SPECIMEN COLLECTION

• Venipuncture

  • The act of obtaining a blood sample from a vein using a needle attached to a syringe or a stoppered evacuated tube.
  • It is the most common way to collect blood specimens.
• H pattern is displayed by approximately 70% of the population
• Types of Blood Specimens

  • Serum
  • Plasma
  • Whole Blood
• Serum

  • normally a clear, pale yellow fluid
• Serum

  • non-fasting serum can be cloudy due to lipids.
  • separated from clotted blood by centrifugation (approximately 10 minutes at an RCF of 1,000-2,000g)
• Plasma

  • normally a clear to slightly hazy, pale yellow fluid
• Plasma

  • separates from the cells when blood in an anticoagulated tube is centrifuged.
  • contains fibrinogen
• STAT and other tests

  • requiring a fast turn around time (TAT) are often collected in tubes containing heparin anticoagulant because they can be centrifuged immediately to obtain plasma.
• Whole Blood

  • consists both cells and plasma
• Whole Blood

  • must be collected in an anticoagulant tube to keep it from clotting
  • used for most hematology tests and many point of care tests (POCTs), especially in acute care and stat situations.
• Methods of Venipuncture

  • Evacuated Tube Systems
  • Needle and Syringe
  • Butterfly Set
• Evacuated Tube System

  • preferred method because blood is collected directly from the vein into a tube, minimizing the risk of specimen contamination and exposure to blood.
• Needle and Syringe

  • discouraged by CLSI due to safety and specimen quality issues
• Butterfly Set

  • can be used with the ETS or a syringe
  • often used to draw blood from: infants and children , hand veins , in other difficult-draw situations
• Tourniquet

  • restrict venous flow but not arterial flow
• Needles

  • gauge and bore are inversely related
• Gauge, Needle type, Typical use:

  15-17, Special needle attached to collection bag; collection of donor units

  18, Hypodermic; Used primarily as a transfer needle

  20, Multisample Hypodermic; Sometimes used when large-volume tubes are collected

  21, Multisample Hypodermic; Considered the standard venipuncture

  22, Multisample Hypodermic; Used on older children and adult patients

  23, Butterfly; Used on the veins of infants and children
• The color coding of needles indicates the gauge.
• The gauge of the needle is inversely related to the size of the needle, the larger the gauge number, the smaller the needle bore and length
• 21-gauge needle

  • considered the standard for venipuncture
• 23-gauge needle

  • used for children
• 23 or 25 gauge

  • is used for winged infusion set (butterfly)
• 23-gauge butterfly

  • most commonly used for small difficult veins
• 25-gauge

  • used by specially trained personnel to collect blood from scalp or other tiny/small veins of premature infants and other neonate
• Needle length:

  • 1 inch or 1.5 inches - 21 to 23 gauge
  • 1/2 to 3/4 inch - butterfly needle
• Evacuated Tube System 3 basic componnets

  • Multisample Needle
  • Tube Holder
  • Evacuated Tubes
• Syringe System

  • Includes a plastic syringe, a needle and a transfer device
• Butterfly system

  • 23 gauge is the most commonly used for phlebotomy
• Evacuated tubes

  • Tubes sealed with a partial vacuum inside by rubber stoppers.
  • Vacuum is artificially created by pulling air from the tube.
  • The amount of vacuum is measured precisely by the manufacturer so that the tube will draw the exact volume of blood indicated on the label.
• Evacuated tube additive

  • Different blood tests requires different types of blood specimens
  • Most tubes have additive called anticoagulants
  • The amount of additive in a tube has been calibrated by the manufacturer.
• Anticoagulant

  • to prevent clotting of blood sample
  • The color of the stopper on each tube indicates what, if any, anticoagulant the tube contains.
• Evacuated Tubes

  • Red top
  • Gold top
  • Light blue top
  • Green top
  • Purple/Lavender top
  • Gray top
  • Black top
  • Brown/tan top
  • Yellow top
• Other tubes:

  • Pink
  • White
  • Light green/black
  • Royal blue
• Red top

  • No additive In glass tube
  • Clot activator in plastic/ Hemogard tube (Mechanism of Action: Silica Clot Activator)
• Red top Test

  • Routine Blood Chemistry
  • Serology tests
  • Blood Bank procedures.
• Gold top

  • Clot activator
  • Gel separator (Mechanism: Silica Clot Activator)
• Gold top Test

  • Routine Blood Chemistry
  • Diagnostic testing of serum for infectious disease.
  • HLA typing
• Light Blue top

  • Sodium Citrate
  • Chelates/ Binds Calcium
  • Thrombin and Soybean Trypsin
  • Fibrin Degradation Products
• Light Blue top Test

  • Plasma/ Coagulation
  • Prothrombin time
  • APTT
  • D-dimer
  • Fibrinogen
• Green top

  • Sodium/ Lithium Heparin
  • Inhibits thrombin formation