SIP
Subject Title: Histopathology
Topic: Tissue processing
Hi all. I had been attached to a histopathology lab. My SIP consist of 5 components, they are: tissue processing, embedding, microtomy, special staining and cytology. I am posted to the tissue processing station for the first month of my SIP. In this station, my main task is to receive specimen, label specimen and assist the pathologist in recording and labelling of cassettes.
Everyday in the morning, once we received the specimens, we will label the specimens and the request form with a bar coded biopsy number. The sample will then be carried to a room where trimming and examination of specimen is performed. Small specimens, such as appendix, gall bladder, bone marrow core, tonsils, cornea or gastric biopsies will be trimmed or passed into a cassette by a medical technologist. The large and complex specimens such as liver, kidney, intestine, breast, uterus, eye ball or femoral head will be examined and trimmed by a pathologist.
Lab personnel who are in charge of trimming or passing of small specimens into cassettes must make sure that the bar code and the specimen name on the bottle are matched with the request form before commencement of any procedure. Once confirmed, details of the specimen such as number of tissues in the bottle and type of tissue will be recorded. Measurements will also be taken. Specimens will then be trimmed into a smaller pieces using a surgical blade and pass into a cassette. For bone specimen, a bone saw is used to cut the specimen into smaller pieces and is then decalcify before processing. For prostate, whole mount is necessary (a bigger version of tissue block), as the whole entire piece of prostate will be dissected and submitted for investigation. For specimens such as gastric biopsy (about 0.1cm x 0.1cm in size), which are very small, will be coloured with ink and place in a filter paper. The purpose of using ink is to allow the person who is doing embedding to see the tissue clearly so that he/she can transfer the tissue into the mould. The filter paper will prevent lost of tissue during processing. Inks are also used by pathologist to indicate the orientation of the tissue. After trimming, if there is excess tissues, the excess tissues will be set aside for storage and indicate on the requisition form as tissues with reserve.
After passing of tissue into cassettes, the cassettes containing the tissue will be fixed in 10% neutral buffered formalin until all other tissues are ready to be processed. The pH of the formalin will be check daily to ensure that the pH is around 6.8-7.2 as neutral pH will minimize formalin precipitation. New formalin is changed at least twice a week. The principle of fixation is to stop autolysis. Fixatives form cross linkages between protein, thus preserved the tissue's in vivo structure.
The lab used an enclose tissue processor for tissue processing. An enclosed system means that tissues will remains stationary in a closed chamber and processed until the procedure is completed. Tissue processing consists of 3 components:
1) Dehydration: remove water from tissue using graded alcohol
2) Clearing: replace alcohol with an agent that is miscible with wax. Xylene is most commonly used, but some new machine use isopropanol instead of xylene, which make the working environment better.
3) Impregnation: tissue infiltrated with embedding medium.
Different types of tissue will have different processing time. For small fragment of tissues or biopsies, the processing time is usually 2-3 hours. For tissues of normal sizes, the processing time is usually set at 16 hours.
Apart from processing, I had also learnt some safety aspects in a lab, such as how to deal with chemical spillage, and the protocol as follow:
1) Isolate the area of spillage
2) Wear personal protective equipments, such as glove and mask
3) Choose an appropriate spillage kit available in the lab
4) Circulate the spillage with the spillage kit and max them
5) Scoop the spillage, and place the mixture in a bag and tighten it.
I think I will stop here first. Enjoy your SIP!
Wing Fat
TG01
Topic: Tissue processing
Hi all. I had been attached to a histopathology lab. My SIP consist of 5 components, they are: tissue processing, embedding, microtomy, special staining and cytology. I am posted to the tissue processing station for the first month of my SIP. In this station, my main task is to receive specimen, label specimen and assist the pathologist in recording and labelling of cassettes.
Everyday in the morning, once we received the specimens, we will label the specimens and the request form with a bar coded biopsy number. The sample will then be carried to a room where trimming and examination of specimen is performed. Small specimens, such as appendix, gall bladder, bone marrow core, tonsils, cornea or gastric biopsies will be trimmed or passed into a cassette by a medical technologist. The large and complex specimens such as liver, kidney, intestine, breast, uterus, eye ball or femoral head will be examined and trimmed by a pathologist.
Lab personnel who are in charge of trimming or passing of small specimens into cassettes must make sure that the bar code and the specimen name on the bottle are matched with the request form before commencement of any procedure. Once confirmed, details of the specimen such as number of tissues in the bottle and type of tissue will be recorded. Measurements will also be taken. Specimens will then be trimmed into a smaller pieces using a surgical blade and pass into a cassette. For bone specimen, a bone saw is used to cut the specimen into smaller pieces and is then decalcify before processing. For prostate, whole mount is necessary (a bigger version of tissue block), as the whole entire piece of prostate will be dissected and submitted for investigation. For specimens such as gastric biopsy (about 0.1cm x 0.1cm in size), which are very small, will be coloured with ink and place in a filter paper. The purpose of using ink is to allow the person who is doing embedding to see the tissue clearly so that he/she can transfer the tissue into the mould. The filter paper will prevent lost of tissue during processing. Inks are also used by pathologist to indicate the orientation of the tissue. After trimming, if there is excess tissues, the excess tissues will be set aside for storage and indicate on the requisition form as tissues with reserve.
