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Pre-analytical pitfalls: Missing and mislabeled specimens

Nam K Tran, PhD, HCLD (ABB), FAACC and Ying Liu, MD | February 26, 2020
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The Case

Case #1:

A 56-year-old man was admitted to the same-day surgery center for a planned biopsy procedure. Microbiological specimens were collected for culture and first transported to the central laboratory for processing at 1142. The samples were dropped off at the central laboratory receiving window where the time/date of receipt was recorded into a specimen tracking log and a temporary tracking barcode was issued at 1151.

At this institution, culture specimens are ultimately tested at the microbiology laboratory located 10 minutes away by courier (hourly pick up) at a satellite facility. Upon arrival at the satellite facility, samples are logged and accessioned for testing at their respective laboratory (e.g., microbiology). In this case, receipt of the culture specimen was confirmed by the central laboratory, however, the specimen never arrived at the microbiology laboratory. Both the central laboratory and satellite facility were not aware that the sample was missing until the ordering provider queried the laboratory about the result five days later. The ordering physician was notified of the missing sample. Unfortunately, the specimen was never found. Incident review did not identify any adverse events associated with the missing specimen. The patient did not manifest any signs or symptoms of infection one week and up to one month following the procedure.

Case #2:

A 59-year-old man was treated for a suspected myocardial infarction due to erroneous cardiac troponin results. The patient presented to the Emergency Department (ED) with chest pain, shortness of breath, and a history of chronic obstructive pulmonary disease. Initial cardiac troponin I concentrations were 4400 ng/L (99th percentile of the upper reference limit was 40 ng/L) with a B-type natriuretic peptide value of >5000 pg/mL. Aspirin, ticagrelor, and heparin were administered, and the patient was taken to the Cardiac Catheterization Lab. While undergoing catherization, it was revealed that the patient did not have any obstructed blood vessels. Chest, abdominal, and pelvis computerized tomography scans were also negative for pulmonary embolism and dissection. A repeat cardiac troponin I specimen was drawn, and the result was <10 ng/L. The Emergency Medicine physician contacted the Laboratory to determine the cause of such a large shift in results and the negative findings by the Cardiac Catherization Laboratory. As per routine procedure, the Clinical Laboratory immediately sequestered all samples related to the patient. Cardiac troponin I measurements were re-run and reported the same discrepancy. Blood typing of the two troponin specimens indicated they were not from the same patient. Follow-up investigation by the ED ultimately revealed the initial sample with the high cardiac troponin was from another patient presenting with septic shock and renal failure.

The Commentary

by Nam K Tran, PhD, HCLD (ABB), FAACC and Ying Liu, MD

It has been suggested that up to 70% of all medical decisions are based on some kind of pathology and/or laboratory result.1  Medical testing consists of three phases: (a) pre-analytical, (b) analytical, and (c) post-analytical 2-4 Up to 75% of all medical testing errors occur during the pre-analytical phase with the majority happening before any specimen arrives at laboratory.3,4 These include errors such as mislabeling of specimens, delayed transportation, collection into the wrong specimen container, inadequate specimen collection. In contrast, during the analytic phase, error rates are far lower. Modern laboratory testing incorporates numerous safeguards such as external and internal quality controls, highly regulated documentation of operator competency, and informatic tools – resulting in an analytic error rate of <13%. Examples of errors encountered during the analytic phase typically resides with improper instrument operation, faulty reagents, and sensor degradation. Sources of testing error occur during the post-analytic phase include transcription errors, delayed reporting of results, and applying incorrect correction factors (e.g., dilution correction).

Lost specimens between testing facilities is a type of pre-analytic error.2 In a typical hospital laboratory, tens of thousands of samples may be processed and tested each day. Some facilities may incorporate robotics (i.e., automation) to aid in the testing process to maximize speed while minimizing error, however, the transportation of specimens to and from the laboratory remains manual in nature. Larger facilities, such as the one described here, utilize internal or contracted courier services to transport samples from patient care facilities to multiple laboratories. Given that space is at a premium in many hospital facilities, clinical laboratories may de-centralize testing services across multiple buildings and placing high priority “STAT” tests in central laboratories located near emergency departments, operating rooms, and intensive care units, while slower or more esoteric tests may be based in more distant satellite facilities. Microbiology is a common specialty that may have facilities away from the main laboratory due to the historically slow nature of culture results – thus relying on couriers to retrieve samples from the patient care sites.5 For this patient case, the microbiology laboratory was located 10 minutes away from the initial receiving laboratory.

