Figure 12B. After the needle is well-seated, vigorously rock it back and forth in two or three directions (red arrows) to
cut the core and retain it within the biopsy instrument. Then withdraw the needle with a rapid twisting motion.
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Remaining perpendicular to the cortex, insert the needle in the same manner as for the aspiration, but remove the stylet once
the needle has purchase in the cortex (Figure 12A). After removing the stylet, continue to advance the needle into the marrow for about 1 cm, depending on patient size. After
the needle is firmly seated, rock the needle vigorously and rapidly back and forth in two or three directions (Figure 12B). There will be little or no obvious lateral motion in the needle if it is securely seated. Then slightly retract, redirect,
and slightly advance the needle to cut the core, which will be retained within the needle bore. Remove the biopsy needle from
the bone with a continued twisting motion. Expel the core from the needle by placing the wire in the cutting end of the Jamshidi
biopsy needle and gently pushing the small piece of cortical bone and marrow retrograde from the needle.
Figure 13. A gross specimen of a bone marrow core biopsy (unfixed). Note the white cortex (right) and red marrow (left).
Shorter core samples (0.75 cm or more) are acceptable as long as sufficient red marrow is present. Marrow with decreased erythroid
activity may be pale. The marrow tissue often appears gelatinous before formalin fixation.
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If the biopsy is performed correctly, the sample will have a white end (cortex) and a red strip (marrow) (Figure 13). A core that is 0.75 to 1 cm long is sufficient. If the first attempt is unsuccessful, another attempt can be made adjacent
to the first. Before placing the sample in 10% buffered formalin for submission to a surgical pathology service, you can gently
roll it on a glass slide for cytologic samples if an adequate aspirate has not been obtained. Be careful not to crush the
sample, resulting in a nondiagnostic biopsy sample.
CONCLUSION
This review is intended to provide the tools you need to become proficient in acquiring diagnostic bone marrow samples. Once
confident in your skills, you may be surprised how often you will include this modality in your diagnostic work-up to provide
high-quality care for your patients.
Kristen R. Friedrichs, DVM, DACVP
Karen M. Young, VMD, PhD
Department of Pathobiological Sciences
School of Veterinary Medicine
University of Wisconsin
Madison, WI 53706
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