Preanalytical Errors in Medical Laboratories

1. Preanalytical Errors in Medical Laboratories Ashishkumar Soni QMS Manager – West Randox Laboratories India Pvt. Ltd.

2. Objectives • Identify the significant pre-analytical errors that can occur during blood specimen collection and transport • Explain the various means of pre-analytical error prevention • List proactive steps to reduce potential pre-analytical errors associated with blood collection and transport

3. Total Quality Laboratory Quality means achieving positive patient outcomes through control of pre-analytical, analytical, and post-analytical error.

4. There are a variety of potential errors that can affect the quality of the laboratory results. • Pre-analytical errors • Before the sample reaches the laboratory • Analytical errors • During the analysis of the sample • Post-analytical errors • Occurring after the analysis

5. Introduction • Three phases of laboratory testing: Pre-analytical, Analytical and Post-analytical Now termed as Pre Examination,Examination & Post Examination (As per ISO 15189) • Pre-analytical : Test order by clinician, Instruction to the patients, Specimen collection, Storage, Transport and processing (for eg. Centrifugation) • Analytical : Testing • Post-analytical : Retesting- if required, Results Transmission, Interpretation, follow-up,.

7. Pre-analytical errors • Pre- and post-analytical errors are estimated to constitute 90% of errors • Errors at any stage of the collection, testing and reporting process can potentially lead to a serious patient misdiagnosis • Errors during the collection process are certainly inevitable and can be prevented with a diligent application of quality control, continuing education and effective collection systems

8. Types of Preanalytical Errors • Patient Identification • Phlebotomy Technique • Collection Procedures • Specimen Transport • Specimen Processing

9. Pre - Analytical Errors…Before the sample reaches the laboratory but directly affect the quality and clinical usefulness of the final result. Improper preparation of the patient:- • patient fasting • glucose test • stress and anxiety • urinary protein

10. Pre - Analytical Errors… • Improper preparation of the patient • Improper collection of the blood sample:- • sample haemolysis • LDH, potassium or inorganic phosphate • insufficient sample volume • unable to carry out all requested tests • collection timing • 24 hour urine

11. Pre - Analytical Errors… • Improper preparation of the patient • Improper collection of the blood sample • Incorrect specimen container:- • serum or plasma • fluoride tubes for glucose • to inhibit glycolysis • EDTA unsuitable anti-coagulant for calcium

12. Pre - Analytical Errors… • Improper preparation of the patient • Improper collection of the blood sample • Incorrect specimen container • Incorrect specimen storage:- • sample left overnight at room temperature • falsely elevated K, Phos and red cell enzymes • delay in sample delivery • falsely lowered levels of unstable analyte (NEFA)

13. The sex of the patient male or female The age of the patient new born / juvenile / adult / geriatric Dietary effects low carbohydrate / fat high protein / fat When the sample was taken early morning urine collection pregnancy testing Patient posture urinary protein in bed-ridden patients Other Factors…

14. Effects of exercise creatine kinase / CRP Medical history heart disease / diabetes / existing medication Pregnancy hormonal effects Effects of drugs and alcohol liver enzymes / dehydration Other Factors…

15. Patient Identification Errors in correctly identifying the patient are indefensible • Reasons for patient identification errors : • Patient identification from identification bracelet (inpatients) • Proper positive patient identification procedures not followed • Patient identification by asking patients to state or spell their full name (inpatients/outpatients) • Patient identification by staff or family member if patient unable to identify him/herself

16. Patient Identification Specimen tubes unlabeled Requisition or collection tube labels not affixed to tubes • Requisition or collection tube labels in bag containing collection tubes • Requisition or collection tube labels rubber-banded to tubes • Collection tube labels not affixed to all tubes • Specimen collection tubes labeled insufficiently with at minimum patient’s full name, date/time of collection, phlebotomist’s initials

