Errors encountered in the diagnostic pathway: A prospective single‐institution study

Biopsy specimens go through a diagnostic pathway before a pathology report is rendered for the clinician. Errors can occur at any step in this pathway.


| INTRODUCTION
Biopsy is an integral tool in the dermatologist's armamentarium for disease diagnosis. As a specimen goes from the clinic to the dermatopathology lab, multiple transfers and hand-offs in communication occur. A specimen may travel from the clinical provider to the medical assistant, the courier, and the histotechnician before arriving at the dermatopathologist's microscope. After the dermatopathologist renders a diagnosis, the data must be entered and the report delivered to the clinician. An error can occur at any step in the diagnostic pathway, potentially resulting in delayed or incorrect patient management.
Formal definitions and guidelines to assess laboratory errors have been described to improve patient safety. 1 However, most of what is known involves anatomic pathology and laboratory medicine. There is a paucity of literature on errors encountered in dermatopathology.
Previous studies investigating dermatopathology errors have focused on specific aspects of the diagnostic pathway, such as amendment rates, data entry errors, or missing pathology specimens. [2][3][4] The impact of medical errors is profound, costing the healthcare system an estimated $4-$20 billion annually, and is a leading cause of death in the United States. [5][6][7] A study of malpractice claims in pathology shows that while pathology claim frequency is low, the claim severity is high, especially in melanoma misdiagnoses. 8 While the overall error rates for pathology are reportedly low, their impact can be significant. Considering these findings, we conducted a prospective 1-year study to analyze where errors occurred along the diagnostic pathway at a single academic dermatopathology laboratory, with the fundamental objective to reduce errors and improve dermatopathology services.

| MATERIALS AND METHODS
A 1-year prospective study was conducted at a single academic institution to identify and characterize errors that occurred in the diagnostic pathway from the clinic to the dermatopathology laboratory. The study investigated all specimens received by the dermatopathology laboratory from July 1, 2021 to June 30, 2022. The study received exempt status from the Thomas Jefferson University Institutional Review Board.
The dermatopathology lab comprised one dermatopathologist, one dermatopathology fellow, and two histotechnicians. Fifty-eight providers from twenty-two different academic institutions and outpatient clinics sent in biopsy specimens for interpretation and consultation. Academic institutions and outpatient clinics accounted for 31% and 69% of specimens received, respectively. The Beaker module of the EpicCare electronic medical record served as the laboratory information system. Manual and automatic faxing systems along with electronic interfacing delivered final pathology reports back to the clinician.
Errors were categorized by incident type, source of error, stage of occurrence, who caught the error, and type of error. The incident type included incorrect submitter/provider, misspelling of site or diagnosis, incorrect test ordered, incorrect clinical information, the transmission of reports, diagnostic error, incorrect patient information, specimen mix-up, incorrect entry of correct diagnosis, and wrong site. The source of error included the clinic, dermatopathologist, histotechnician, and technology. The person who identified the error included the clinician, dermatopathologist, histotechnician, and administrative staff. The stage of error occurrence was categorized as pre-analytical (requisition form inaccuracies, tissue sectioning, etc.), analytical (diagnostic misinterpretations), and post-analytical (faxing reports, data entry, etc.).
The type of error was categorized into slips, lapses, mistakes, and nonhuman errors based on formal definitions used in the medical literature. 9,10 Slips and lapses (errors of execution) occur with correct intention but have an incorrect outcome. Slips involve errors secondary to inattention and lapses involve errors secondary to omission, such as forgetting to do something. 9 Mistakes (errors of planning) occur when an individual correctly performs the wrong action believing they have performed the right action. 9 Overlap expectedly exists when trying to classify the human error into these categories. Technological issues accounted for nonhuman errors.
Diagnostic errors were defined as errors in specimen interpretation by the dermatopathologist. These were categorized into major and minor misinterpretations dependent on if they would change medical management. Misdiagnoses secondary to sampling error or inadequate specimens were omitted.

| RESULTS
A total of 25 662 specimens were processed during the study period, and 190 errors were recorded (an error rate of 0.7%). There were 126 amendments made to the final pathology report to correct errors.  Figure 4 illustrates who initially discovered the errors. Most often, the clinician identified the mistake in 48.9% of cases (n = 93), followed by the dermatopathologist in 13.7% of cases (n = 26), and the histotechnician in 3.7% of cases (n = 7). In 30.5% of cases (n = 58), it was unknown who identified the error. In these cases, the data was incompletely recorded. Figure 5 categorizes errors into slips (n = 156, 82.1% of cases), lapses (n = 14, 7.4% of cases), mistakes (n = 9, 4.7% of cases), and nonhuman errors (n = 11, 5.8% of cases).
Diagnostic errors accounted for 17 out of 190 errors (8.9%) (see Table 1). Nine of 17 diagnostic errors were considered major diagnostic misinterpretations. Four cases involved melanocytic lesions, two cases involved non-melanocytic neoplasms, and three cases involved inflammatory dermatoses.