After passing of tissue into cassettes, the cassettes containing the tissue will be fixed in 10% neutral buffered formalin until all other tissues are ready to be processed. The pH of the formalin will be check daily to ensure that the pH is around 6.8-7.2 as neutral pH will minimize formalin precipitation. New formalin is changed at least twice a week. The principle of fixation is to stop autolysis. Fixatives form cross linkages between protein, thus preserved the tissue's in vivo structure.
The lab used an enclose tissue processor for tissue processing. An enclosed system means that tissues will remains stationary in a closed chamber and processed until the procedure is completed. Tissue processing consists of 3 components:
1) Dehydration: remove water from tissue using graded alcohol
2) Clearing: replace alcohol with an agent that is miscible with wax. Xylene is most commonly used, but some new machine use isopropanol instead of xylene, which make the working environment better.
3) Impregnation: tissue infiltrated with embedding medium.
Different types of tissue will have different processing time. For small fragment of tissues or biopsies, the processing time is usually 2-3 hours. For tissues of normal sizes, the processing time is usually set at 16 hours.
Apart from processing, I had also learnt some safety aspects in a lab, such as how to deal with chemical spillage, and the protocol as follow:
1) Isolate the area of spillage
2) Wear personal protective equipments, such as glove and mask
3) Choose an appropriate spillage kit available in the lab
4) Circulate the spillage with the spillage kit and max them
5) Scoop the spillage, and place the mixture in a bag and tighten it.
I think I will stop here first. Enjoy your SIP!
Wing Fat
TG01
posted by BloodBank.MedMic.Haematology @ 2:55 PM
10 Comments:
At July 22, 2007 at 3:13 PM ,
J.A.M.M.Y.S said...
Hey Wing Fat
Simple question for you.
What type of maintenance is done on the cutting utensils such as the surgical blades and bone saw? How do you ensure that after you cut one specimen no excess tissue from the blade would be found on a different specimen and result in cross contamination?
Thanks
Azhar TG01
At July 22, 2007 at 6:18 PM ,
VASTYJ said...
Hey wing fat =)
Y isopropanol instead of xylene used, will make the working environment better ?
vaLerie XD
At July 22, 2007 at 8:47 PM ,
ALsubs said...
hihi
hey i have one quest for you askig out of curiosity.. u mentioned that The pH of the formalin will be check daily to ensure that the pH is around 6.8-7.2 as neutral pH will minimize formalin precipitation. what if the the formalin precipitates? and u have used that precipitated formalin? wat corrective action will be taken??
Vino
At July 22, 2007 at 10:23 PM ,
royal physicians said...
heya wing fat...i have a few questions for u...1st is why is the trimming done by two different people depending on the size and why must you store the excess tissue?....and i have the same qn as valerie also how does isopropanol make working environment better because i've handled with it too and the smell is very strong....tt's all...hope u r enjoying ur SIP:)
nur zahirah (tg02)
At July 23, 2007 at 9:11 PM ,
J.A.M.M.Y.S said...
hiya, why does normal tissues require a longer time compared to small tissues during processing? Then how do you store them if you don't have much time and have to go back home?
Thanks ya
Michelle
At July 23, 2007 at 9:19 PM ,
The Lab Freaks said...
hey wing fat...
your lab sounds interesting...
out of curiousity... how does the specimen comes to you? and does it come in a whole part or just a portion?
~Jeremy~
TG01
At July 25, 2007 at 12:19 AM ,
VASTYJ said...
hi wing fatt.. juz curious.. u asked abt ink for prostrate gland processing.. wad type of ink is it?
Jia Hao
At July 28, 2007 at 8:29 PM ,
BloodBank.MedMic.Haematology said...
To Azhar:
The pathologist or med tech will clean up the blade or bone saw after trimming of one specimen. Since the blades are disposable, we can also change a new blade if necessary.
To Valerie:
isopropanol is less toxic
To vino:
Formalin precipitations will be formed on the tissue, and can only be seen under microscope. The corrective action as follow:
1)make a new section
2)before staining, let the section stand in saturated alcoholic picric acid solution for 1-3 hours
3)wash well in running water, and stain as usual
To Zahirah:
Because med tech are not train on how to dissect organs, therefore trimming of large and complex one must be done by doctors. The small one usually do not require much trimming. Therefore are directly pass into a cassette by med tech.
the excess tissue allow pathologists to re-examine and cut extra sections to support his/her diagnosis if necessary.
isopropanol is less toxic.
To Michelle:
chemicals can infiltrate small tissues faster(simply because they are small), thus required lesser time to complete processing.
All tissues in the lab are processed a fixed time schedule, and will never be processed in an irregular time interval.Before we go home, we will immediate start processing the tissue, tissues will be processed overnight and will be ready on the next day when we come to work. Therefore we dont have much problem about time.
To Jeremy:
there is something like a conveyer that brings the tissues to the lab, and the staff will bring it to the reception room. The samples, whether comes in whole or in part, is depend on the type of surgery. sometime they remove the whole thing, sometime jux a small portion...etc
To Jia Hao:
i also not quite sure.... The ink they use will stay in the tissue forever, it wont come off even after processing. i will try to find out more about it....
At July 30, 2007 at 12:17 AM ,
VASTYJ said...
hi wing fat!
for the specimen that is dyed with ink, after embedding and microtomy, is the slide still stained again with some other dyes?
Ying Ying
TG01
At August 4, 2007 at 10:44 PM ,
BloodBank.MedMic.Haematology said...
To ying ying:
Yes, the slides will still go under routine H & E.
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