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How many mislabelled samples go unidentified? Results of a pilot study to determine the occult mislabelled sample rate
  1. Caitlin Raymond1,
  2. Liesel Dell’Osso1,
  3. David Guerra1,
  4. Julia Hernandez1,
  5. Leonel Rendon1,
  6. Donna Fuller1,
  7. Alejandro Villasante-Tezanos2,
  8. JuanDavid Garcia1,
  9. Peter McCaffrey1,
  10. Christopher Zahner1
  1. 1Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, Texas, USA
  2. 2Department of Biostatistics, The University of Texas Medical Branch at Galveston, Galveston, Texas, USA
  1. Correspondence to Dr Christopher Zahner, Department of Pathology, The University of Texas Medical Branch at Galveston, Galveston, TX 77555-0443, USA; cjzahner{at}


Background Specimens with incorrect patient information are both a critical safety error and difficult to identify. Estimates of sample mislabelling rely on subjective identification of mislabelling, with the possibility that not all mislabelled samples are being caught.

Methods We determined the blood type of two or more complete blood count specimens with the same patient label and assessed for discrepancies. We additionally determined the rate of identified sample mislabelling for the study period.

Results We found a rate of 3.17 per 1000 discrepancies over the study period. These discrepancies most likely represent occult, or unidentified, mislabelled samples. In contrast, the rate of identified sample mislabelling was 1.15 per 1000.

Conclusions This study suggests that specimens identified as, or known to be, mislabelled represent only a fraction of those mislabelled. These findings are currently being confirmed in our laboratory and are likely generalisable to other institutions.

  • quality assurance, health care
  • quality control
  • safety

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  • Handling editor Patrick J Twomey.

  • Contributors All authors on this study contributed to study design, data collection and preparation, or manuscript preparation.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.