| DISCUSSION
Most of the literature on laboratory errors involves anatomic pathology and laboratory medicine. Little is known about errors in dermatopathology outside of narrow topics. Our study serves to wholly examine the diagnostic pathway, from the initial specimen collection to the final pathology report (see Figure 2).
In our study, 190 errors were recorded for 25 662 specimens, resulting in an error rate of 0.7%. A similar study in anatomic pathology identified 132 errors from 19 774 specimens, resulting in a comparable error rate of 0.7%. 11 However, the study only investigated errors occurring in histologic preparation, therefore underestimating the total error rate. A multi-institutional study of report amendments F I G U R E 1 Errors by incident type. Examples of errors for: (A) wrong site-that is, incorrect laterality or body site; (B) incorrect entry of a correct diagnosis-that is, forgetting to include a stain or additional study in the report; (C) specimen mix-up-that is, switching specimens A and B within a patient; (D) incorrect patient information-that is, wrong birth date entered for a patient; (E) diagnostic error-that is, missing fungal hyphae in a biopsy specimen; (F) transmission of reports-that is, fax machine only transmitted half the report; (G) incorrect clinical informationthat is, clinical differential diagnosis not written on the pathology report; (H) incorrect test ordered-that is, incorrect immunohistochemical stain ordered; (I) misspelling of site or diagnosis-that is, spelling mistakes on the pathology report; (J) incorrect submitter/provider-that is, wrong provider listed on the requisition form.
F I G U R E 2 Errors by stage of occurrence. The pre-analytical phase included all instances of specimen handling before the dermatopathologist viewed the slide (n = 128, 67.4% of cases). The analytical phase included diagnostic errors at the microscope (n = 17, 8.9% of cases). The postanalytical phase involved errors with the production of a diagnostic pathology report (n = 45, 23.7% of cases).

F I G U R E 3 Errors by source.
Errors occurred as a result of the clinical staff when labeling and packaging biopsies, with the histotechnicians during tissue processing, and the dermatopathologist and dermatopathology fellow during diagnosis and data entry. Technology errors included issues with faxing and interfacing pathology reports back to the clinician.
found an annual amendment rate of 4.8/1000 surgical pathology cases. 12 A similar study at a single institution's dermatopathology laboratory documented an amendment rate of 1.1% over 1.5 years. We recorded 126 amendments during the 1-year study period for a comparable amendment rate of 4.9/1000 dermatopathology cases. The literature provides supporting evidence that overall, errors rarely occurred in the diagnostic pathway and happen at rates comparable to what we report here for dermatopathology.
To correctly apply a study of laboratory errors, definitions and taxonomy must be correctly outlined. 1  The predominance of pre-analytical errors parallels the common incident types (see Figure 1). The most frequent errors were an incorrect biopsy site (34.2% of cases), incorrect data entry of a correct diagnosis (13.2% of cases), and a specimen mix-up (12.1% of cases).

