Phases of Lab Testing and analyses:
1. Pre-analytical phase includes those processes that affect the laboratory results due to handling of the specimen sample prior to analysis.
2.The analytical phase includes those processes that occur during sample analysis or testing :
verification of instrument linearity,
verification of instrument precision,
verification of instrument accuracy,
verification of reagent lots,
through the use of quality control (QC) samples, procedures, and QC rules.
testing of Samples
3. Postanalytical processes include timely and accurate laboratory result reporting and other aspects that occur after the analysis phase.
Laboratory Variables:
A. Pre-analytical Variables:
I. Controlled variables II Uncontrolled variables
Patient preparation Age, gender, ethnicity, etc.
Specimen Collection
Test conducted
Separation & Aliquoting
Patient identification
Personnel
Turn around time
Laboratory Logs
Transcription Errors
Time of Collection
Posture
Prolonged Bed rest
Exercise
Circadian variation
Cortisol: Peak 6AM to 8AM
ACTH: Peak 6AM to 8AM
Growth hormone: Peak 10 PM
Catecholamines: 24hrs collection
Diet
Laboratory Errors
1.Pre-analytical Errors
Patient misidentification
Specimen mislabeled or unlabeled
Incorrect or compromised specimen
Insufficient Volume
Incorrect Vacuette
Spillage/ leakage
Inappropriate specimen transport conditions
Specimen processed incorrectly
Specimen stored inappropriately before testing
Wrong test(s) ordered
2.Analytical Errors
Analytical errors may be systematic or random
Instrument not calibrated
Instrument precision problem
QC not Done
Reagents not in room temp.
Reagent Expiry
Interfering substances present
Specimens mix – up
Sample Retention
3.Post-analytical Errors
Report not legible
Transcription error
Turn around time delayed
Incorrect interpretation
Sample Retention
Sample Retention
Whole blood, serum & plasma: - 48 hrs after report has been finalized.
Body fluids: - 48 hrs after report has been finalized
Urine – routine - 24 hrs after report has been finalized.
24hr Urines – samples discarded 48 hrs after report has been finalized.
