with donor RBCs.

Blood Donor Collection

  • Purpose is to collect blood for transfusions.
  • Donor Blood Banks regulated by FDA.

Donor Eligibility

  • Age: 17–66 years.
  • Weight: At least 110 pounds.
  • Requires medical history, physical exam, written consent, and confidentiality.

Principles of Donor Unit Collection

  • Use large antecubital vein.
  • Equipment: sterile needle, blood bag with anticoagulant.

Blood Cultures

  • Diagnose bloodstream infections like bacteremia or septicemia.
  • Requires special collection procedures.

Special Collection Requirements

  • 2–4 blood cultures recommended.
  • Skin antisepsis critical to prevent contamination.

Antimicrobial Neutralization Products

  • FAN bottles contain activated charcoal.
  • ARD bottles contain resin.

Coagulation Specimens

  • Use sodium citrate tubes.
  • Proper 9:1 blood-to-anticoagulant ratio needed for accuracy.

Glucose Tests

  • 2-Hour Postprandial Glucose Test: Screens for diabetes.
  • Glucose Tolerance Test: Diagnoses carbohydrate metabolism issues.
  • Lactose Tolerance Test: Diagnoses lactose intolerance.

Paternity Testing

  • Determines probability of biological fatherhood.
  • Involves ABO/Rh typing and DNA profiling.

Therapeutic Drug Monitoring

  • Ensures drug levels are effective but non-toxic.
  • Timing of peak and trough levels is critical.

Therapeutic Phlebotomy

  • Used to treat conditions by withdrawing blood.

Toxicology Specimens

  • Detect toxins/poisons in various specimens.
  • Chain of custody is important.

Point-of-Care Testing (POCT)

  • Brings lab testing to the patient for convenience and fast results.
  • Must comply with CLIA and OSHA guidelines.

Quality and Safety

  • POCT results must match central lab tests.
  • Continuous monitoring ensures quality.

Waived vs. Nonwaived Tests

  • Waived tests require less stringent QC.

Electronic Quality Control (EQC)

  • Detects instrument issues but not specimen handling errors.

Arterial Blood Gases and Electrolytes

  • Arterial puncture is more hazardous than venipuncture.
  • ABG Tests: Measure pH, PaCO₂, PaO₂, etc., for respiratory evaluation.

Personnel and Site Selection

  • Performed by trained medical personnel.
  • Sites include radial, brachial, femoral arteries.

Arterial Puncture Hazards

  • Includes arteriospasm, nerve damage, hematoma, etc.

Sampling Errors

  • Air bubbles, delay in analysis, improper mixing, and obtaining venous blood can cause errors.