Fixation: Difference between revisions

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{{General notes}}
==Immersion==
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 the correct fixing solution, with a volume that allows 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>  
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[[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 main exception to formalin are mainly:
==Duration==
*A '''[[tophus]]''' or other specimen suspicious for gout versus pseudogout should be sent in alcohol or dry, since formalin will dissolve the crystals.  
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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