Fixation: Difference between revisions
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==Immersion== | |||
<!-- Also in Pathology for medical students article | <!-- Also in Pathology for medical students article | ||
-->Within an hour after removal from the body,<ref>{{cite web|url=https://www.uclahealth.org/pathology/workfiles/Education/Residency%20Program/Gross%20Manual/Mastectomy%2006.03.20.pdf|title=Breast pathology grossing guidelines|website=UCLA Health|accessdate=2021-09-09}}</ref> tissue samples should generally be placed in vessels with | --> | ||
[[File:Adipose tissue with crumpling artifact due to insufficient fixation.jpg|thumb|Adipose tissue with crumpling artifact due to insufficient fixation.]] | |||
Within an hour after removal from the body,<ref>{{cite web|url=https://www.uclahealth.org/pathology/workfiles/Education/Residency%20Program/Gross%20Manual/Mastectomy%2006.03.20.pdf|title=Breast pathology grossing guidelines|website=UCLA Health|accessdate=2021-09-09}}</ref> tissue samples should generally be placed in vessels with enough fixative to allow them to lie freely in the solution.<ref name=kvast>{{cite web|url=http://www.svfp.se/foreningar/uploads/L15178/kvast/hud/Handlaggning%20av%20hudprover%20%20provtagningsanvisningar%20utskarningsprinciper%20och%20snittning%2020150325.pdf|title=Handläggning av hudprover – provtagningsanvisningar, utskärningsprinciper och snittning (Handling of skin samples - Instructions for sampling, cutting and incision|author=Katarzyna Lundmark, Krynitz, Ismini Vassilaki, Lena Mölne, Annika Ternesten Bratel|accessdate=2019-09-09|website=KVAST (Swedish Society of Pathology)}}</ref> The standard fixation fluid is generally 10% neutral buffered '''formalin''', which is roughly equivalent to 4% formaldehyde.<ref>{{cite web|url=https://microscopy.duke.edu/guides/paraformaldehyde-formaldehyde-formalin|title=Paraformaldehyde, Formadehyde and Formalin|website=Duke University|accessdate=2019-12-17}}</ref> The ratio of tissue:formalin should be 1:5<ref>{{cite web|url=https://www.rcpa.edu.au/getattachment/d6f7f095-e8b7-45eb-8dcb-6a9d9bd5a88a/Fixation-of-Tissues.aspx|title=Fixation of Tissues}} Approval Date: August 2016, August 2020. Review Date: August 2024|website=Royal College of Pathologists of Australia</ref> to 1:10<ref name="pmid22483550">{{cite journal| author=Buesa RJ, Peshkov MV| title=How much formalin is enough to fix tissues? | journal=Ann Diagn Pathol | year= 2012 | volume= 16 | issue= 3 | pages= 202-9 | pmid=22483550 | doi=10.1016/j.anndiagpath.2011.12.003 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22483550 }} </ref>.<ref name="pmid22483550">{{cite journal| author=Buesa RJ, Peshkov MV| title=How much formalin is enough to fix tissues? | journal=Ann Diagn Pathol | year= 2012 | volume= 16 | issue= 3 | pages= 202-9 | pmid=22483550 | doi=10.1016/j.anndiagpath.2011.12.003 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22483550 }} </ref> | |||
The | ==Duration== | ||
The duration depends on tissue thickness, where formalin will penetrate and fix the tissue at ~1 mm/hour.<ref>{{cite web|url=https://rhslab.pitt.edu/drop-info/how-submit-tissues-embedding|title=How to Submit Tissues for Embedding|website=University of Pittsburgh, Starzl Transplantation Institute}} Revised 04/19/21</ref> | |||
==When not to use formalin== | |||
{{Formalin exceptions}} | |||
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{{General notes}} | |||
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Latest revision as of 20:36, 28 November 2022
Author:
Mikael Häggström, M.D. [note 1]
Immersion
Within an hour after removal from the body,[1] tissue samples should generally be placed in vessels with enough fixative to allow them to lie freely in the solution.[2] The standard fixation fluid is generally 10% neutral buffered formalin, which is roughly equivalent to 4% formaldehyde.[3] The ratio of tissue:formalin should be 1:5[4] to 1:10[5].[5]
Duration
The duration depends on tissue thickness, where formalin will penetrate and fix the tissue at ~1 mm/hour.[6]
When not to use formalin
The main exceptions to using formalin are mainly:
- Intraoperative consultation.
- Suspected crystals, such as a tophus or other specimen suspicious for gout versus pseudogout. These should be sent in alcohol or dry, since formalin will dissolve the crystals.
- Suspected lymphoproliferative disorders, such as lymph nodes (or other lymphoid aggregates) with a suspicion of lymphoma, where samples are generally put in a special solution for flow cytometry.
- Need for genetic testing, such as some cases of products of conception.
- Cytology specimens, which are preferably sent fresh (such as in red top tubes) to be processed within a few hours. If processing may be after a few hours, put tubes on ice, or add 50% alcohol.[7]
- Need for microbiology evaluation, mainly bacterial culture. For potentially infectious workups, check with the microbiology lab if they have the tissue they need before putting the specimen in formalin.
- Need for immunofluorescence, such as immune complex-mediated disease, where specific preservation will give better test sensitivity.[8]
If you don't know, and if you cannot soon get in touch with anyone who can guide you, specimens can generally be stored in a fridge in the meantime, even overnight if it is late (but make sure to follow-up as soon as possible in the morning). Until then, don't put the specimen in formalin and don't freeze the specimen.
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Further reading: |
Notes
- ↑ For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.
Main page
References
- ↑ . Breast pathology grossing guidelines. UCLA Health. Retrieved on 2021-09-09.
- ↑ Katarzyna Lundmark, Krynitz, Ismini Vassilaki, Lena Mölne, Annika Ternesten Bratel. Handläggning av hudprover – provtagningsanvisningar, utskärningsprinciper och snittning (Handling of skin samples - Instructions for sampling, cutting and incision. KVAST (Swedish Society of Pathology). Retrieved on 2019-09-09.
- ↑ . Paraformaldehyde, Formadehyde and Formalin. Duke University. Retrieved on 2019-12-17.
- ↑ . Fixation of Tissues. Approval Date: August 2016, August 2020. Review Date: August 2024|website=Royal College of Pathologists of Australia
- ↑ 5.0 5.1 Buesa RJ, Peshkov MV (2012). "How much formalin is enough to fix tissues? ". Ann Diagn Pathol 16 (3): 202-9. doi:. PMID 22483550. Archived from the original. .
- ↑ . How to Submit Tissues for Embedding. University of Pittsburgh, Starzl Transplantation Institute. Revised 04/19/21
- ↑ . How to send fluid and make good cytology slides. Tufts University.
- ↑ Mubarak M, Kazi Javed I, Kulsoom U, Ishaque M (2012). "Detection of immunoglobulins and complement components in formalin fixed and paraffin embedded renal biopsy material by immunoflourescence technique. ". J Nephropathol 1 (2): 91-100. doi:. PMID 24475396. PMC: 3886135. Archived from the original. .
Image sources