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Pre analytical in lab testing
- 1. Dr Normila AbdHadi Department of Pathology & Transfusion Hospital Kuala Krai
- 2. Table content • Medicalerrors and errors within laboratory total testing process • Impact of sample rejection • Pre analytical variables in laboratory total testing process • Common sample issues • Ways to minimize pre-analytical errors • Conclusion
- 3. Medical Errors • Thecomplexity of the current healthcare environment has increased the potential of medical errors. • Statistics by the Institute of Medicine (IOM):- – Hospital-based errors is 8th leading cause of death in US – Medical errors contribute to >1 million injuries and approximately 44k - 98k deaths in hospital annually – These errors results in 2.4 milion extra days of hospitalization thus increase hospital costs. • A study of medical errors published in the New England Journal of Medicine: – 11% of patients recieved potential harmful care – 46% of patients did not recieved the recommended care
- 4. Laboratory service &testing • Laboratory services are the backbone of the modern healthcare sector. • Laboratory testing provides essential information used by physicians. • An estimated 60-70% of medical decisions are based on laboratory test results. (Regan M & Forsman R, 2006) • Lab tests are increasingly important position in – the diagnostic process – in monitoring the effect of therapy – in monitoring health of the individual
- 5. Laboratory Total TestingProcess Total testing process starts and end with patient Laboratory Total Testing Process A series of activities, starting with the clinical question in the clinician's mind, leading to test selection, sample collection, transport to the laboratory, analysis, reporting back to the clinician, and final interpretation and decision making by the clinician
- 6. Laboratory Total TestingProcessLaboratory Total Testing Process
- 7. Laboratory Errors Hammerling J.A,2011 “any defect from ordering of tests to reporting of results and appropriately interpreting and reacting on this”’ (Hawkins R., 2012)
- 8. Review of laberrors by processing phase Reference Preanalytical % Analytical % Postanalytical % Goldschmidt and Lent 53.0 23.0 24.0 Nutting et al. 55.6 13.3 30.0 Plebani and Carraro 68.2 13.3 18.5 Stahl et al. 75.0 16.0 9.0
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- 11. Impacts of rejection •Patients – Delayed diagnosis and treatment – Misdiagnosed and inappropriate treatment – Increased risks to patients safety – Discomfort and stress imposed on patient – Prolonged hospital stay and increase cost of health care Sol F. Green “The cost of poor blood specimen quality and errors in preanalytical processes” Clinical Biochemistry 2013 Liyun Cao Et Al. “Causes and Impact of specimen rejection in a clinical chemistry laboratory” Clinica Chimica Acta 2016
- 12. Medical outcome asa result of laboratory errors Sol Green “Improving the preanalytical process: The focus on specimen quality” Data management and Biostatictics Journal 2008
- 13. Impacts of rejection •Laboratory – Prolonged turn around time – Extra work – communicate between clinicians and lab personal – Extra expenditure/cost for recollection and retesting and reanalysis. • re-venipuncture • Cost – syringe, tube, form • Reagent use Sol F. Green “The cost of poor blood specimen quality and errors in preanalytical processes” Clinical Biochemistry 2013 Liyun Cao Et Al. “Causes and Impact of specimen rejection in a clinical chemistry laboratory” Clinica Chimica Acta 2016
- 14. The pre-analytical phase •The most error-prone part of laboratory testing due to its complexity • due to presence of many steps that occur outside as well as inside the laboratory • most of the errors occur outside the lab
- 17. Source of PREANALYTICAL variation in laboratory analysis • Physiological/biological factor – Beyond control of phlebotomist/lab staff • Technical/pre-analytical factor – Within control of phlebotomist/lab worker
- 18. Physiological and biologicalfactors Beyond control Age Race Gender Pregnancy Diet Exercise Environme nt/ lifesyle
- 19. Technical/pre analytical factors •Within control of phlebotomist/lab staff • These may be divided into two broad categories Category Variables Sample collection Pt identification and sampling Phlebotomy technique Sample volume Collection tube Sample handling Storage Agitation, centrifugation Transport conditions Delays in transport to the lab for processing
- 20. Root causes ofPre-analytical variables • The most frequently encountered causes of pre-analytical errors are: • hemolysis • incorrect patient identification • insufficient sample volume, and • clotted specimens (Salvago et. al J Eval Clin Pract 2008)
- 21. Sample collection -Incorrect patient identification • Most important steps in venipuncture procedure. • Incorrect patient identification prior to sample collection – is one of the major & most dangerous source of pre-analytical error. • This can result in • may be fatal if an acute haemolytic transfusion reaction occured. • delayed diagnosis • additional lab testing • treatment of a patient for the wrong medical condition
- 22. ...Incorrect patient identification Outpatients: to be asked of full name. This is verified with the information on the request form Inpatients : check identification band to verify name and hospital identification number match to the order Young or mentally incompetent patient : need to ask patient’s parent, relative or nurses in-charge to identify him/her
- 23. • Best practice: –Draw and label the specimen at the bedside – Do not label tube prior to venipuncture – The outpatient must not be dismissed before labelling is complete – Make sure the information on the request form and sample are tally ...Incorrect patient identification
- 24. • Actual timeof collection – The concentration of many analytes fluctuates over 24 hours – These includes cortisol, hemoglobin, potassium, sodium, renin and aldosterone Test Subjected to diurnal variation Acid phosphatases* ACTH Cortisol (& other adrenal steroid) Growth hormone Insulin Parathyroid hormone Renin/aldosterone TSH* Testosterone* *higher in afternoon and evening All others higher in the morning Test affected by meals LDH Phosphate* Potassium* Sodium TG Urine pH Glucose Growth hormone Insulin Ionized calcium *lowest after meal; all others higher Sample collection – Sampling time
