Why does it take so long to get the pathology diagnosis results?

1 Day 1 (24 hours)

①Scan registration:

First, the surgical specimen is scanned and registered in the pathology department to generate a unique pathology number. Just like each ID card corresponds to a person, each specimen corresponds to a pathology number.

② Source:

Standardized pathological sampling is performed by pathologists or specialized specimen sampling physicians. Because the specimens are fixed in 10% neutral formalin, this is why every specimen sampling physician is fully armed when sampling, and tears and snot will flow if you are not careful. The smell of formalin and xylene used to be the smell of the pathology department. Now the conditions have improved a lot, but we still have close contact with them every day. The specimens will be representatively cut into tissue blocks of 1.5 cmx1.5 cmx0.3 cm in size. Every pathologist can master superb knife skills, and everyone has the painful lesson of having their hands cut.

During the sampling process, the physician also needs a description staff to help record the detailed appearance of each specimen and the appearance of the lesion, which can be regarded as a small essay! Each case has its own unique features, and each unique feature may be an important clue for the diagnosis of the disease. In addition, the description staff also needs to prepare the sample box for the physician to ensure that each precious tissue block is placed in a neat small box.

Generally, puncture specimens need to be fixed with formalin for about 4 to 6 hours, and large specimens need to be fixed for 12 to 72 hours. Large specimens that are not sufficiently fixed cannot be sampled on the same day. Sampling in advance may lead to the final inability to diagnose. As the saying goes, more haste makes waste, and it is the same principle.

③Hanging basket:

The collected tissue blocks will be placed in a machine for fixation, dehydration, transparency and wax immersion. This process takes a whole night and is called "hanging basket".

At 6 o'clock every evening, the pathology technician on duty starts ringing the bell to remind the physician to hang the basket. Before hanging the basket, the physician will check the number of pieces with the description staff and print a paper version for the technician to check the next day. Hanging the basket late will affect the next day's film output time, so slow hands are always disliked!

2 Day 2

This day is a chance for technicians and teachers to show their talents.

④Embedding:

The fixed, dehydrated, transparent and wax-impregnated tissue blocks are taken out and placed in an embedding frame filled with melted paraffin to embed into wax blocks. This is a process in which the tissue and the embedding agent are melted into one and then cooled rapidly. This is also very technical. For example, when embedding hollow organs such as the stomach and intestines, special attention should be paid to the direction, otherwise the full layer of the tissue cannot be well observed.

⑤ Slicing:

The pathologist puts the wax block on the slicer and cuts each tissue into 3~4 um slices, and then quickly puts these slices into a container filled with alcohol with a small brush; in a large hospital, a pathologist cuts thousands of slices a day on average. For each slice, one hand needs to shake the slicer 3~4 times. The whole process is to work with the head down, shaking thousands of times a day. Therefore, many pathologists suffer from severe cervical spondylosis and elbow joint disease. Unfortunately, this is not like cutting lamb slices. Until now, there is no machine in the world that can replace this work.

⑥ Scoop slices:

The assistant scoops up the tissue slices and places them on a pathology glass slide.

⑦ Dyeing:

The slides were then dewaxed, cleared with xylene, and stained.

⑧Seal the film:

The stained slides need to be sealed with coverslips. Fortunately, there are fully automatic instruments to replace manual work in these two steps, greatly speeding up the preparation process.

At this time, a beautiful pink and blue slice is considered to be successfully produced and can be handed over to the pathologist for observation under the microscope. The whole process is comparable to the production of a work of art. It is often afternoon at this time. The hospital's pathology department produces 2,000 to 2,400 HE slices every day, not to mention 400 to 500 frozen slices, 2,000 immunohistochemical slices, and slices for consultation from other hospitals.

⑨Preliminary diagnosis by first-line pathologist:

After complicated film preparation, we can finally see the true appearance of the lesion under the microscope!

On the day the films were released, frontline doctors began to "bury their heads in a study". These 3,000 or so slices will be distributed to five frontline doctors for preliminary diagnosis.

First, let the frontline doctors make a preliminary diagnosis, which can not only train the diagnostic experience of young doctors, but also reflect the multi-level review system. Each film is reviewed by at least two people, which can greatly reduce the incidence of low-level errors. After that, the frontline doctors will generally hand over all the slides to the second line on the third or fourth day. The boards for the pathology department to put the slides are generally 20 per board, so each doctor has about 30 boards, which are as high as a mountain when stacked up. In addition, they often have to carry them back and forth from the technical room many times, which is really a real "brick mover".

3 Days 3-7

⑩Audit Report:

After the frontline doctors write the initial diagnosis, these 3,000 slides are handed over to six second-line pathologists for final review.

Second-line doctors have heavier tasks. They have to look at every slide and every lesion carefully, and they have to directly review cases that can be reviewed.

Pathologists must have eagle eyes and must always maintain a high level of concentration. If they lose focus, they may let a monster go, which may cause immeasurable losses to the patient.

Therefore, pathologists often work very late, and it is common to work until 8 or 9 o'clock in the evening. Some teachers often live in the department and regard the department as their home. Because they often stare at the microscope, their eyes will become dry and astringent, and at night they will be red like a little rabbit and full of bloodshot. Some people say that pathologists' eyes are a bit dull, probably because they have lost their luster under strong light for a long time.

⑪Printing and issuing report:

As mentioned above, pathology specimens sent on the same day will be reviewed by the second-line physician on the 3rd to 7th working day at the earliest. The pathology report can be printed on the afternoon of the 3rd or 4th working day after receipt at the earliest (usually for small specimens, large specimens need to be fixed overnight and will be at least one day late).

After that, a dedicated person will distribute the paper report to each ward or outpatient clinic. Now the information system is much more advanced. Four hours after the pathologist prints the report, the clinician and the patient can see the result on the electronic medical record system or mobile phone.

⑫Difficult cases:

Further testing is required based on the pathology doctor's instructions for additional gross sampling, re-slide preparation, immunohistochemistry, special staining, FISH, molecular testing, etc.

⑬Pathology doctor’s instructions:

Immunohistochemistry and special staining take a whole day, and FISH and gene rearrangement take a week. These are all laboratory work, which is very rigorous. If you add or subtract one minute, the results will be unreliable and not conducive to diagnosis.

⑭ Particularly difficult cases:

After the pathology order is executed, it must be submitted to a third-line physician or general practitioner for consultation and discussion to obtain accurate results.

Pathological diagnosis is just like clinical diagnosis. Sometimes there are detours. If the pathological doctor cannot complete the first round, then the second and third rounds of diagnosis will be completed. If the immunohistochemistry results do not provide any clues, molecular testing will be used instead. In rare cases, molecular testing still cannot provide a definite conclusion. Therefore, it takes 7 to 14 working days, or even longer, to diagnose difficult cases.

No matter how complicated the disease is, only by finding out the truth about the disease can we treat it accurately. We are always working hard to make a faster and more accurate diagnosis!

Xiehe Star Project-Peking Union Medical College Hospital Pathology Department Intelligent Disease Treatment Team

*Some of the pictures in this article were produced with the assistance of AI, and the photos were provided by Wang Yuan and Shi Jie

Editor: Liu Yang and Zhao Na

Proofread by Li Na and Li Yule

Producer: Peng Bin

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