hematology

• skin puncture- technique of choice to obtain blood specimen from the ff:

  • newborns and pediatric
  • extremely obese patients
  • elderly patients with fragile veins
  • patienst whose veins are reserved for therapeutic purposes
  • severely burned patients
• puncture site:

  adult- palmar surface of the non dominant hand, 3rd or 4th finger

  children (<1 yr old)- plantar surface of medial (toe) or lateral (little toe)
• depth of incision in skin puncture:

  adult: 2.0-2.5 mm

  infants: <2 mm
• avoid applying pressure/squeezing/milking of the site cause it can cause:

  • hemolysis
  • introduce excess interstitial fluid
• order of draw of skin puncture:

  1. tube for blood gas
  2. Slides
  3. EDTA microtainer
  4. Other additive microtainer
  5. Serum microtainer
• warming of the puncture site can increase the bloodflow sevenfold. the site can be warmed using warm washcloth (40-42C) for no longer than 3-5 mins
• most common antiseptic is 70% isopropyl alcohol
• most common sites for venipuncture is the superficial veins of the antecubital fossa
• in venipuncture, cleanse the site using friction scrub with movement of back and forth. distance: 3-4 inches above the venipuncture site
• two anatomical patter of venipuncture site/veins: H and M pattern
• veins to be used (in order preference):

  1. median
  2. cephalic
  3. basilic
• angle between the needle and the skin is <30 degrees.
• tourniquet application:

  length of time: <1min or 60 secs

  effects of prolonged tourniquet application:

  • hemolysis
  • hemoconcentration
  • shortened coagulation times
• EDTA- purple/Lavender top- most routinely used in hema determination

  (8x inversion) -action is chelating of calcium. prevents platelet aggregation.
• EDTA cuase swelling of platelets (causes approximately 20% increase in MPV during the first hour). should be based on EDTA specimens that are between 1-4 hrs old.
• insufficient EDTA: overfilled tube ; presence of clots

  excessive EDTA: underfilled tube ; dec in HCT and ESR, degenerative changes in WBC and RBC and increase PLT
• ORDER OF DRAW:

  1. Blood culture- yellow- 8x inversion
  2. citrated tube- light blue - 3-4x inversion
  3. Serum tube- red- glass (no additive)- 0x plastic (clot activator) 5x
  4. Heparin- green- 8x inversion
  5. EDTA- lavander- 8x
  6. Sodium flouride- gray- 8x inversion