17. Patient Identification Collection tubes labeled with the wrong patient • Wrong computerized labels affixed to collection tubes at bedside • Collection tubes not labeled at the time of collection • Collection tubes incorrectly labeled by someone other than the phlebotomist who collects the specimen

18. Phlebotomy Errors • Phlebotomy is a highly complex skill requiring expert knowledge, dexterity and critical judgment • Phlebotomy errors may cause harm to patients (For eg. Thrombosis) or result in needle-stick injury to the phlebotomist

19. Phlebotomy Technique • Phlebotomy technique is important • Ensures test result validity • Minimizes trauma to patient • Minimizes potential for phlebotomist injury • Reduces recollections • Vein selection essential for successful venipuncture • Three veins in antecubital fossa in order of selection (1) median cubital (2) cephalic (3) basilic

20. Venipuncture site selection • Although the larger and fuller median cubitalvein of the arm is used most frequently, cephalic and basilic veins are also acceptable for venipuncture.

21. Phlebotomy Technique • Site Selection • Use alternative arm or draw below IV to avoid contamination/dilution from IV • Avoid sites with IV • Document arm if IV • Mastectomy—avoid site due to lymphostasis • Infection risk/alteration in body fluids and blood analytes • Edematous areas —avoid due to accumulation of body fluids • Possible contamination/dilution of specimen

22. Phlebotomy Technique • Venous Access Difficulties • Obstructed, hardened, scarred veins • Veins difficult to locate • Use of Alternative sites • Top of hand/Side of wrist • Areas to avoid • Vein Collapse • Use of appropriate needle size • Smaller evacuated collection tube

23. Phlebotomy Technique • Tourniquet Application • Tourniquet tied too close to the venipuncture site can cause hematoma • Veins may not become prominent if tourniquet is tied too high (more than 3 to 4 inches above venipuncture site) • Tourniquet left on longer than one minute can result in hemoconcentration, affecting some test results • Tourniquet should be released as soon as needle is in the lumen of the vein and blood flow established

24. Phlebotomy Technique • Cleansing of venipuncture site • Thorough cleaning with alcohol • Allow alcohol to dry completely to avoid stinging sensation upon needle entry and hemolysis of sample • Samples such as blood cultures should be collected using iodine to cleanse site to ensure sterility of sample • Recollection rate for blood cultures ranges due to contamination is as high as 50% in hospitals with increased costs, patient overtreatment

25. Phlebotomy Technique • Correct collection system • Evacuated tube system (Vacutainer) for large veins in antecubital fossa • Syringe for small, fragile veins or veins outside antecubital fossa • Venous access • Needle entry should be at 15 to 30 degrees angle depending on depth of vein • Needle entry should be in same direction as vein, centered over vein • Anchor vein to prevent movement during needle entry and to reduce pain to patient

26. Collection Procedures • Order of Draw • Order of draw affects the quality of the sample and can lead to erroneous test results due to contamination with the additive from the previous blood collection tube • Hemolysis • Blood collected insufficient to amount of additive in tube (Ratio of anticoagulant to Blood) • Traumatic venipuncture • Blood collected from area with hematoma • Vigorous shaking of tubes after collection • Milking the site when collecting capillary samples and blood collected using a small diameter needle.

27. Order of Draw for Multiple Tube Collections • 1. Blood culture containers • 2. Blue top tubes • 3. Red top tubes • 4. Green top tubes • 5. Lavender top tubes • 6. Gray top tubes

28. Red • No anticoagulant present • Tests using serum which include: most blood chemistries, serology tests.

29. Light Blue • Additive - Sodium Citrate • Tests: Coagulation studies - PT, PTT, fibrinogen, etc. • MUST BE FILLED COMPLETELY.

30. Lavender Top Tube • Additive =EDTA (Ethylene Diamine Tetra Acetic Acid) • Hematology

31. Green • Sodium heparin, lithium heparin or ammonium heparin. • STAT blood chemistries.

32. Gray • Additive: • Potassium oxalate and sodium fluoride. • or Na2 EDTA and sodium fluoride. • Glucose.

33. Blood Cultures • Not for routine laboratory analysis, special collection to detect bacteria growing in blood. • Site preparation VERY important.

