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1068 Bone Marrow Aspiration and Core Biopsy

• Although bone aspirations have less risk of For biopsy: Postprocedure
pathologic fracture, there is a lower likelihood • While wearing sterile gloves, remove stylet • Apply direct pressure and ice for 10-15
VetBooks.ir for special stains or immunohistochemistry is in working order and seal has been broken; • Ensure appropriate analgesics are available
minutes to reduce hematoma development/
from the biopsy needle to ensure that needle
of definitive diagnosis and does not allow
bleeding.
replace stylet.
(IHC) on biopsy samples.
• Avoid using too small of a needle or biopsy
blade. CAUTION: ensure nerves and vessels
instrument. Although bigger instruments will • Tent the skin, and make a stab incision with because patient will likely have pain after
procedure.
remove/damage larger pieces of bone, they do not course in the chosen area. • If there is concern about pathologic fracture,
also result in more tissue for diagnosis. • Take biopsy needle in dominant hand, and radiograph sample site.
• If soft tissue prevents easy contact with bone, work through subcutaneous tissues until
cut-down and dissection of vital soft tissues contact is made with underlying bone. Alternatives and Their Relative
before aspiration or biopsy may be warranted. Seating (similar to a bone marrow biopsy) Merits
For aspiration, use radiographs to find an is likely not possible due to cortical loss in • Open biopsy: more invasive with higher risk
ideal location of cortical lysis/diseased bone diseased bone. After the needle is advanced of infection, but specimens will likely be
to biopsy. Avoid major muscles. into diseased bone/tissue, remove stylet, larger.
• Minor complications include pain, bleeding, and continue advancing biopsy needle. A • Amputation (if lesion on a limb): considered
infection. clockwise-counterclockwise motion with part of standard of care for primary bone
firm, downward pressure may be necessary. malignancies; also necessary for pathologic
Procedure ○ CAUTION: due to weakness of diseased fractures. Because amputation will limit treat-
• Place sedated/anesthetized animal in recum- bone, using index finger and thumb ment options (radiation, bisphosphonates,
bency with easiest access to diseased bone, as as a buffer will help prevent penetra- limb spare), thoroughly discuss differential
identified by radiographs. An approximate tion through the bone or damage to diagnoses and prognosis with owner.
measurement of the thickness of the lesion surrounding soft-tissue structures. The
should be made from radiographs to antici- biopsy needle should be palmed (butt Pearls
pate desired depth of needle penetration. of the needle in palm, needle shaft held • Larger-bore needles are helpful to penetrate
• The skin over the lesion is clipped and asepti- firmly between index finger and thumb) through cortical bone for aspiration.
cally scrubbed. Local analgesia is infused so that the tips of the thumb and index • Steadying/buffering biopsy needle with index
subcutaneously and deep to the periosteum. finger pinching the needle shaft act as a finger and thumb prevents clinician from
• Brief aseptic scrub is repeated after local buttress. overpenetration and potential tissue damage
analgesia injection; clinician then dons • After sufficient advancement (deep penetra- during biopsy.
gloves. tion into the diseased bone), slightly rock • Adequate pain medications will allow patients
For aspiration: the needle in the same circular direction to to remain comfortable while waiting for
• An 18- or 20-gauge needle is inserted into the break bone free from attachments. cytology or biopsy results.
diseased bone and a woodpecker technique • Continue to rotate (slight rock) needle as it • Use radiographs to find best location to
is repeated until a sufficient sample has been is removed from the bone. A plug of tissue aspirate or biopsy. Necrotic areas (complete
obtained or blood begins to fill the hub of should be seen in biopsy needle. absence of bone) may not be diagnostic,
the needle. • Tissue plug is removed using stylet inserted whereas sclerotic or proliferative areas may
• Remove needle, attach air-filled syringe, and in normograde direction (bone trocar) or be too dense to biopsy.
immediately disperse sample onto microscope retrograde (Jamshidi-type needle, which is
slides. If blood is visible in needle hub, place tapered at the tip) to push the tissue out AUTHORS: Brian K. Flesner, DVM, MS, DACVIM;
Deborah J. Tate, RVT, VTS
only a single drop of sample per slide. into the formalin jar. EDITORS: Leah A. Cohn, DVM, PhD, DACVIM; Mark S.
• An additional blank slide is used to make • Two or three samples are taken from one loca- Thompson, DVM, DABVP
smears; use care not to place too much tion to increase diagnostic yield. Skin sutures
pressure and smash the sample. may be necessary for larger skin incisions.

Bone Marrow Aspiration and Core Biopsy Bonus Material
Online

Difficulty level: ♦♦ • Staging of neoplasia: lymphoma (pp. 607 Equipment, Anesthesia
and 609) or mast cell tumor (pp. 632 and • Sedation, neuroleptanalgesia, or general
Synonym 634) most common anesthesia with local analgesia
Bone marrow aspiration (BMA) • Diagnosis of feline leukemia virus (FeLV) ○ Typical sedation: dexmedetomidine 5 mcg/
infection (p. 329) with suspicious clinical kg IM or IV with morphine 0.5 mg/kg
Overview and Goal presentation and negative peripheral test IM or IV
To obtain a sample of bone marrow cells for • Unexplained gammopathy ○ Typical general anesthesia: premedicate
cytologic (aspiration) and/or histologic (core • Infectious screening for fever of unknown with above sedation drugs, and induce
biopsy) analysis origin (p. 334) with propofol 6 mg/kg IV to effect;
maintenance with propofol as needed or
Indications Contraindications isoflurane gas
• Cytopenias without identifiable underlying • Contraindications to sedation or anesthesia ○ Local analgesia: 9 : 1 mixture of 2%
cause • Skin infection over bone marrow sampling lidocaine HCl to sodium bicarbonate;
• Abnormal blood cell number or morphology site 1-2 mL infiltrated subcutaneous to
on blood smear • Thrombocytopenia is not a contraindication periosteum

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