Different kinds of specimens can be used at the histopathology laboratory for investigations. Some of the common examples are:
- Trabeculectomy specimen removed after anti-glaucoma surgery
- Vitrectomy, membranectomy removed after vitrectomy procedures
- Lens removed after cataract surgery
- uterus after a hysterectomy
- large bowel after a colectomy
- Tonsils after a tonsillectomy.
Biopsy portion of the tissue can also be used to establish the diagnosis. This can be obtained from:
- Bone marrow
- Choroid or retino-choroidal tissue
- breast lump
Things to keep in mind when receiving pathology specimens
- The specimen should be properly labeled, which means it should include the following information:
- The patient’s name
- The patient’s age
- The type of material or specimen
- Surgery date and time
- Doctor’s name
- Adequate clinical summary with clinical diagnosis.
- Proper fixation in proper preservative.
Specimen’s preservation
- Tissue should be preserved in the appropriate fixative as soon as possible because drying causes artifacts.
- For routine surgical specimens, 10% neutral buffered formalin is used, 70% alcohol for IOLs, and 2.5 percent glutaraldehyde for electron microscopic study.
- The approximate volumes of fixative should be used. That is, Make sure the fixative volume is 15 to 20 times that of the tissue volume. Make sure the grossed sections are thin, no more than 3 mm thick. To avoid depletion, change formalin solutions frequently throughout the process.
Time of Fixation
- Small specimens (5 mm biopsy) : 12 hours
- Globes, exenterated specimens, or large specimens measuring more than 20 mm : 48 hours
- Smears of fluid specimens: 95% alcohol Fixation should be completed as soon as possible.
Sending out the specimen
If a specimen must be sent for a second opinion, avoid sending in a large volume at fixative. The fixed tissue can be transferred to a smaller volume (approximately twice the size of the specimen) or wrapped in formalin-soaked gauze.
How to order for a frozen section
In the case of adnexal tumors, a frozen section is usually performed. To keep the cryostat machine ready, the Histopathology lab must be notified at least 6 hours before surgery. The results of such a study are ready in 20 to 30 minutes.
Numbering of specimen accession number
Tissues that arrive at the laboratory are assigned an accession number. The accession number is printed on both the requisition form and the container in which the specimen is delivered. Once the tissue is taken for processing, this accession number follows it through all stages.
Reference
- Sankara Nethralaya’s Manual of Medical Laboratory Techniques P. 380 – 400
- Mayoclinic via https://www.mayoclinic.org/diseases-conditions/cancer/in-depth/biopsy/art-20043922
- Fixation and Processing Freida L. Carso, https://webapps.cap.org/apps/docs/store/PUB123_Histologic_Sample.pdf
