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SOURCES_OF_ERROR_IN_MEDICAL_LABORATORY_INVESTIGATIONS_Copy.pptx

This document outlines sources of error in medical laboratory investigations and ways to prevent them. It classifies errors into pre-analytical, analytical, and post-analytical phases. Pre-analytical errors, such as issues with test ordering, sample collection, handling and storage, account for about 75% of total errors. Common causes include improper patient preparation, use of incorrect test or sample type, and mishandling of samples. Both controllable factors like technician technique and non-controllable factors like patient physiology can influence pre-analytical errors. The document also discusses analytical errors from instrument issues and post-analytical errors in results reporting. Overall it emphasizes that preventing laboratory errors requires effort across

Health & Medicine◦
SOURCES OF ERROR IN MEDICAL LABORATORY INVESTIGATIONS AND IT’S PREVENTION PRE-ANALYTICAL ANALYTICAL POST-ANALYTICAL by JAMES A. HODEY 27TH JUNE, 2023 1
OUTLINE • INTRODUCTION • CLASSIFICATION OF PRE-ANALYTICAL VARIABLES • OVERVIEW OF VARIABLES, THEIR EFFECTS AND CORRECTIVE ACTIONS • ANALYTICAL ERRORS • POST ANALYTICAL ERRORS • CONCLUSION • REFERENCES 2
INTRODUCTION 1/4 • Medical Laboratory Service plays a pivotal role in; diagnosis, clinical decision making, patient management and follow-up, surveillance and disease control, planning, monitoring and evaluation, and budgeting. • Laboratory practice is divided into 3 phases (pre-analytical, analytical and post-analytical) all targeted for quality improvement. • Total testing process begins with test Ordering, Reporting of test results up to clinical decision making, these encompasses the 3 phases. 3
INTRODUCTION 2/4 4
INTRODUCTION 3/4 • Laboratory errors as defined by Bonini et al. is “a diagnosis that is missed, wrong, or delayed, as detected by some subsequent definitive test or finding”. • This has been further acknowledged and adopted by the ISO technical report 22367, • as “ a defect occurring at any part of the laboratory cycle, from ordering test to reporting, interpreting and reacting to results”. 5
INTRODUCTION 4/4 • Among the phases, pre-analytical errors currently accounts for about 75% of all the errors (Lippi et al; Plebani and Carraro et al). • Sadly, most activities in the pre-analytical phase is neither performed entirely in the clinical laboratory nor under the control of laboratory personnel, hence difficult to monitor and improve. • Most laboratories often leave pre-analytical activities to other health care personnel who have little to no formal training in Medical Laboratory practice. 6
CLASSIFICATION OF PRE-ANALYTICAL VARIABLES • Pre-analytical processes includes all steps that occur from test ordering until right before sample analysis. • Pre-analytical variables is classified into: Controllable factors Non-controllable factors 7
CONTROLLABLE FACTORS • Request and test sample factors • Physiological factors Posture/Recumbency Circadian variations Physical fitness, exercise and Training Travels • Lifestyle factors  Food and fasting state Diet Herbal preparations Recreational substances Stimulants Drugs and medications 8
NON-CONTROLLABLE FACTORS • Age • Sex • Race • Environmental • Medical conditions / co-morbidity 9
REQUEST AND TEST SAMPLE FACTORS 1/2 • Test ordering • Patient identification • Patient preparation • Site selection and preparation • Tourniquet Application and time • Venipuncture Technique • Use of appropriate sample bottles • Order of draw 10
REQUEST AND TEST SAMPLE FACTORS 1/2 • Right / appropriate specimen • Right / appropriate sample tube(s) • Correct specimen volume • Proper sample Handling and specimen processing • Serum or plasma samples • Centrifugation/ sample separation • Proper handling of blood samples • Stability and storage for whole Blood, serum/plasma, stool, urine, CSF, Swabs, etc. • Proper packaging and transport of specimen. 11
TEST ORDERING • Filling of test request form. Test requisition form should contain a min. of patient’s name, age, sex, Hospital number, location, Prescribers name and contact, clinical diagnosis and brief clinical information including any initial treatment. • Ordering of wrong test. This could be due to:  Confusion over tests with similar names (such as 25- hydroxyvitamin D vrs 1,25- dihyroxyvitamin D). Transcription errors and misinterpreted verbal orders, which occurs when physicians do not place test orders themselves. 12
Sample of Information on Request forms in March Provided Not Provided Name 100 0 (0%) Sex 84 16 (16%) Age 82 18 (18%) Folder No. 16 84 (84%) CR No. 46 54 (54%) Diagnosis 14 86 (86%) Prescriber’s Name 71 29 (29%) Prescriber’s Signature 67 33 (33%) 0 20 40 60 80 100 120 Graphical Presentation Provided Not Provided 13
CORRECT SAMPLE BOTTLE AND SAMPLE VOLUME • Use of appropriate sample bottle as indicated for the test to be carried out. • Collect adequate sample quantity as labelled on tube, unless in peculiar situations ,e.g. neonates. • Use of the appropriate tube e.g pediatric tubes for neonates and babies. • Order of Draw; • Blood culture • Serum tubes • Heparin tubes • EDTA tubes • Fluoride oxalate tubes 14
PROPER SAMPLE HANDLING AND SPECIMEN PROCESSING • No vigorous shaking of blood samples, avoid hemolysis. • Gently rock blood tube to mix with anticoagulant. • Samples collected into one type of tube should never be transferred into another tube. • If blood collection site is distant from the laboratory, specimen should be collected into evacuated tubes containing thixotropic polymer gel and should be centrifuge on site. • The gel forms an effective barrier between the separated serum/plasma and cells, so that no leakage of cellular constituent into the supernatant above the gel. 15
