A report in the news earlier this year (Moore 2018) rekindled our interest in the issue of specimen mixups. A patient underwent a prostatectomy on the basis of a biopsy that showed an invasive, aggressive cancer. But it turned out that the removed prostate was healthy. The biopsy results that showed the cancer belonged to another patient. There had been a mixup. And this had occurred despite the fact that the patient, at the urologist’s suggestion, had a DNA swab taken at the same time he had the biopsy. That should have made it nearly impossible to mix up test results among patients. But that’s exactly what happened.
We’ve done several columns on lost surgical specimens or misidentification of surgical samples. In our March 24, 2015 Patient Safety Tip of the Week “Specimen Issues in Prostate Cancer” some of the estimates of switched or contaminated prostate biopsy specimens ranged from 1% to 2.5%. But those were largely estimates. A more realistic estimate comes from a recent clinical trial, the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) prostate cancer risk reduction study. After three cases of biopsy sample misidentification were discovered in the first 2 years of that study, all protocol-mandated biopsy samples were DNA tested to verify biopsy identity (Marberger 2011). A total of 11,235 primary study biopsy samples were DNA identity tested. The results found that 27 biopsies were confirmed to be mismatched to the patient for whom they were originally submitted. In the first two years of the study, 0.4% of biopsies (n = 26) were found to be mismatched. After a rigorous improvement process, only a single biopsy was mismatched in the following two years.
The authors suggest some key strategies to address biopsy identification errors in clinical trials but several of them are pertinent to any setting:
We’ve talked about doing DNA identity testing in several of our prior columns listed below and noted that there are some pathologists and urologists who have suggested such should be routine for all patients undergoing prostate biopsy. Note that a proposed bill, the Prostate Cancer Misdiagnosis Elimination Act of 2017, calls for Medicare to reimburse labs $200 for DNA testing that compares and matches the patient's biopsy tissue with cells from the inside the cheek that are taken with a cotton swab to ensure both came from the same person (Mulcahy 2017). To our knowledge that bill has not yet progressed through Congress.
An analysis of closed pathology claims (Akland 2018) is very revealing. The majority of the claims were related to misreads, but in 38% of the claims there were systems issues that contributed. As we’ve seen with most “lab” errors, the majority occur in the pre-analytic phase. Specimen loss/mix-ups accounted for 78% of the systems issues. The other 22% involved specimen contamination (eg. floaters, carry-over artifacts and cross-contamination).
Errors may occur related to the handling practices of the submitting physician by his/her staff, But they may also occur within the lab related to transport and receiving the specimen, or related to accessioning and slide identification. Examples of errors include mislabeling, misidentification, sorting, routing and pour-off (decanting) errors.
Carolyn Akland provides several illustrative case descriptions and then offers the following excellent recommendations pertinent to labeling and identification issues:
We strongly encourage you to read Akland’s analysis since she also has excellent recommendations regarding communication issues, using all available clinical information when rendering interpretations, avoiding interruptions and distractions, how to deal with and communicate amended reports, and others.
Lippi and colleagues (Lippi 2017a) recently published an article on patient and sample identification in the lab. They identified the following causes of identification errors in medical laboratory:
• Incorrect patient registration
• Reliance on wrong patient data
• Error in order entry (incorrect or incomplete data entry)
• Order mistranscription
• Collection of biological specimens from the wrong patient
• Inappropriate labeling of specimens
• Specimens mislabeled
• Specimens partially labeled
• Specimens unlabeled
• Illegible label
• Inaccurate entry or transmission of test results in the Laboratory Information System
Homonymy, of course, refers to names sounding alike. They note that in one hospital district in Texas, 2488 patients were named Maria Garcia, and 231 of these (9.3%) also shared the same date of birth (Lippi 2017a)!
They note that Joint Commission’s National Patient Safety Goal NPSG.01.01.01 mandates that at least two patient identifiers should be used when collecting blood samples and other specimens for clinical testing, or when providing other treatments and procedures. Notably, the room number or physical location of the patient should not be used as identifiers, whereas containers used for blood and other specimens should be labeled in the presence of the patient.
Lippi et al. point out an important distinction between handling of blood samples compared to surgical specimens. Whereas we’ve emphasized you should not pre-label containers for biopsies or surgical specimens, they recommend the practice for blood samples should be pre-labelling of tubes. There apparently have been discrepancies in the recommendations amongst the several specialty organizations covering laboratories, but evidence apparently suggests that post-collection labeling of tubes carries a higher risk of identification errors (Lippi 2011).
Lippi et al. (Lippi 2017a) note that conventional or two-dimensional (2D) barcoded wristbands are indeed the most used approach for patient identification around the globe. But they go on to discuss the roles of technological solutions to the identification process, radio-frequency identification (RFID) tags, infrared (IR)-based patient tracking, wireless networks, patient smart cards and biometric technologies, each of which has its own advantages and limitations. They also talk about future developments, including an automated device based on four cameras which photographs the outside of a sample tube and then recognizes discrepancies between patient identity in the lab information system versus that on the blood tube label by means of optical character recognition (OCR). Another is a recently developed chip-size passive RFID tag also offers a locating capability and read range that are comparable to an active tag, but in a form factor and price that would allow to attach the tags to disposable labels.
In yet another paper by Lippi and colleagues (Lippi 2017b) note that the frequency of misidentification in vitro laboratory diagnostic testing may be relatively low compared to that of other laboratory errors (i.e., usually comprised between 0.01 and 0.1% of all specimens received). But up to 10–20% of these errors translate into harm for patients and may impact other human and economic resources.
They state the healthcare system should be re-engineered to act proactively to address this important problem. The advocate the widespread use of more than two unique patient identifiers, the accurate education and training of healthcare personnel, the delivery of more resources for patient safety (i.e., implementation of safer technological tools), and the use of customized solutions according to local organization and resources and, as above, after weighing advantages and drawbacks, labeling blood collection tubes before and not after venipuncture as a safer practice for safeguarding patient safety and optimizing phlebotomist's activity.
Some of our other columns on errors related to laboratory studies:
Moore D. His doctor said it was cancer. It was not. But the lab mix-up news came too late. St. Louis Post-Dispatch 2018; February 11, 2018
Akland C. An Analysis of Pathology Closed Claims, SVMIC (State Volunteer Mutual Insurance Company) January, 2017
Marberger M, McConnell JD, Fowler I, et al. Biopsy Misidentification Identified by DNA Profiling in a Large Multicenter Trial. J Clin Oncol 2011; 29(13): 1744-1749
Mulcahy N. A Bill to 'Eliminate Prostate Cancer Misdiagnosis'. Medscape Medical News 2017; November 17, 2017
Lippi G, Chiozza L, Mattiuzzi C, Plebani M. Patient and Sample Identification. Out of the Maze? J Med Biochem 2017; 36(2): 107-112
Lippi G, Sonntag O, Plebani M. Appropriate labelling of blood collection tubes: a step ahead towards patient's safety. Clin Chem Lab Med 2011; 49: 192-1923
Lippi G, Mattiuzzi C, Bovo C, Favaloro EJ. Managing the patient identification crisis in healthcare and laboratory medicine. Clinical Biochemistry 2017; 50(10-11): 562-567