Mislabeled specimens are also a common pre-analytic error. Unfortunately, it is believed mislabeling errors are not always obvious and therefore under-reported.6-8 The busy nature of the ED environment increases the likelihood for mislabel events to happen and is further compounded when multiple healthcare personnel participate in patient care. Studies conducted by the College of American Pathologists (CAP) observed a rate of of 0.92/1,000 mislabel events across 120 institutions. Even more sobering, other CAP studies evaluating blood bank mislabels have reported error rates approaching 1.12%.6-8

For lost specimens, due to the nature of large, complex health systems, both medical care and laboratory facilities may be spread across a wide geographic area – creating a condition where samples exchange hands several times before arriving at their final destination. Large health networks may have multiple clinics strewn across a large geographical area and rely on couriers to transport specimens to the central laboratory. In some cases, samples may be sent to large referral laboratories in other states and require both ground and air couriers for transportation. Thus, specimens could be misplaced, accidentally discarded, or possibly intermixed with other specimen shipments at multiple points during this process. The frequency of lost samples reflects the challenges faced by hospital laboratories. A study by the University of Minnesota Medical Center (UMMC) laboratory found their facility could not account for about 6 to 7 specimens per week.9 This facility is relatively large and consists of 8 hospitals and 86 clinics. Review of contributing factors to UMMC’s operation found courier workspace, staffing, lack of interfaced specimen tracking systems including barcode and/or radio frequency identification (RFID) systems, and workflow to be potential areas for improvement. In another study, Steelman et al. described 684 adverse events and near misses involving surgical specimens.10 The data was derived from a database representing 50 health care facilities from 2011 to 2013. Common events included improper specimen labeling, collection/preservation, and transport. Of these 684 events, 8% resulted in either the need for additional treatment, or temporary or permanent harm to the patient. The most common causes of errors were hand-off communication problems, staff inattention, knowledge deficit, and environmental issues.

In Case #1, the root cause analysis identified several areas for improvement for this near-miss event including adoption of not only tracking logs, but staff sign-off of specimen shipment contents, and confirmation by the receiving satellite facility. This ensured central laboratory staff confirmed contents before departure, and the satellite facility confirming contents at time of receipt. Discordant shipment content lists are then immediately investigated, and the frequency of these events tracked

For mislabeled specimens, studies show the failure points occur at the time of collection where patients are misidentified, the use of handwritten labels at any point, mix-ups occurring before or after collection, mislabels at the laboratory during accessioning/aliquoting/centrifugation, or when relabeling specimens.6-8 Other contributing factors include the tendency to obtain “rainbow draws” (drawing tubes of every possible color to allow for additional testing at a later time). Such rainbow draws are controversial, and no data exists to support the benefit of this practice. In fact, it is more likely to waste blood and create perfect conditions for mislabeled specimens. In one study, the practice of collecting rainbow draws was attributed to 275 L of blood wasted per year.11  The root cause analysis from Case #2 revealed at least three nurses were managing the patient. The incorrect patient label was placed on the cardiac troponin I sample, which resulted in the report being attributed for the wrong patient. Outside of having an unnecessary invasive procedure, the patient in this case did not experience any other adverse events, but the outcome could certainly have been different.

