Post-Bone Marrow Aspirate & Core Biopsy

Introduction

Evaluation of a bone marrow aspirate and a bone marrow core biopsy may provide valuable information about the status of the bone marrow, its ability to respond to correct abnormalities in the peripheral blood and/or to determine if there is infection, myelofibrosis, necrosis, neoplasia or other abnormalities. For optimal interpretation of the status of the bone marrow, a full blood count and peripheral blood film should be submitted at the same time as the bone marrow aspirate. A bone marrow biopsy should be collected at the same time as the bone marrow aspirate. There are times when a bone marrow core biopsy may be held pending the results of the bone marrow aspirate and processed if additional histologic evaluation is considered to likely be useful based on the bone marrow aspirate findings.

Patient Restraint

Bone marrow collections are typically performed under general anesthesia. In compliant animals it may be possible to obtain bone marrow samples with sedation and local anesthesia.

Reasons to Examine Bone Marrow

Bone marrow evaluation is indicated when peripheral blood abnormalities are detected. The most common indications are persistent neutropenia, unexplained thrombocytopenia, poorly regenerative anemia, or a combination thereof. Examples of proliferative abnormalities in which bone marrow examination may be indicated include persistent thrombocytosis or leukocytosis, abnormal blood cell morphology, or the unexplained presence of immature cells in blood (e.g., nucleated erythroid cells in the absence of polychromasia or a neutrophilic left shift in the absence of inflammation).

Bone marrow is sometimes examined to stage neoplastic conditions (lymphomas and mast-cell tumors); to estimate the adequacy of body iron stores; to evaluate lytic bone lesions; and to search for occult disease in animals with fever of unknown origin, unexplained weight loss, and unexplained malaise. Bone marrow examination can also be useful in determining the cause of a hyperproteinemia when it occurs secondarily to multiple myeloma, lymphoma, leishmaniasis, and systemic fungal diseases. It may also reveal the cause of a hypercalcemia when associated with lymphoid neoplasms, multiple myeloma, or metastatic neoplasms to bone.

In veterinary medicine, bone marrow aspirates are done more frequently than core biopsies. Aspirates are easier, faster, and less expensive to perform than are core biopsies. Bone marrow core biopsies require special needles that cut a solid core of material, which is then placed in fixative, decalcified, embedded, sectioned, stained, and examined microscopically by a pathologist. Core biopsy sections provide a more accurate way of evaluating marrow cellularity and examining for metastatic neoplasia than do aspirate smears, but cell morphology is more difficult to assess.

There are few contraindications for bone marrow aspirates and core biopsies. Restraint, sedation, and anesthesia (when used) generally pose more risks for the patient than the biopsy procedure itself. Post-biopsy hemorrhage is a potential complication in patients with hemostatic diatheses, but it rarely occurs. Hemorrhage may occur after the biopsy of animals with monoclonal hyperglobulinemia, but it is easily controlled by placing a suture in the skin incision and applying pressure over the biopsy site. Post-biopsy infection is also a potential complication, but it is highly unlikely to occur if proper techniques are used. The major contraindication to bone marrow aspiration and core biopsies is when they are unnecessary (e.g., the anemia is regenerative, or the cause of the neutropenia is recognized to be sepsis).

Reporting

The results of the bone marrow aspirate cytology and associated complete blood count are reported often within 24 – 48 hours. The core biopsy, if submitted can take 7 - 10 business days.

Post-Sampling

A pressure bandage may be placed on your pet’s leg when the intravenous catheter is removed to prevent bleeding at the site. Be sure to remove this bandage after one hour if still present at the time of discharge. It is normal for pets to be quiet following general anesthesia or heavy sedation. You may be prescribed analgesia for administration to your bed for pain as needed.

Once home, you may offer your pet small amounts of water. If no stomach upset is noted, this may be followed by a light meal. Although uncommon, some pets may experience a mild cough for several days following their anesthesia. If you observe any unusual behavior, or have any concerns, contact your veterinarian immediately. Animals having been under anesthesia may behave in an unpredictable manner for 12-36 hours following recovery. Animals may bite if confused or startled: use caution during this time and keep pets away from young children.

You may need to schedule an appointment with your veterinarian to discuss the results.

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