The hematology part of the pathophysiology exam
About the exam
The pathophysiology final has 5 parts:
- 1st theoretical question (from the first semester)
- 2nd theoretical question (from the second semester)
- analysis of an ECG tracing
- lab problem
- microscopical examination of a hematological smear
The exam usually starts with hematology. This means you get an unlabeled
or coded hematological smear together with the questions you draw.
You have an opportunity to examine it as you get prepared for the
exam, then you need to form an opinion about the smear. This
practically means you have to make a diagnosis. You get no further
information about the smear when you get it, not even if it is
a blood or bone marrow preparation. The examiner may ask further
questions in connection with the smear:
- tell the name of individual cells in the microscope (cell identification)
- you may be asked to find a specific cell type in your preparation (e.g.
a myelocyte)
- list/speak about the clinical features, diagnostic tools, normal values
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What smears am I supposed to recognize?
You can certainly get the following ones:
| peripheral blood | bone marrow |
|---|
| normal | normal |
| acute leukemia | acute leukemia |
| CML | megaloblastic anemia |
| CLL | plasmocytoma |
In addition to these although not very likely, you might get
a left shifted periphery, lymphocytosis, infectious mononucleosis
in peripheral blood.
You will never get a smear from which the diagnosis
is uncertain e.g. CML in the bone marrow, plasmocytoma in the
periphery, etc.
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If I need to recognize only 8-10 smears, I can learn
that in an afternoon, right?
Not at all. While it is true, that the number (8-10)
of smears is much less then the number of sections that you had to
learn from histology or histopathology, you are likely to have
about as much problem with the 10 smears as with the dozens of
histological sections. There are two reasons for this:
- The study of blood and bone marrow smears is a special area
of cytology, it is not histology. A histological section is easier
to recognize, because the structure of the tissue (the spatial
relationship of cells) provides a lot of information. Examination
of a cytological specimen (where we have no data about the spatial
relationship of cells) is always more difficult than the same thing
histology.
- Histological sections from two persons with the same disease
are usually similar, while smears taken from two acute leukemia
cases can be totally different. Even if you make preparations at
subsequent times from the same patient, you may see strikingly
different pictures.
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How can I fail?
If the examiner finds out you don't know some important
hematological reference value (e.g. hemoglobin concentration,
RBC count, WBC differential) you can be pretty sure you get a
1 for the hematological part of your exam. You will get a 1
if you can't list the erythroid or granulocyte cell line, or
don't know their morphological characteristics. Depending
on the opinion of the examiner, you are likely to get a 1 if
you don't know enough about the classification, clinical
characteristics or laboratory diagnosis of malignant
hematological diseases.
You are better off, if you recognize the smear you get
at the exam, but all is not lost if you don't, you may have
a chance to change your opinion. The examiner usually gives
a clue for you in this case by showing a few characteristic
cells or some other way. The clues of course may or may not be
enough for someone...
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László L. Tornóci
Copyright © Inst. Pathophysiology,
Semmelweis Medical University