Errors stemming from missing or mislabeled specimens are costly to institutions. In one study, the average cost due to a single irretrievable lost specimen was $548, and cumulative errors over a three-month period increased this value to $20,430.12 In contrast, a retrievable lost specimen incurred a cost of $401.25 per event, with a three-month cumulative value of $14,836. In Case #1, if the microbiology sample were to have been positive, resulting delays in the treatment of infection could be substantial. Studies have highlighted that every hour delay in treatment of severe infections, such as sepsis, exponentially increases the odds of death.13 Costs associated with iatrogenic injuries has been suggested to be about $3,961 and result in an increased length of stay of 0.77 days in the intensive care unit setting14 with pre-analytic error costs representing 0.23 to 1.2% of a total hospital operating cost15. For mislabeling errors, CAP estimates the cost to be about $712 per specimen. Based on CAP data, multiplying this cost with the number of mislabeled specimens, it is believed hospitals lose $280,000 per million specimens – amounting to equal or greater than $1 million for large high-volume hospitals.16 These costs are attributed to re-drawing specimens, as well as healthcare provider costs, and prolonging hospital lengths of stay.

In addition to increased financial costs to the healthcare system, the costs from missed, delayed, or wrong diagnoses due to lost or mislabeled specimens can be devastating or catastrophic to individual patients. For example, an incorrect labeled fine needle aspirate sample can lead to inappropriate treatment for the wrong patient.17 In one reported case, such an error resulted in the wrong patient receiving a pulmonary resection, and the other having delayed disease diagnosis. In another example, post-analytical reporting of results into the wrong patient electronic chart has caused patients to receive inappropriate treatment.17 In the end, the price for testing errors have both financial and human costs.  

Best practices implemented in these cases highlight the multifactorial nature addressing these common sources of medical error.9 A system of checks and balances can reduce errors, including organic elements such as laboratory personnel and electronic safeguards via barcode scanners, preventing the ordering of “rainbow draws,” personal barcode printers for nursing staff, reduce errors.9,18 Combining these measures with efficient workflows and workspace facilities provides means to further reduce the frequency of lost and mislabeled specimens in the laboratory. Future directions may include the use of advance informatic tools and RFID could significantly reduce the prevalence of lost specimens.9,19 Radio frequency identification has gained significant interest in laboratory medicine. Briefly, RFID systems rely on tags containing small radio transponders that can be used to track the movement of specimens over a defined space. These systems have been used in the commercial industry and has been adopted in the clinical laboratory for tracking reagent supply utilization.20  RFIDs were recommended in a study by Norgan et al. that found a 75% (6 vs. 24 events) decrease in lost specimens over a 6-month period after adopting this technology.19 However, adoption barriers do exist with the primary challenge being the cost of labeling each specimen with an RFID tag. Nonetheless, like with many technologies, the cost continues to decrease as seen with RFID adoption in laboratory reagent supplies and the retail industry.

Take-Home Points

  • The total testing process consists of the pre-analytic, analytic, and post-analytic phases. Medical testing error occurs most frequently during the pre-analytic phase.
  • Specimen loss is a common problem encountered by laboratories and the causes are generally multifactorial.
  • Mislabeled specimens occur frequently in healthcare and result in significant cost to the institution.
  • Some specimen loss or mislabeling events can lead to catastrophic outcomes such as consequential delays in cancer diagnoses, or unnecessary major surgical procedures.
  • Adoption of best practices such as specimen inventorying, elimination of “rainbow blood draws”, providing personal barcode printers to nursing staff can reduce error rates.
  • The use of RFID technology may further reduce specimen loss rates by as much as 75%.


Nam Tran, PhD
Associate Clinical Professor
Department of Pathology and Laboratory Medicine
UC Davis Health

Ying Liu, MD, PhD
Department of Pathology and Laboratory Medicine
UC Davis Health



We thank the UC Davis Department of Pathology and Laboratory Medicine Quality Team for their support in evaluating this case.


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This project was funded under contract number 75Q80119C00004 from the Agency for Healthcare Research and Quality (AHRQ), U.S. Department of Health and Human Services. The authors are solely responsible for this report’s contents, findings, and conclusions, which do not necessarily represent the views of AHRQ. Readers should not interpret any statement in this report as an official position of AHRQ or of the U.S. Department of Health and Human Services. None of the authors has any affiliation or financial involvement that conflicts with the material presented in this report. View AHRQ Disclaimers
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