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Quality Control in the Coagulation Laboratory Brisbane Australia Robyn Coleman.

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Presentation on theme: "Quality Control in the Coagulation Laboratory Brisbane Australia Robyn Coleman."— Presentation transcript:

1 Quality Control in the Coagulation Laboratory Brisbane Australia Robyn Coleman

2 What is quality control? An attempt to control and monitor a process to ensure a consistent outcome.

3 Why perform quality control in a medical laboratory ?  Because we need something to do before the samples arrive  The charts are pretty  Gives the QC officer a reason to come to work  Because the results we produce have a DIRECT effect on the lives of those patients who use our services

4 Patient Education Compliance Health Drug interactions Dosing Process DAWN DR experience INR Components for making warfarin therapy safe and effective.

5 Lab errors measuring PTT’s and INRs linked to bleeding, deaths at hospital. Reuters Health Information 2003  2003 Reuters Ltd. Errors in determining prothrombin time began when employees in the lab did not notice that they had been sent an old reagent, and used an incorrect ISI to calculate the INT. Dr Lurie said “they plugged the wrong number into their calculations” Due to the errors, the lab produced more than 2,000 INR readings that were falsely low. Patients tested during the time of the errors were more likely to experience bleeding complications. Three patient deaths were attributable to the mistake.

6 The Sample  Collection technique  Contamination by heparin or saline flushes  Ratio of blood to anticoagulant (9:1)  Low HCT causes change in final citrate concentration  Adequate mixing of sample without frothing  Transportation to testing facility - delay in testing  Clotted, haemolysed, icteric or lipaemic specimen  Incorrectly or unlabelled sample Sources of error in the coagulation lab.

7 Change in INR vs storage time Storage time (days) 40C Change in INR 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8

8 Reagent related problems  Selection of an appropriate reagent  Contaminated reagents  Reconstitution with incorrect volumes  Reconstitution with incorrect diluent  Defects in product due to mishandling in shipping and storage  Reagent used beyond stated stability or expiration date  Contaminated water used for reconstitution

9 Analytical Errors  Incorrect value assignment ( ISI, MNPT or std value)  Incorrect incubation or activation time  Incorrect or imprecise dispensing of reagents  Failure to use proper instrument operating procedures  Extrapolation beyond readable limits of reference curve  Failure to action instrument warning flags

10 Instrument Failure  Defective light source or detection system  Incorrect temperature  Poor reagent / sample delivery  Electrical Interferences  Reagent splash  Mechanical failure, e.g. reagent stirring etc

11 The most common source of error Human error !

12 Internal –  DailyVerify I, II, III for PT, INR, APTT, Fib  Should be run minimum daily or every 8 hours or every 40 samples or with new bottle of reagent  Patient samples should not be tested until QC accepted  If fails, retest by elimination until fault found External –  Monthly central review of Mean, SD of daily review  RCPA (and central review of) Quality control






18 RCPA Royal College of Pathologists Haematology QAP- Haemostasis  POC care – INR module  INR, APTT, Fibrinogen and D-Dimer  Special Haemostasis Thrombophilia von Willebrand testing





23 NATA  National Accreditation and Testing Authority  Primary function is Proficiency testing  Peer review of all technical processes  Licence to provide pathology services  Regular review every 3 years  Corporate surveillance

24 NATA Assessment  Relevant documentation( including its currency)  Appropriateness of methods and procedures  Suitability of equipment or instruments ( incl calibration )  Suitability of environment and supporting services  Adequacy of personnel ( number, training, skills etc)  Monitoring of processes / quality control measures  Handling and identification of test specimens or test items  Recording and reporting of results –documentation control

25 ISO9001/ IEC 17025  Traceability and accountability  Quality systems ( Documentation)  Non conformance  Complaints ( Internal and External)  Classification and review of NC ie Why did this error occur ? Random or system error  Corrective or preventative actions  Audits – allows regular review of all processes.  Horizontal  Vertical

26 So the aim for laboratory staff…  Produce consistent results,consistently  Pay attention to what is happening (eg new lot numbers)  Don’t assume it will be alright eventually.  Don’t assume it is someone else’s responsibility.  Trace ability and accountability.  Action faults efficiently and effectively.  Pro actively prevent faults by doing instrument maintenance


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