laboratory errors in medical practice
TRANSCRIPT
Laboratory Errors in Medical PracticeMohammad Tanvir IslamAssistant Professor , MedicineBangabandhu Sheikh Mujib Medical University
“Anyone who has never made a mistake has never tried anything new.”
“Smart people learn from their mistakes.
But the real sharp ones learn from the mistakes of others.”
Brandon Mull
Why did the TITANIC sink?
Laboratory Testing CyclePre-Analytic
phaseOrdering a test
Order transferred to lab
Identifying information entered
Specimen obtained
Analytic phase
Specimen analyzed
Post analytic phaseReport generated
Result conveyed to clinician
Data interpretedClinical response to
result
• 0.10- 3.0%• Mostly pre-analytic and post-analytic• Analytic mistakes are <10% of all errors
Pre-Analytic
• Inappropriate test request 46%-68.2%• Order entry errors• Misidentification of patient• Container inappropriate• Sample collection and transport inadequate• Inadequate sample/anticoagulant volume ratio• Insufficient sample volume• Sorting and routing errors• Labeling errors
Questions to ask Before ordering a Test
• Why is the test being ordered• What are the consequences of not
ordering the test• How good is the test in discriminating
between Health versus Disease• How are the test results interpreted• How test results influence Mx & outcome
Clinical Performance Characteristics
• Prevalence• Sensitivity• Specificity• Efficiency• Positive Predictive Value• Negative Predictive Value
• In useful test sensitivity+specificity should be>170• Prevalence of a disease can affect the PPV /NPV• Cutoff value of a test can change the sensitivity &
specificity
Shotgun versus Rifle
Common Causes of Pre-analytical Error
Biological• Age• Sex • Race (Blacks vs. Caucasians)
Timing of test Behavioral• Diet• Obesity• Smoking• Alcohol intake• Caffeine intake• Exercise• Stress
Diseases: • Hypothyroidism • Nephrotic syndrome/chronic renal
failure • Biliary tract obstruction
Drug Therapy: • Amiodaron – on thyroid profile• Diuretics –on pleural fluid• Propanolol • Oral contraceptives• Prednisolone-on immune markers
Timing of test
• Hepatitis virus • Dengue serology• Cardiac enzymes• Pencreatic enzymes• Widal test
• Pregnancy• Specimen Collection & Handling
– Specimen obtained from wrong patient*– Specimen mix-up*– Nonfasting vs. fasting (12 h)
• Anticoagulant: – EDTA – Heparin
• Capillary vs. venous blood• Hemoconcentration (eg, use of a tourniquet)• Specimen storage (@ 0–4 °C for up to 4 days)
Non-specific laboratory abnormalities in thyroid dysfunction
Thyrotoxicosis
Serum enzymes – Raised alanine aminotransferase, γ-glutamyl transferase (GGT), and alkaline
phosphatase from liver and bone
• Raised bilirubin • Mild hypercalcaemia • Glycosuria
– Associated diabetes mellitus – 'Lag storage' glycosuria
Hypothyroidism
Serum enzymes – Raised creatine kinase, aspartate aminotransferase, lactate dehydrogenase (LDH)
• Hypercholesterolaemia • Anaemia
– Normochromic normocytic or macrocytic
• Hyponatraemia
Analytic
• Equipment malfunction 7%-13%• Sample mix-ups/interference• Undetected failure in quality control• Procedure not followed• Can be RANDOM or SYSTEMIC
Post-Analytic
• Failure in reporting 18.5%-47%• Erroneous validation of analytical data• Improper data entry
•This was Captain E. J. Smith's retirement trip. All he had to do was get to New York in record time•Captain Smith ignored seven iceberg warnings from his crew and other ships •If he had called for the ship to slow down then maybe the Titanic disaster would not have happened
• About three million rivets were used to hold the sections of the Titanic together• They were made of sub-standard iron
Bruice Ismay
• Wanted to show that they could make a six-day crossing• To meet this schedule the Titanic could not afford to slow down• It is believed that Ismay put pressure on Captain Smith to maintain the speed of the ship
1. Titanic had sixteen watertight compartments. 2. Compartments did not reach as high as they should have done. 3. The White Star Line did not want them to go all the way up because this would have reduced living space in first class. 4. If Mr Andrews, the ship's architect, had insisted on making them the correct height then maybe the Titanic would not have sunk.
The final iceberg warning sent to Titanic was from the Californian.
Captained by Stanley Lord, she had stopped for the night about 19 miles north of Titanic. At around 11.15, Californian's radio operator turned off the radio and went to bed.
• “Good judgment comes from experience, and experience comes from bad judgment.” ― Rita Mae Brown
THANK YOU