Fixation on Histology

Preanalytical- The Most Focused Phase of the Lab

  

There are different factors that negatively affect the quality of samples in the histology laboratory which we collectively call pre-analytical error. It is mostly caused by lack of knowledge, attitude and practice of sample management, miscommunication, and accountability.

The most common types of biological samples in the Anatomic Pathology (AP) laboratories are histological samples (biopsies and surgical resections), cytological samples (exfoliative and fine needle aspiration cytology (FNAC)) and clinical autopsies. Due to the unique and irreplaceable nature of most specimens for AP examination, every effort should be made to ensure that they enable a correct and complete diagnosis. According to Clinical Laboratory Improvement Amendments (1988), AP laboratories are included in the highly complex test category, which requires strict quality control and quality assurance policies and procedures. Several studies reported that most failures occur in the pre-analytic and post-analytic segments, the first being more prone to error.

Preparation of surgical specimens for histopathological examination requires a sequence of step-wise passages, from the biopsy removal up to the paraffin block. The time interval between surgical intervention and proper fixation of the removed specimen is defined as “ischemia time” and is crucial, since ischemia allows activation of tissue enzymes, autolysis, and degradation of proteins and nucleic acids. In our case, at my lab in Ethiopia, there were many occurrences where we received biopsies unfixed, in water saline, denatured alcohol, concentrated formalin, etc. from the surgical department.

An article from Dr. Sheila Criswell, HTL (ASCP), QIHC (ASCP), UTHSC on Fixation on Histology, titled “Evaluation of Bone Marrow Biopsies” on June 1, 2021, shows that bone marrow biopsies/aspirates are unique specimens in that a portion of each sample is sent to four different areas of the lab for evaluation: Flow cytometry, histology, hematology and cytogenetics. As the sample is collected, it requires different types of treating before analysis. In our case there is a discrepancy in body fluid samples that are collected for chemistry and cytology analysis. Due to lack of sample management, most of the samples are sent to one of the labs without taking a portion for analysis. We will encounter a problem where a portion of cervix sample collected with Surepath method must be distributed to cytology and molecular analysis. Miscommunication or no standard procedure for communication makes the tissue for frozen section forced to stay aside without fixation (Michel solution) until the cryostat reaches the desired temperature as it was switched on late due to miscommunication between operating theatre and AP lab.

In response to the new requirements, more and more laboratories will have to adapt their activities and implement, control, and standardize the procedures associated with the pre-analytical phase. Each laboratory should create a dedicated unit, with specific equipment and specialist staff. There should be a plan to prepare a training and follow the Standard Operating Procedure (SOP) for both communication, and training. A continued competency assessment (CA) is important for the accountability of the staffs responsible for the sample in the pre-analytical phase.

Written by Giorgis Yeabyo, MS, Abeba Consultancy Services

References

1- Roque et al.: Preanalytic errors in anatomic pathology: study of 10,574 cases from five Portuguese hospitals, Researchgate, De Gruyter, 2015

2- Manfred D. Christian W. Gianni B• Moritz von W, Pre-Analytics of Pathological Specimens in Oncology, Springer, 2015

3- Sheila Criswell, Evaluation of Bone Marrow Biopsies, Fixation on Histology, National Society of Histotechnologists (NSH) USA, June 1, 2021

4- Susman et al, The role of the pathology department in the preanalytical phase of molecular analyses, Cancer Management and research, Dovepress, 2018:10: 745–753


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