Henry Ford once said, “There are no big problems - there are just a lot of little problems.” When it comes to cross contamination, there is no single source of contamination, nor will a solitary solution perfectly eliminate all potential concerns. Cross contamination is a complex issue that requires one to break the problem down into smaller, more manageable parts.
To begin with, one must define the term, cross contamination, and determine how frequently labs are experiencing this problem. Cross contamination is simply extraneous tissue that is present on a microscope slide but is from a different specimen. This can be as simple as a few squamous cells sloughing off a lab tech’s fingers onto the microscope slide, or as significant as malignant tissue in a tissue block from a different patient entirely. To answer the question of how frequently cross contamination occurs, there are several published articles that state that this happens between one and three percent of the time, whereas one source cited its frequency as high as eight percent.
While there are many sources of cross-contamination, the most common sources are: surgeons/clinics, surgical pathology (grossing), tissue processors, embedding, and microtomy.
As one can imagine, cross contamination is a very serious problem with potentially severe consequences. Assigning a patient a faulty diagnosis could result in unnecessary additional procedures; not to mention the liability on an organization if the wrong diagnosis is rendered.
Tried & True Solutions
The basic recommendations for preventing cross contamination are far too numerous for one blog post, but here is a great article I recommend to help you determine the weak points of your laboratory:
Hodgson A, Shang YM, Boulianne P, Downes M, Hwang D, Slodkowska E. A Practical Approach to Investigating Cross-Contamination in the Anatomical Pathology Laboratory. International Journal of Surgical Pathology. 2020;28(7):700-710.
Another excellent resource worth checking out is the Practical Guide to Specimen Handling in Surgical Pathology, created by CAP and NSH.
New Solutions to Consider
Labs that process many different specimen types have a slight advantage over labs that specialize in single specimen types (i.e. dermatology, GI, etc.) when it comes to troubleshooting as they are able to separate specimens while they are being grossed in. Labs that do not have this luxury may consider utilizing ink as a means of differentiating similar specimen types. By dying the tissue specimens in various colors, one can easily differentiate specimens from each other.
A large degree of potential issues is simply solved through automation. When human error is removed, cross contamination is naturally reduced. Although not an exhaustive list, here are a few examples of current novel instrumentation: Sakura’s Tissue-Tek AutoTEC a120 Automated Embedder, Axlab’s AS-410M Auto Slide Preparation System, and Clarapath’s SectionStar. These are worth considering. One must be mindful, however, that while automation successfully removes human error, it may also introduce new variables that one’s lab may not have considered.
Digital Pathology
Pantanowitz et al. (2020) wrote a lovely article on utilizing digital pathology as a means of rapidly identifying the source of a contaminant. This solution is highly useful and will hopefully be adopted by many laboratories. Be encouraged to read the full article here:
Pantanowitz L, Michelow P, Hazelhurst S, et al. A Digital Pathology Solution to Resolve the Tissue Floater Conundrum. Archives of Pathology & Laboratory Medicine. 2020;145(3):359-364. doi: https://doi.org/10.5858/arpa.2020-0034-oa
Conclusion
As we all strive to eliminate cross-contamination, let’s remember the words of William A Foster: “Quality is never an accident; it is always the result of high intention, sincere effort, intelligent direction and skillful execution; it represents the wise choice of many alternatives.”
Written By: Jeremy Johnston, HT(ASCP), QIHC(ASCP)
#2023#LaboratoryOperations#Blog