An article published by the Cleveland Clinic's Dr. Mary Bronner, outlines the steps involved in a biopsy procedure in great detail. It turns out there are 18 different steps involved, and the number of times a particular tissue sample changes hands is significant. The steps to this extremely complex process are explained below (note: numbers have been added by the author):
"Considering the numerous medical professionals involved in processing a tissue sample from the patient to the pathologist reviewing it microscopically, it is truly a marvel that so few errors occur. Consider that from the patient, a biopsy sample or surgical resection specimen is initially (1) handled by the treating physician using carefully cleaned biopsy and surgical tools that have been used previously to obtain many other patients' samples. One or more nurses or other assistants assist the physician in (2) getting the tissue sample into a properly labeled specimen container. The specimen container is (3) batched with many other containers and (4) transported to the pathology laboratory. There, the specimen is (5) accessioned into the pathology computer system and is (6) assigned a unique surgical pathology identifier. Next, the paperwork and specimen container are (7) processed by a pathology assistant, resident, or pathologist who removes the specimen from the labeled container and examines and describes the tissue grossly. The tissue is (8) dissected by carefully cleaned instruments that also are used to dissect many other patients' samples. The specimen is (9) divided among a number of tissue cassettes, small plastic containers, which are (10) labeled individually with the surgical pathology number and a unique block number. The tissue cassettes have holes in them to permit flow of the various processing fluids required to process the tissue chemically into a final wax tissue block. Many hundreds of different patients' cassettes are (11) placed into a common chemical bath for this processing stage. Rarely, a tissue fragment from one patient can exit its cassette and enter through the cassette holes of another patient's block to become part of this second patient's block. A histotechnologist uses clean forceps, which are cleaned and used subsequently on many other patients' specimens, to (12) pick up the wax-infused tissue fragments from the processing cassettes and place them into the final wax tissue block that will be used to section the actual histologic slides. Another histotechnologist (13) sections 5 μm slices on a razor blade affixed to a microtome. These thin wax slices are (14) floated onto a carefully cleaned water bath, which has had many other patients' wax slices previously floating in it. Floating allows slices to flatten and be (15) transferred onto a glass slide, which has been hand-labeled by the histotechnologist. The slide later receives a permanent computer-generated slide label that is (16) affixed to the slide by another technician. Finally, all of the slides on any given patient's procedure are (17) assembled with the accompanying paperwork and (18) delivered to the pathologist for diagnostic interpretation. A mistake leading to inadvertent tissue contamination can occur at any one of the above logistically complex processes.[1]"
In learning more about this process, it is impossible not to see just how many opportunities there are for error. Even with quality assurance checkpoints in place, the misidentification or switching of biopsies from time to time is inevitable. With the introduction of the know error® specimen security system with unique patient code and DNA identity confirmation, we are able to catch switching errors that would be otherwise undetected by existing quality assurance systems. The know error® system identifies biopsy identity switches before a patient suffers an adverse outcome (i.e., under treatment/overtreatment).
To learn more about the know error® specimen security system, visit www.knowerror.com.
[1] DNA Fingerprinting Analysis for Specimen Identification http://referencelab.clevelandclinic.org/DBSearch/TestDetail.asp?ID=2676
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