Confusion—specimen mix-up in dermatopathology and measures to prevent and detect it
Authors: Weyers Wolfgang 
Published: May 2014

Maintaining patient identity throughout the biopsy pathway is critical for the practice of dermatology and dermatopathology. From the biopsy procedure to the acquisition of the pathology report, a specimen may pass through the hands of more than twenty individuals in several workplaces. The risk of a mix-up is considerable and may account for more serious mistakes than diagnostic errors. To prevent specimen mix-up, work processes should be standardized and automated wherever possible, e.g., by strict order in the operating room and in the laboratory and by adoption of a bar code system to identify specimens and corresponding request forms. Mutual control of clinicians, technicians, histopathologists, and secretaries, both simultaneously and downstream, is essential to detect errors. The most vulnerable steps of the biopsy pathway, namely, labeling of specimens and request forms and accessioning of biopsy specimens in the laboratory, should be carried out by two persons simultaneously. In preceding work steps, clues must be provided that allow a mix-up to be detected later on, such as information about clinical diagnosis, biopsy technique, and biopsy site by the clinician, and a sketch of the specimen by the technician grossing it. Awareness of the danger of specimen mix-up is essential for preventing and detecting it. The awareness can be heightened by documentation of any error in the biopsy pathway. In case of suspicion, a mix-up of specimens from different patients can be confirmed by DNA analysis.
Every year, hundreds of thousands of pages are devoted to diagnostic problems in medicine. In books and medical journals, physicians constantly share their experiences, advance criteria for diagnosis, and alert to diagnostic pitfalls. One tremendous pitfall, however, probably the greatest of them all, is hardly ever mentioned, namely, specimen mix-up.
The true size of that pitfall is unknown. There are only few articles about that subject and most deal with individual cases. This is not surprising because specimen mix-up would not occur if it could be recognized reliably and studied systematically. In laboratory medicine, analysis in the early 1970s of 5200 control cases smuggled into routine examinations revealed an error rate of 3.5%. The most common of those errors, occurring in 0.89% of all cases, was a specimen mix-up [1]. By contrast, in a survey conducted at hospitals of many countries, the rate of specimen mix-up was estimated to be about 0.5% [2]. The discrepancy between those data suggests a huge dark figure of cases.
In addition to the dark figure whose true size, naturally, is shrouded in the dark, other factors hamper a systematic analysis of mistakes in the assignment of specimens. Among them are different criteria employed in studies dealing with mistakes in laboratory medicine, some studies including only cases of specimen mix-up that were not recognized and corrected immediately, others many other types of mistakes, ranging from loss of specimens to incomplete labeling of them that could be amended easily [3,4]. Even inappropriate biopsies and incorrect interpretation of reports by clinicians have been dubbed “laboratory errors,” in accordance with the definition of such errors as “any defect from ordering tests to reporting results and appropriately interpreting and reacting on these.” [5] Moreover, data from one hospital or laboratory cannot be transferred readily to another, even if the same criteria are employed.