RIGHT SPECIMEN FROM APPROPRIATE SITE • Plasma allows for more rapid processing of specimen for clinical test. • But anticoagulants may interfere with some analytical methods E.g. K+ and phosphate. • Type of urine specimen needed for different tests vary. • Early morning urine for UPT and microscopic examination of cells, • Fresh urine for cytology, • Collection of 24hrs urine for quantitative measurement, • Mid-stream urine for c/s • Terminal urine for S. haematobium. 16
PHYSIOLOGICAL FACTORS 1/2 Prolong bed rest can dramatically affects body constituents. • Plasma volume and ECF vol. decrease within few days • Hematocrit increase by up to 10% . • Creatinine kinase increases from muscle release. • Plasma protein concentration reduces. • Protein- bound constituents decreases. • Serum potassium, reduces by 0.5mmol/L. • Hydrogen ion excretion decreases. 17
PHYSIOLOGICAL FACTORS 2/2 • Calcium: Hypercalcemia, hypercalciuria , from bone resorption • The amplitude of circadian variation of cortisol is reduced with prolonged immobilization. • As a result some hospitalized patients should be delay certain tests until after they leave the hospital and resume normal activity. • When an individual becomes active after a period of bedrest, longer than 3 weeks is required before calcium balance is achieved. 18
LIFESTYLE DIET: • Plasma urea conc. doubles, within 4 days of change of diet to high protein diet, along with increase in urinary excretion. Serum cholesterol, phosphate, urate and NH3 conc. also increases concomitantly. • A high fat diet increases serum TG conc., but depletes the nitrogen pool because of nitrogen requirement for excretion of ammonium ions to maintain acid- base homeostasis. • A high carbohydrate diet decreases the serum concentrations of LDL- cholesterol, triglycerides, cholesterol and protein. 19
FOOD AND FASTING STATE • Food ingestion is a significant source of pre- analytical variability. This effect varies based on analyte and time between meal ingestion and blood collection. • e.g, glucose and TGs significantly increases after meals with high carbohydrates and fat respectively. • An overnight fasting period of 10 to 12 hours prior to blood collection is optimal for minimizing variations. • Glugacon and insulin secretions are stimulated by protein meal, and insulin alone is stimulated by carbohydrate meal. 20
DRUGS • Opiates– increases pancreatic enzymes • Oral contraceptives– reduces HDL and increases LDL • Thiazides – Hypokalemia, hyperglycaemia, hyperuricemia, prerenal azotemia, increased LDL- Chol, total- Chol and TGs • Phenytoin - Reduces calcium and phosphate conc. (with risk of osteomalacia), increases ALP activity and induces synthesis of Bilirubin conjugating enzymes in the liver. • Also causes hyperglycemia and glycosuria. 21
VENDOR SELECTION AND PROCUMENT • Vendor qualification and selection • Inspection of vendor premises for conditions of Storage, Packaging and transport of reagents and consumables. • Use of GSA and FDA approved products • Pre testing and validation of samples (before award and acceptance during delivery) • Verification, Stores receipt and acceptance • Storage conditions in facility and stock taking • Laboratory structural design and work flow 22
CORRECTIVE ACTION • Correct and adequate information on request. • Proper client preparation prior to sample collection. • Education on proper sample tubes, order of draw and blood to anticoagulant ratio. • Proper sample storage, packaging and transport. • Introduction and education on Sample acceptance and rejection criteria manual. • Development and introduction to laboratory handbook. • Laboratory's advice is sort and adhered to during procurement. 23
ANALYTICAL ERRORS 1. Systemic error- indicates poor accuracy  Poor calibration  Incorrect procedure  Wrong standard 2. Random errors- indicates poor precision  Pipetting error  Incorrect sample numbering  Transcript error  Reader fluctuation 2. Inherent errors  Power fluctuations  Machine precision errors 24
POST ANALYTICAL ERRORS 1.Data entry errors. 2.Hand written results 3.Verbal miscommunication of results 4.Reporting delays 5.Lapse in communicating critical results 6.Report issued but not used for immediate clinical dicision 25
CONCLUSION • Prevention of laboratory errors is a shared responsibility, starting from the client, relations, prescribers, nurses, laboratory staff, stores and procurement, administration, accounts, orderlies and all health workers. • Actions to control laboratory error is a journey. • Never relax or overlook it. • Enjoy analyzing and implementing CAPA. • This is the only way for continuous quality improvement for better patient care. 26
REFERENCES • Tietz Clinical Chemistry and Molecular Diagnostics, 5th Ed. • Bishops Clinical Chemistry- Principles, Techniques, Correlations, 7th Ed • Bonini P, Plebani, Cerrioti F, Rubboli F. Errors in Laboratory medicine. Clin. Chem 2002:48:691-8. • Carraro P, Plebani M. Errors in stat laboratory Types and frequencies 10 years later. Clin Chem 2007:53:1338-42. • Young DS. Effects of pre-analytical variables on clinical laboratory tests. 3rd ed. Washington, DC:AACCP Press, 2007. 27
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THANKS FOR YOUR ATTENTION 29