**2. Diagnostic errors and concordances in pathology**

thousands of hospitals and independent laboratories in the USA, other places from North America, and abroad to identify and describe various experiences. These studies investigate the frequency of errors occurrence: the laboratory participants submit data from the calculation of the normative rates of errors during the laboratory tests. This exchange of information occurs so this knowledge convinces laboratory to abandon practices and behaviors harmful

Some reasons may explain less attention to errors in medical labs when compared to other medical errors. The higher variability in error during laboratory testing, difficulties in screening all errors, and all steps involved in the total testing process (TTP) can help explain these facts. Besides that, the TTP is more complex and needs cooperation between several health institutions. Surprisingly, physicians and other interested people do not understand full aspects about the harmfulness of errors in laboratory medicine. In addition to that, it is unde-

The errors in pathology laboratory are so common that in a self-administered mailed survey with 260 practicing pathologists and 81 academic hospital laboratory medical directors, approximately 95% suggested the involvement of any error and only 48% of that professionals believed that current error reporting systems were adequate. Among the factors that might make it less likely that they would disclose a serious error to a patient, the most common was the possibility that the patient would not understand what he or she was being told (*n* = 84, 49.7%) and the physician would not be able to explain the error clearly to the patient (*n* = 68, 40.2%), according to the interviewees' perception. The majority of participants believed that minor and near misses needed to be disclosed to patients (*n* = 120, 72.3% and 34, 20.1%, respectively) [5].

Troxel stands that an expectation from the society of "zero diagnostic error" and the "zero error standard" supported by the US judicial system is unattainable for obvious reasons (6). Surgical pathology laboratory process is much more complex than highly mechanized processes with minimal human participation, such as clinical laboratory analysis. Meier [6] describes the pathology production process in 12 steps. The production process begins with the correct identification of the patients' samples (1), selecting tissue specimens (2), labeling and transport (3), and accession (4). The process continues with the description of steps involving receipt and sampling of specimens (5), fixing, embedding, and cutting section (6), mounting, staining the slides, and labeling them (7), and delivering them to surgical pathologists (8). The process continues at the pathologist's desk—with examining, collating, and interpreting slides (9) and examining the possibilities of ancillary tests or other information (10), the composition of reports, (11) and finally the receipt and interpretation of the report (12). Therefore, the surgical pathology report is a complex task with multiple steps in

Meier et al. [7] proposed a standardized error classification that until then did not exist in pathology. We describe four types of errors (defective identification, defective specimen, defective interpretation, and defective report), distributed according to the processing step in the laboratory. In the pre-analytic phase, they describe defective identification (patient, tissue, laterality, anatomic location) and defective specimen (loss of the specimen, erroneous in measurement or gross description, floaters, inadequate sampling, and the absence of

sirable for laboratory professionals to report and disclose data about errors [4].

in the process of laboratory tests [3].

90 Quality Control in Laboratory

which there is a possibility of error.

To discuss the errors in pathology, it is essential to conceptualize their goals. Pathology should provide a correct and complete diagnosis, in other words timely, useful, and understandable for the attending physician [8]. Since the goals of pathology are multifaceted, it is easy to understand that there are multiple possibilities for error. The result must be accurate, based on gold standards, and scientifically validated. But what is the gold standard of pathology? Morphology is subjective and affected by the observer's experience. Cytogenetic studies by in situ or molecular hybridization are not applicable to most diseases routinely found in surgical pathology. Therefore, the most appropriate is to determine the accuracy, as a measure of diagnostic adequacy; it suggests that most of the qualified pathologists will agree on a similar diagnosis when analyzing the same specimen. A major or unacceptable variation is the one that will have a great effect on therapy or prognosis, such as in classifying a benign tumor as a malignant one. A smaller, acceptable, or minor variation is the one that has no effect on the treatment that would alter the progression of the disease, with no effect on the prognosis, such as in some subclassifications of benign or malignant tumors. These definitions can be applied to the three pathology goals (correct, complete, timely) [8, 9]. The errors can be further divided into errors of accuracy, that is, how much of the released diagnosis represents the true pathological process and precision errors related to concordances among pathologists in the interpretation of a case [9].