Both incorrect biopsy site and specimen mix-up errors occurred
almost exclusively in the pre-analytical phase. An incorrect biopsy site error included incidents when a specimen was labeled with the wrong laterality (i.e., right arm vs. left arm) or the wrong site (i.e., arm vs. leg). These errors, comprising over a third of the total errors, occurred mostly at the clinic level, highlighting an area for quality improvement.
Depending on institutional and clinical practices, multiple people are often involved in the labeling and identification of specimens, including ancillary staff, resident physicians, mid-level providers, and attending physicians. As an example, in our academic institution's clinic, resident physicians communicate verbally and through notations in the electronic medical record system to medical assistants who enter the information, print off the requisition form, and package the specimen for delivery to the laboratory. Outpatient clinics that also send specimens to vary slightly in their specimen collection pathways.
F I G U R E 4 Person who identified the error. This was the individual who initially reported the error so that it could be recorded and addressed.
F I G U R E 5 Errors by type of error. Human error can be classified into mistakes and execution errors. Execution errors include slips and lapses. Slips occur due to inattention, and lapses occur due to omission.
Potential errors occur at every junction, including with the provider and in the communication hand-off to ancillary staff.
Specimen mix-ups occurred primarily in the pre-analytical phase at the specimen collection or tissue processing stages. These included transposed sites, switching specimen labels within the same patient, switching labels between different patients, and empty bottle specimens. Like biopsy site errors, specimen mix-ups can reflect workflow flaws in the clinic or tissue grossing laboratory. Of note, we reported six incidents of empty bottle specimens out of 25 662 total specimens. One study reported a comparable 83 empty bottle specimens from 270 754 specimens at a single academic dermatopathology laboratory. 2 Empty bottle specimens happen rarely but can lead to significant patient inconvenience and delays in care.
Importantly, 17 diagnostic errors occurred in the 1-year study period, with 9 representing major diagnostic misinterpretations. The breadth of these cases included four melanocytic neoplasms, two non-melanocytic neoplasms, and three inflammatory dermatoses (see Table 1). Figure 6 highlights an example of a major diagnostic misinterpretation of an inflammatory dermatosis. In one review of dermatopathology report amendments, the authors reported 35 diagnostic misinterpretations out of 86 amended reports, with 24 cases representing major diagnostic changes. 4 These studies, including ours, intrinsically underestimate the number of diagnostic errors. Many minor errors go unnoticed and unreported due to negligible patient impact, such as missing a melanocytic nevus within the architecture of a fibroepithelial polyp. Clinicians may neglect to provide feedback to dermatopathologists in challenging cases that require extensive clinicopathologic correlation. Our study shows that dermatopathologists heavily rely on clinician feedback in identifying errors, with clinicians detecting the error in 48.9% of cases compared to the dermatopathologist in only 13.7% of cases (see Figure 4). Without clinician feedback, dermatopathologists would be unaware of most laboratory errors and misdiagnoses.
Human errors can be broadly categorized into slips, lapses, and mistakes. 9 From a medicolegal perspective on errors, a failure to diagnose ranks as a top reason for physician lawsuits.15 A failure to diagnose can result from the failure of a planned action to be completed as intended (slip and lapse, i.e., inattention leading to overlooking hyphae in the cornified layer) or the use of a wrong plan to achieve an aim (a mistake, i.e., misinterpreting hyphae of dermatophytosis for T A B L E 1 Major and minor diagnostic errors. pityriasis versicolor). The Institute of Medicine used the terms, slips, lapses, and mistakes to define medical errors in its national healthcare quality report, and their usage has been commonly adopted in studies on pathology errors as well. 11,[16][17][18][19] In our study, slips dominated the type of errors (82.1% of cases), followed by lapses (7.4% of cases), and mistakes (4.8% of cases) (see Figure 5) These incidents can reflect systemic issues with the transference of information from provider to ancillary staff, inconsistent preprocedure timeouts, external disturbances, or a lack of stops and checks in procedural pathways. Creating a standard biopsy protocol for all providers and ancillary staff to learn can help minimize these errors.
For example, a biopsy protocol can include standardized guidelines for specimen labeling, starting from superior to inferior and left to right (i.e., the most superior specimen site is always labeled A). However, while system changes can reduce faults, human errors cannot be fully eliminated. Most errors were classified as slips, a type of execution error that occurs secondary to inattention. Inattention happens as a natural human phenomenon and cannot be reasonably expected to disappear completely. Introducing the automation of processes such as labeling biopsy specimen containers can reduce potential slips. 3 Finally, the documentation of errors helps to increase their awareness and prevent future occurrences.
Institutions with a formal plan for documenting and handling errors experience less errors than their peer institutions.20 As a result, our institution has adopted a record for tracking errors and engages in periodic meetings to address them. Having an institutional plan for documenting errors is an important step in error prevention and quality improvement.
F I G U R E 6 Example of a major diagnostic misinterpretation. The clinical diagnosis was lichen planopilaris versus frontal fibrosing alopecia in a 69-year-old female. The low power view of this punch biopsy shows a perifollicular lymphocytic infiltrate with "constricting" fibrosis at the isthmus level. The dermatopathologist initially diagnosed the findings as consistent with lichen planopilaris. In a subsequent incidental review of the case, the same dermatopathologist noticed the obvious numerous hyphae within the hair shaft, consistent with tinea capitis, rather than the secondary perifollicular fibrosis that was interpreted as lichen planopilaris. This case is an example of inattentional blindness with biases including diagnostic momentum, overconfidence, and premature closure.
An important limitation of our study is the lack of external validity in a single-institution study. Furthermore, one dermatopathology attending signs out all the specimens, further skewing the data. Patterns of error will differ in other institutions and outpatient clinics where different regulations and biopsy pathways are encountered.
Finally, the presented data is an underestimation of the true error rate. Diagnostic errors without significant adverse outcomes go unnoticed and are quietly absorbed by the system and patients.