34. Collection Procedures • Timing of Collection • Timed Draws • Therapeutic Drug Monitoring • Peak and trough collection times • Basal State Collections • Fasting requirements—no food or liquid except water • Specimens affected by time of day, for example, cortisol

35. Collection Procedures • Improper collection tube drawn for test ordered Example - No gel tubes should be used for collection of drugs testing • Collection tube not completely fille • Example—light blue top tube for Coagulation Studies. Incomplete filling results in specimen dilution and erroneous Prothrombin and aPTT test results.

36. Collection Procedures • Capillary Collections (Finger stick or heel stick) • Appropriate site • Heel stick—sides of the bottom surface of the heel • Finger stick—third or fourth fingers, perpendicular to fingerprint lines on fleshy pads on finger surface • Warm before collection to increase capillary blood flow near skin surface • Cleanse site with alcohol and allow to air dry

37. Collection Procedures Capillary Collections • Massaging site to increase blood flow • Milking site can cause hemolysis or tissue fluid contamination • Finger sticks—roll fingers toward fingertip at 1st finger joint several times • Heel sticks—gently squeeze infant’s heel before performing puncture. • Perform puncture while firmly squeezing finger or heel • Wipe away first two drops of blood • Ensure that full blood drop wells up each time

38. Collection Procedures Capillary Collections • Avoid touching capillary collection tube or micro collection tube to skin or scraping skin surface • Contaminates puncture site • Blood may become hemolyzed • Mixing micro collection tubes with additive frequently to avoid micro clots • Collecting tubes with additives first • Protecting tubes for bilirubin from light

39. Transportation Transport of blood specimens in the proper manner after collection ensures the quality of the sample • Timing • Some specimens must be transported immediately after collection, for example Arterial Blood Gases. • Plasma for coagulation tests must be seperated within 30 mins of collection • Specimens for serum or plasma chemistry testing should be centrifuged and separated within two hours

40. Transportation • Temperature • Specimens must be transported at the appropriate temperature for the required test • On ice—ABGs, Ammonia • Warmed -98.6 degrees (37 C) for cryoglobulins • Avoid temperature extremes if transported from via vehicle from other collection site • Transport Container • Some samples need to be protected from light, for example, bilirubin • Transport in leak-proof plastic bags in lockable rigid containers

41. Processing • Centrifugation Right speed & time very imp to avoid hemolysis • Storage Even after testing is done, many times samples are required for rechecks, or test edition / addition • Pre-treatment of Samples Required for tests like HbA1c, G6PD etc Best procedure is to follow manufacturer’s guidelines

42. Error Prevention • Phlebotomy Education • Phlebotomists should have completed a standard academic course in phlebotomy and undergo thorough on-the-job training under the supervision of a senior phlebotomist • Continuing Education • Phlebotomists should participate in regular educational competency assessments (written and observational) • Phlebotomy resources • Adequate staffing to maintain collection standards • Use of vaccutainers & barcodes

43. Conclusion • Good quality assurance vital for the laboratory to reduce errors and ensure confidence in patient results • Implementation of a good laboratory quality assurance package, while appearing to represent additional costs to the lab’s budget will in the long run: • Decrease lab cost by eliminating need to run unnecessary additional tests! • Decreased cost of running entire hospital by preventing inappropriate patient care!

44. Let’s Discuss • How are pre-analytical errors prevented in your laboratory? • What technology do you use to prevent human error? • What systems does your laboratory use to prevent errors by non-laboratory staff collecting blood? • What pro-active improvements would reduce the number of pre-analytical errors?

45. Thank you for your Kind Attention Golden Rule of Clinical Laboratory Science “No result is better than a wrong result.”