- 25. • Best sitesfor venipuncture are superficial veins of the upper limb • Median cubital vein • Cephalic vein • Basilic vein Sample collection – Sampling site
- 26. • Inappropriate siteinclude • Arm on side of mastectomy • Oedematous areas • Hematomas • Damaged veins (eg. Thromboses, non-elastic veins) • Scarred areas • Arms with fistulas or vascular grafts • Site above IV cannula** – Common prob: NaCl drip ↑ Na & Cl (other analytes ±↓) …Sampling site
- 27. 1. Tourniquet applications –Aim for max application time of 1 minute • to avoid localised stasis with haemoconcentration increased Alb, T.protein & protein-bound analytes ( e.g Calcium, Tbili, Chol, iron) 2. Inappropriately narrow gauge needle leading to clotting & haemolysis of sample 3. Allow alcohol to dry before sample collection leading to haemolysis Sample collection – Phlebotomy technique
- 28. …Phlebotomy technique 4. Orderof draw – To avoid contamination of anticoagulant erroneous results – Follow specific recommended ‘order of draw’ Blood culture tube ↓ Coagulation tube(light blue) ↓ Serum tube ↓ ↓ Heparin tube ↓ EDTA ↓ Glycolytic inhibitor- glucose
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- 30. …Phlebotomy technique 5. Appropriatevolume – Appropriate blood to additive ratio needs to be maintained by allowing tubes to fill with blood until the flow stops (vacuum exhausted)
- 31. Correct volume ofblood drawn • Crucial in ensure sufficient sample for analysis • Also to avoid under filling or over filling volume impact • Insufficient sample is one of commonest cause for rejected sample
- 32. Fill volume impact Underfilling Over filling • Can lead to excessive concentration of heparin • Can interfere with some tests results (eg. Reduced values for ionised calcium & Magnesium) • In gel tube, under filling will increase gel-to-specimen area ratio, which increase adsorption of some analytes to gel • Dilution of additive • Inadequate anticoagulation, leading to formation of micro clots in plasma which can affect instrument performance
- 33. 6. Mixing oftubes – Inappropriate mixing may cause clotting and cannot processed for FBC testing – Clotting may produce false leucopenia, low RBC count & hematocrit – Micro-clots interfere with instrument performance • Leading to downtime delay processing and test reporting …Phlebotomy technique
- 35. • Delays of>6 hours between collection and processing of INR or PT samples can cause significant changes in results (i.e >10%) • Delayed transportation to the lab affects some test result – E.g: K, AST, ALT etc • Improper preservation – e.g ice or not ACTH, ammonia, lactate etc Sample handling
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- 37. Haemolysis of sample •Haemolysis - breakage of the RBC’s membrane, causing release of Hb and other internal components into the surrounding fluid • Test affected: K, LDH, AST, bHCG, CK, coagulation test, iron, digoxin • Degree of haemolysis….
- 39. Haemolysis of sample •Haemolysis can occur from two sources – In-vivo haemolysis • Due to pathological conditions such as AIHA or transfusion reaction – In-vitro haemolysis • Can occur due to improper sample collection, processing or transport
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- 41. Hemolysis - duringspecimen processing, handling and transportation
- 42. Reducing the causeof pre-analytical error • Quality control • Identify and monitor possible causes of pre-analytical errors • QA Programs should include monitoring the sample collection process • Good practice • Understand the current practice vs hospital procedures and best practice • Training and education programs • Support staff by providing clear and effective training • Tracking the cost of poor quality and errors in preanalytical procsses: proven steps labs can use to boost patient outcomes, a lecture by Sol F. Green, BD Preanalytical Systems
- 43. Ways to minimizepre-analytical errors • Comprehensive and standardized training programs reaching a wide range of staffs – HO, SN, MO on: – SOP – Specific competency assessment – Academic seminars to inform impacts of pre-analytical errors on patient diagnoses and and therapy Sol F. Green “The cost of poor blood specimen quality and errors in preanalytical processes” Clinical Biochemistry 2013 Liyun Cao Et Al. “Causes and Impact of specimen rejection in a clinical chemistry laboratory” Clinica Chimica Acta 2016
- 44. Conclusion • Health providerrelies on laboratory test results for management of the patients. • The lab responsible to provide accurate and reliable test results. • The accuracy of test results depend greatly on the quality of the specimens sent to the lab
- 45. Take home message •Fill up request form completely – INCLUDING DATE & TIME of collection • Make sure correct sample for correct pt • Make sure correct tube container • Make sure appropriate sample volume • Practice correct order of draw to avoid contamination • Any doubt, call lab for enquiry
- 48. References • Regan M,Forsman R. The impact of the laboratory on disease management, Dis Manag. 2006 Apr;9(2):122-30. • Robert Hawkins, M.D., Managing the Pre- and Post-analytical Phases of the Total Testing Process, Ann Lab Med 2012;32:5-16. • Hammerling J. A., A Review of Medical Errors in Laboratory Diagnostic and Where We Are Today, LABMEDICINE; Vol. 43, No. 2; 2012 • Sintayehu A. et al., Errors in the Total testing Process in the Clinical Chemistry Laboratory at the University of Gondar Hospital, Euthopia J Health Sci; Vol. 28, No. 2; 2018
Editor's Notes
- #5 Healthcare providers depend on accurate and precise lab results in order to do their jobs well and give patients the best possible care.
- #7 Laboratory TTP is subjected to many variables as it can occur in all the phases of lab. testing pre-ana: al steps fr time of test ordering unti; sample ready for analysis ana: actual specimen analysis post-ana: test reporting and interpretation
- #45 MASUKKAN JOURNAL