As many of you know, I had the opportunity to perform a
couple of bone marrow aspirates and biopsies last
semester as part of my practicum.  I thought I would
share with you some of the information we can elicit
from looking at a sample of someone’s bone marrow or an
actual chunk of bone…

Examining bone marrow is critical to assessing
hemotopoietic function (Trewhitt, 2001).  On the day
that you are performing the aspirate, peripheral blood
samples will also need to be collected so that accurate
comparisons can be made.  Typically, the posterior
superior spine of the iliac crest is chosen for both
aspiration and biopsy.  Evaluating both bone marrow and
biopsy samples enable you to look at the cellularity of
the marrow, as well as the nature of the cells.  

Bone marrow consists of a hematopoietic cell compartment
as well as a stromal compartment that supports the
proliferation of the blood cells.  Cellularity is an
estimate of the percentage of hemotopoietic components
and stroma in the marrow space (Trewhitt, 2001).  A
hypocellular marrow may occur in aplastic anemia or in a
marrow that is packed with leukemic cells.  In this
case, aspiration may not be possible and attempts result
in a ‘dry tap’, and performing a biopsy may be necessary
to evaluate cellularity.  

Some of the tests that are commonly performed (at least
in the oncology/hematology field) include flow
cytometry, which is used to analyze cell surface
markers, which is useful in screening leukemia’s and
following leukemia response to treatment (Trewhitt,
2001).  Cytogenetic testing may be done to screen for
chromosomal markers or abnormalities, such as the
Philadelphia chromosome in CML.  Molecular studies are
extremely sensitive and can recognize one abnormal cell
in one million (Trewhitt, 2001).  This may allow for
detecting residual disease after treatment, or it may
identify which genetic mismatches may be tolerable for a
patient who is looking for an unrelated bone marrow
donor.  Immunophenotyping is sometimes done, which is
really hard to explain, but basically looks where the
aberration occurs that differentiates the neoplastic
cell from the normal cells.

When you are actually doing the BMA/bx, there has to be
a representative from the lab there to prepare the
slides immediately upon receiving the samples.  There is
a lot of physical pressure but hopefully not too much
pain for the patient – sedation isn’t necessary, but
lots of freezing is!  Unfortunately, the pressure occurs
because you can’t obviously freeze past the periosteum,
so there will be some discomfort.  In pediatrics, the
actually perform this procedure under anaesthesia.  

One thing I learned is that some practitioners are
advocating the practice of bilateral bone marrow
examination – basically doing two tests on either hip to
decrease the incidence of false negatives.  In the one
study I looked at, the researchers evaluated 410 bone
marrow samples that were positive for malignancy (Wang,
Weiss, Chang, Slovak, Gaal, Forman, & Arber, 2002). 
11.7% of the samples detected unilateral disease
involvement – basically that BM bx done on one side of
their body had discrepant results with the results
obtained using the other side of the body.  This is a
little nerve-wracking to a hematology nurse…48 of the
410 patients stood to appear as though they did not have
bone marrow involvement, which can influence
dramatically the treatment you receive.  When it was
broken down by disease, the results were even more
appalling – the discrepancy rate was 39% for patients
with Hodgkin’s disease, and 29% for those with sarcomas
(Wand, Weiss, Chang, Slovak, Gaal, Forman, & Arber,
2001).  

Common practice in my area is to not do bilateral bone
marrow examinations, but if a physician is not confident
in the results he or she is seeing, proceeding to a
second test may occur.  To qualify the results of this
research, they are advocating for bilateral assessment
in NHL, Hodgkin’s disease, carcinoma, and sarcoma; they
did not find the results warranted bilateral examination
in acute or chronic leukemia, myelodysplasia (MDS), or
MM (which makes up the bulk of the diseases that we
treat on our unit, but it still is food for thought).

Anyhow, this is just a little snippet from my practice –
you guys are lucky this is a busy week, because I could
(and may still) inundate you with stories…if you hear me
say ‘back in the good old days…’ I suggest running
quickly in the opposite direction.

Take it easy everybody!

Lisa

PS – I was warned that when you are pushing through to
get the bone marrow aspirate site, it feels like you are
pushing through Rice Krispies – this is what I was told,
and for once, this was exactly how it felt.

References:  Trewhitt, K. G. (2001). Bone marrow
aspiration and biopsy: Collection and interpretation.
Oncology Nurses Forum, 28(9), 1409-1417. Wang, J.,
Weiss, L. M., Chang, K. L., Slovak, M. L., Gaal, K,
Forman, S. J., & Arber, D. A. (2002). Diagnostic utility
of bilateral bone marrow examination: Significance of
morphologic and ancillary technique study in malignancy.
Cancer, 94(5), 1522-1531.