Capillary Blood Collection

• Capillary blood collection


  Collection of blood from the capillary beds, typically using a lancet to puncture the skin
• Methods of blood collection

  • Arterial puncture
  • Venous puncture
  • Capillary puncture
• Capillary puncture

  • Preferred for newborns, adult patients with difficult venous access, point-of-care testing, glucose testing
• Benefits of capillary puncture

  Minimally invasive, requires small volume of blood, quick and convenient
• Limitations of capillary puncture

  Specimen volume may not be sufficient for all tests requested, high risk of specimen hemolysis and/or clotting
• Layers of the skin

  • Epidermis
  • Dermis
  • Hypodermis (Subcutaneous tissue)
• Epidermis

  Thinnest layer of the skin, composed of dead skin cells
• Dermis

  Contains the hair follicles, sweat glands, and sebaceous glands
• Hypodermis (Subcutaneous tissue)

  Blood vessels or capillaries is found, called the capillary bed
• Preferred sites for capillary puncture

  • Lateral plantar surface of the heel (newborns)
  • Palmar surface of the middle and ring finger (adults)
  • Earlobes (least preferred)
• Equipment for capillary puncture

  • Lancets
  • Microtainer Tubes
  • Microhematocrit tubes
  • Blood gas equipment
• Microtainer Tubes

  At most, they can contain 1 ml of blood
• Steps in capillary puncture

  1. Introduce yourself and explain your purpose

  2. Properly identify and prepare the patient

  3. Sanitize hands, put on gloves, and prepare equipment

  4. Position patient and select puncture site

  5. Warm the site, if applicable

  6. Fill and mix the tubes in order of draw

  7. Place gauze pad and apply pressure

  8. Label specimen and observe special handling instructions

  9. Dispose used contaminated materials

  10. Check the patient before leaving
• Preferred lancet length


  1.75 mm
• Depth of incision


  For infants: >2.0 mm, for adults: <2.5 mm
• Distance of bone or cartilage from skin surface

  1.5 - 2.4 mm