LABORATORY ERRORS

SUMMARY: The majority of laboratory errors occur during the requesting and collection of specimens, and in the reporting and application of results. Frequency of patient misidentification can be considerably improved by replacing wristbands by patient barcode systems.  Inability to communicate critical results in timely fashion potentially compromises patient safety.

Of all laboratory errors, 4% are considered to have a major impact on patient care1. 

Practical Pointer

Medical decisions may have been erroneous because laboratory information was misleading

Results of laboratory tests have an intrinsic range of error.  That is to say, running the same test on the same specimen of body fluid will produce different results, though generally within a narrow, and clinically acceptable, range.  Accredited laboratories have built-in quality control routines for detecting unacceptable deviations from those ranges, and such measurement errors occur with a frequency of 0.5-1%

By contrast, laboratory errors before and after analysis can be common and frequently pose threats to patient safety. 

Examples of pre-analysis error rates are 1 in 4 for sampling blood levels before a drug dosage adjustment has taken full effect2 or selecting the wrong tests for diagnosis of hepatitis C2, and 6-7% for incorrectly identifying a hospitalised patient before taking a blood sample3. 

Examples of post-analysis latent errors with potentially serious consequences include rates of 7% for incorrect transmission of telephoned results2, 15% for failure to document critically high serum calcium levels in the clinical records3, 35% for not following procedures for identifying patients before transfusing blood and blood products4 and 5-6% for incompletely recording vital signs during blood transfusion4.  

Practical Pointer

Common laboratory errors of medicolegal significance:

  1. Misinterpretation because sample timing was incorrect
  2. Wrong tests requested
  3. Wrong patient
  4. Errors in telephoned urgent results
  5. Critically abnormal tests not documented

Patient Identification

Frequency of patient misidentification can be considerably improved by replacing wristbands by patient barcode systems. 

Incorrect or missing wristbands can result in delayed diagnosis, additional laboratory testing, treatment of the wrong patient for the wrong disease, and even death from a transfusion reaction. Missing bands were commonest, followed by missing identification information, illegible wristbands, incorrect identification information, and conflicting wristbands3.

Although most patient barcode systems are being used to reduce medication errors, preliminary research results include a 100% reduction in specimen collection errors and a 13% reduction in collection staff time2. More impressive yet, no labelling or transfusion errors occurred in more than 60000 transactions when both patients and blood were barcoded5 [].

Practical Pointer

Errors from incorrect or missing wristbands can be avoided by patient barcode systems

Critical Values

Inability to communicate critical results in timely fashion potentially compromises patient safety.  

Critical or panic values are laboratory results that are so far outside the normal range that they may require urgent action.  According to protocol, the laboratory must immediately report such a result to the responsible physician.  In 1 in 20 cases, that physician or his designate could not be found and the urgent reporting was abandoned6 []. 

Practical Pointer

Laboratories may not be able to reach the appropriate physician to report critically abnormal results

Copyright © 2009 Electronic Handbook of Legal Medicine