Meier et al. [10] divided the errors of pathological reports into four categories: errors of interpretation, identification, the specimen, and related to the report. A study based on this classification evaluated 73 participating institutions of Q-PROBES with 1688 errors in 360,218 cases of surgical pathology, with a ratio of 4.7 errors/1000 cases. Rates were higher in institutions with pathology residency programs (8.5 vs. 5.0/1000, *p* = 0.01) or when a percentage of cases were reviewed after release (6.7 vs. 3.8/1000, p = 0.10). Interpretation errors were responsible for 14.6% of the cases, 13.3% were identification errors, 13.7% were related to specimen errors, and 58.4% errors were of other modalities. In general, more errors were detected by pathologists (47.4%) than by clinicians (22%). Incorrect interpretations and specimen errors were detected by pathologists (73.5% and 82.7%, respectively, with *p* = 0.001), while identification errors were more frequently detected by other physicians (44.6%, *p* = 0.001). The rates of identification errors were lower when the reports were reviewed by a second pathologist prior to their release (0.0 vs. 0.6/1000, *p* < 0.001), and errors related to the specimen were less reported when released after an intradepartmental review of more difficult cases (0.0 vs. 0.4/1000, *p* = 0.02) [11].

**1.** Misinterpretations: This category is divided into three subtypes that occurred in relation to two levels of diagnostic information. In the first subtype, the diagnostic conclusions described inaccurate information (false-positives or overcalls). In the second subtype, the pathologist failed to recognize or lost accurate information (false-negatives or undercalls). Both can occur at primary (such as changes between positive and negative status or between malignant and benign diagnosis) and secondary levels of diagnosis. The secondarylevel diagnosis refers to when the clinical context or prognostic implications depend on the

Errors in Surgical Pathology Laboratory http://dx.doi.org/10.5772/intechopen.72919 93

The third subtype is misclassifications that occur when the pathologist changes similar diagnostic categories, for example, the names of a soft tissue sarcoma, without primary diagnostic implications or secondary diagnostic information's modifying impact (the differently labeled sarcoma behaved biologically with the same degree of aggressiveness during

**2.** Misidentifications: contained four subtypes—patient identification (lacking or wrong); tissue designation (e.g., lung confused with liver); laterality specification; and anatomic

**3.** Specimen defects included five subtypes: lost specimens, specimens with inadequate sample volume or size, samples with absent or discrepant measurements, inadequately repre-

**4.** Report defects: Defects of three subtypes were observed. In the first subtype, missing or erroneous non-diagnostic information about practitioners involved in the case, procedure or dates in which the specimen was collected, or codes regarding the patient, procedure, or diagnosis, and so on. The second subtype may be dictated or typographical errors. Failure or aberrations in electronic formats or in the transmission of information in reports was

During the material reception, gross examination, and processing, there are many possibilities of error, from the exchange of samples or labels, absence or excessive cuts in the block, to cross-contamination with tissues foreign to the specimen included in the final slide. Cognitive errors, such as inadequate or incomplete macroscopic descriptions, inadequate representation of the lesion or of relevant areas necessary for its characterization, may also occur, and although some are beyond the pathologist's control, the responsibility falls directly on him,

Morelli et al. [14] described critical points in pre-analytical steps in a pathology laboratory of a leading hospital in Lombardy, Italy. In this work, 8346 histological cases were reviewed, for which 19,774 samples were made and from which 29,956 histologies were prepared. They identified 132 errors, such as accessioning (6.5%), gross dissecting (28%), processing (1.5%), embedding (4.5%), tissue cutting and slide mounting (23%), coloring, (1.5%), labeling, and releasing (35%). Some very common errors were not detected in this work: specimen mismatching and sample contamination in gross room; mismatching or loss of specimen in embedding, loss, exhaustion, or contamination of specimen; and damage or changes of samples on the slides

sentative sampling, and samples with absent or inappropriate ancillary studies.

pathologic diagnosis, which occurs in malignant tumors.

localization (e.g., skin of head misidentified as skin of hand).

the same treatment).

considered the third subtype of error.

with very serious damage to the patient [8].

Meier [6] describes why the comparison of discrepancy rates is difficult in six different steps between the initial diagnostic event and the review event. The first is the difference in the internal and external review. In the internal review, the diagnoses under scrutiny were originally performed in the laboratory, and pathologists in other practices performed an external review. Second, the pre-sign-out review was held before a report was issued. Post-sign-out review happened after the report had been released. Third, in conference reviews, several experts discussed information about diagnosis, prognosis, and treatment of the patient to reach an agreement. Some reviews were nonconference related. Fourth, in review performed by an expert, the exam was conducted by a specialist with extensive experience and knowledge in the field. The fifth difference was blinded and nonblinded reviews. In blinded revisions, the second pathologist had the same amount of information as the first one, and sometimes a blinded reviewer was given less case-specific information. The last difference was between focused reviews in which the examiner trained the diagnosis of specific types of cases and nonfocused revisions in which the pathologist evaluated a defined fraction of cases of various specimens or types of diagnoses.
