The page below is a sample from the LabCE course Technical Preparation of Bone Marrow Specimens for Histological Assessment. Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

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Direct aspirate smear

Particle crush step 1

Aspirate: Optional Immediate Bedside Smear Preparation

The aspirate samples may be immediately processed at the bedside for direct smears. Direct aspirate smears (shown in top image on right) are prepared in the same manner as a peripheral blood smear, by placing a small drop of aspirate/particles on one end of the slide and smeared with another. This smear is used to review the bone marrow morphology. Immediate preparation allows for the best morphology with minimal artifact, assisting the pathologist in providing a diagnosis for the patient.
Another immediate slide preparation at the bedside could include a particle crush smear. To prepare this slide, particles from the aspirate are pipetted on the center of one slide, as shown in the lower image on the right (step 1). Another slide is placed on top, as shown in the image below, to "crush" the particles (step 2).

Particle crush step 2

The crushed particles are then dispersed as the slides are pulled apart from one another, as shown in the image below (step 3). Once the remainder of the non-heparinized aspirate forms a clot, wrap the clot in biopsy paper and place into formalin for fixation and subsequent processing (as discussed in Bone Marrow Clot Preparation).

Particle crush step 3

Aspirate blood samples should immediately be transferred into blood collection tubes. Commonly, heparinized aspirate is placed into one or two EDTA (purple/lavender-top) tubes, one to two sodium heparin (green-top) tubes, and one to two acid-citrate-dextrose (ACD) yellow-top tubes. The EDTA tube should be used to process the reminder of the aspirate for slide preparation. The other EDTA, sodium heparin, and the ACD tubes can be used for ancillary studies such as cytogenetics, flow cytometry, and molecular diagnostics as indicated by the testing laboratory.
Note: Do NOT use a lithium heparin (green-top) tube. Lithium heparin is toxic to the aspirate cells and is not acceptable for ancillary studies.