PMLS MIDTERM EXAMINATION

• Syringe method


  Older venipuncture procedure that is not used very often due to greater risk of needle-stick injuries
• Evacuated method


  Preferred method of blood collection today

  
• Syringe system is sometimes used for patients with small or difficult veins

  
• Parts of the needle-syringe system


  • Syringe needles
  • Syringe barrel and plunger
  • Additional parts

  
• Hypodermic needle


  Syringe needles used for phlebotomy procedures are generally gauges 21 to 23, in 1- or 1.5-in. lengths
• Syringe needles


  Must have a resheathing feature to allow it to be safely covered and removed
• Syringe sizes


  Routine blood collection: 5ml, 10ml

  
• Syringe transfer device


  Allows the safe transfer of blood into the tubes without using the syringe needle or removing the tube stopper

  
• Syringe transfer device


  • Greatly reduces the chance of accidental needlesticks
  • Confines any aerosol or spraying of the specimen that may be generated as tubes are removed from it

  
• Syringe method vs evacuated tube system

  Syringe plunger is used to create a vacuum that draws blood into the syringe barrel, unlike the evacuated tube system which has a pre-existing vacuum

  
• If the needle is too large for the vein it will tear the vein and cause bleeding (hematoma)
• If the needle is too small it will damage the blood cells during sampling, and laboratory tests that require blood cells or hemoglobin may be invalid
• Unsafe practices are also observed when using the syringe method since needle sticks are far more possible compared to the evacuated tube system
• Pros of syringe method

  • Controlled aspiration of blood
  • You can change the needle gauge for smaller/thinner veins
  • Easily maneuvered
  • Cheap

  
• Cons of syringe method

  • The volume of syringe used limits the fluid dispensing volume
  • Excessive resistance may lead to the build-up of pressure and eventual failure of the syringe pump
  • Needle pricks
  • Time consuming in transferring blood from one tube to another

  
• The use of a syringe transfer device is also a crucial step in blood collection, and improper usage may then affect the quality of blood samples

  
• Order of draw


  • Sterile tube (blood culture)
  • Blue-top coagulation tube
  • Serum tube (with or without clot activator, with or without gel)
  • Heparin tube (with or without gel plasma separator)
  • EDTA tube
  • Glycolytic inhibitor tube
• Evacuated tube system


  Closed system of sample collection, making it the preferred method
• Components of evacuated tube system

  • Multi-sample needle/ two-way needle
  • Tube holder/ adapter
  • Evacuated tubes
• Evacuated tubes


  Air-evacuated creating a vacuum, once inserted in the vein the vacuum serves to collect a specific amount of blood

  
• Reasons for following an organized order of draw

  • Carryover/cross-contamination
  • Tissue thromboplastin
  • Microbial contamination
  • Interference with assay
  • Removal of constituents
  • Effect on enzyme action
  • Alteration of cellular constituents
• Carryover/cross-contamination


  The transfer of additive from one tube to the next, occurs when blood in an additive tube touches the needle during ETS blood collection or when blood is transferred from syringe into ETS tubes

  
• Tissue thromboplastin contamination


  Substance present in tissue fluid, activates the extrinsic coagulation pathway and can interfere with coagulation tests
• Microbial contamination


  Blood culture tubes or bottles are sterile and are collected first in the order of draw to ensure sterility and prevent contamination
• Interference with assay


  The additive may contain a substance that is the same or reacts in the same way as the substance being measured
• Removal of constituents


  The additive may remove the constituent to be measured
• Effect on enzyme action

  The additive may affect enzyme reactions
• Alteration of cellular constituents

  An additive may alter cellular constituents
• Color-coded tubes


  • Sterile tube
  • Coagulation tubes
  • Serum tubes (with or without clot activator/gel)
  • Heparin tubes (with or without gel plasma separator)
  • EDTA tubes
  • Pearl/white top: plasma preparation tubes
  • Glycolitic inhibitor tubes
  • Thrombin-based tubes
  • Special collection tubes
• Sterile tube


  Tests: Blood culture, Additive/s: Sodium polyanethol sulfonate, Number of inversions: 8 - 10 times, Specimen: Whole blood
• Coagulation tubes


  Tests: Coagulation tests, Additive/s: Sodium citrate (3.2% or 3.8%), Number of inversions: 3 - 4 times, Specimen: Whole blood
• CTAD tube


  Contains sodium citrate, theophylline, adenosine and dipyridamole, Minimizes in vitro platelet activation and the artificial entry of platelet factors into plasma
• 3.2% sodium citrate is CLSI recommended for coagulation tests on patients with polycythemia or hematocrit reading greater than 55%
• 1. 1 ratio of blood-to-anticoagulant should be maintained
• AD TUBE WITH A LIGHT BLUE HEMOGARD CLOSURE

  Specialized platelet testing tube
• Contains


  • Sodium citrate
  • Theophylline
  • Adenosine
  • Dipyridamole
• AD TUBE WITH A LIGHT BLUE HEMOGARD CLOSURE

  • Minimizes in vitro platelet activation and the artificial entry of platelet factors into plasma
• SPECIAL BLUE STOPPER


  Provides serum for determinations of certain fibrin degradation products
• THROMBIN AND SOYBEAN TRYPSIN INHIBITOR


  Providing serum for determinations of certain fibrin degradation products
• 3.2% SODIUM CITRATE is CLSI recommended for COAGULATION TESTS on patients with POLYCYTHEMIA OR HEMATOCRIT reading greater than 55% which requires that the anticoagulant to be DECREASED due to the rationale that if there is an EXCESS SODIUM CITRATE, it will INTERFERE WITH COAGULATION TESTS