The Mythical Land of the Lab

So, working at a medical laboratory, I see a lot of stuff to do that people generally don't think about. They know tissue goes there and that results come back, but not a whole lot else. So, I thought that it might be fun to do a full chronicle of the journey from hospital to result. There's a lot of steps that I'm guessing you never would have thought about. Maybe some of you will find it informative, maybe it'll be boring. Either way, I think it's pretty cool, so I'm going to write about it. Obviously, there is going to be a lot of variation from specimen to specimen, lab to lab, but here's what I have experienced.

1. The courier picks up a bunch of specimens and their paperwork from the hospital. Sometimes these are designed medical couriers, sometimes specimens are literally sent through FedEx. It depends on the specimen, what tests are ordered, and who ends up giving the final diagnosis.

2. When the specimen arrives at the lab, it is accessioned. This was what I did at my old job. Patient data is entered into the computer and verified to match the paperwork and it's given a case number.the case number follows everything associated with that patient's specimen through the lab. Tissue block are printed with the case number. These things are impossible to describe, so here's a picture:

3. The specimen is grossed. This means a Pathologist's Assistant (PA) cuts a bit of the tissue of interest whole describing the specimen into a recording that will later be transcribed and sent with the final report. The bit of tissue is placed into the blocks and loaded onto the processor.

4. The specimen is processed. Processing is basically cooking. In fact, early processing was done in a microwave. Not kidding. Processing removes the formalin and water while preserving the cell structure. Processing can take anywhere from a couple hours to half a day or more, depending on the tissue.

5. Once processing is complete, the blocks are given to an embedder, a person who arranges the tissue and embeds it in paraffin, like this:

The tissue is in that little button that sticks out. On the right is the mold they put it in the make them all uniform

5. Slides are printed for all of the stains that the tissue requires. All specimens that I see at Inform get Hematoxylin and Eosin (H&E) and some get special stains on top of that.

6. The tissue is given to a microtomist for cutting. Microtomy is the ultimate deli slicing. The tissue is cut to a width of 5 microns and laid on the slides, like this:

This part takes special training, obviously. I avoid walking past the microtomists because I walk fast and the gust of wind can mess them up. That is how sensitive these things are. Pity the microtomist with hay fever.

7. Slides are loaded onto various stainers depending on what stain is ordered. A stainer has a mechanical arm that moves the slides through a series of buckets of reagents and dyes. All of the stains are pre-programmed, so we just load them, start them, and wait. Some stains take only 45 minutes, some take 3 hours, it depends on which one. Slides are then given a coverslip to protect the tissue.

8. When the stains come off the stainer, they are then matched up in the computer by case number with their tissue locks to ensure that we have everything that was ordered and that it was done correctly. This is called Matchmaker at Inform, I don't know what other labs do.

9. Blocks are archived, put into storage on case the doctor asks for more slides, and the slides are imaged. Imaging is where the slides are looked at and any areas of interest are highlighted and put into a description that will also go on the final report.


10. Slides are given to distribution and sent to the appropriate pathologist with the report to be read and give a result. That result is sent to the doctor and the doctor gives it to the patient.


And all of this happens in less than two days. Labs generally run all hours of the day, and they are busy places. There are a lot of gaps of waiting for things to finish like the processing and staining, but there's always something going on. There are a lot of people who influence the result of every specimen, and we have to do it with a less than 1% error rate.

So yeah, that's the life of a skin biopsy, or a colon polyp, or whatever you get sent to the lab. I hope you found this interesting and informative. I like my job, so I enjoy talking about it like this. There, you can say you learned something today!