Blood Smear and Bone Marrow

AspirateVarsha Narasimhan

CBL Group E211/29/2010

glass microscope slide coated with a thin layer of venous blood

stained with a dye, usually Wright’s stain which can display both basophilia and eosinophilia

used to supplement information from automated hematology analyzers (blood cell counters)

Blood Smear1,2

Maxwell Wintrobe’s wedge slide technique:Blood Smear: Procedure2

Step 1. Place a small drop of venous blood on a glass microscope slide, using a glass capillary pipette or a wooden applicator stick

Step 2. Position a spreader slide at ~30 degree angle and slowly draw it toward the drop of blood.

Step 3. Bring spreader slide in contact with the drop of blood so that capillary action draws the blood across the edge of the spreader slide.

Step 4. Pull the spreader slide further out, leaving a thin layer of blood behind.

Step 6. After drying for about 10 minutes, the slide can be stained manually or placed on an automated slide stainer.

The zone of morphology is the area of optimal thickness for LM examination

Features suggestive of Anemia and/or jaundice Sickle cell disease Thrombocytopenia or neutropenia Lymphoma Myeloproliferative disease Disseminated intravascular coagulation Renal failure Retinal problems Some bacterial or parasitic disease Disseminated nonhematopoietic cancer General ill health suggestice of mononucelosis or other

infection or disease

Clinical Indications for a Blood Smear3

“several myelocytes and metamyelocytes and left shifted myeloid series, increased platelets of

varying sizes and shapes.”

The Patient’s Results

Normally, blood contains band cells and neutrophils with 2-5 lobes, with <2% myeloid precursors.

In patients with CML, promyelocytes, myelocytes and metamyelocytes proliferate abnormally and are present in larger numbers in the blood and bone marrow.

Thrombocytosis is observed in 30% - 50% of patients in the chronic stage of CML, occasionally at levels higher than 1,000 x 109/L.

Absolute monocytosis is not uncommon, although monocyte percentage is typically low (<3 percent) on CML

The total absolute lymphocyte count is increased (mean: approximately 15 x 109/L) in patients with CML at the time of diagnosis as a result of the balanced increase in T-helper and T-suppressor cells. B lymphocytes are not increased.

4, 5, 6

Patient is sedated and area around anterior iliac crest is anesthetized and sterilized

Needle is inserted into marrow and aspirate is drawn into syringe◦ Bloody liquid containing light-colored particles of

marrow .5 -1 mm in diameter• Aspirate can be mounted for microscopy as is,

stained, and/or mixed with EDTA as an anticoagulant and centrifuged to concentrate cells

Bone Marrow Aspirate7

For disorders like iron deficiency anemia, thalassemia, and acquired and inherited hemolytic anemia, blood and lab tests may be enough

Marrow biopsy is superior to aspirate in assessing marrow cellularity and diagnosing infiltrative marrow diseases

Marrow aspirate is useful in very specific cases, like suspected megaloblastic anemia as a result of vitamin B12 or folic acid deficiency, or surveillance followup of leukemia patients in apparent remission.

Uses of Bone Marrow Analysis7

“hypercellular, with increased M:E ratio. The myeloid series is shifted to the left, with 5% blasts. Megakaryocytes are increased.”

The Patient’s Results

CML bone marrow is often hypercellular, with bone ; hematopoietic tissue takes up 75 to 90 percent of the marrow volume, with fat markedly reduced

M:E is myeloid to erythroid precursor ratio; granulopoeisis increases. Erythropoeisis also decreases because erythroid precursor maturation is blocked at the basophilic erythroblast stage.

Bone marrow blast levels are 5% or less in the chronic phase of CML

Megakaryocytes are platelet precursors; elevation in bone marrow aspirate is fairly common in CML and is a symptom of thrombocytosis. 8,9

1. http://www.pathology.vcu.edu/education/PathLab/pages/hematopath/pbs.html

2. http://www.bu.edu/histology/m/append02.htm3. Bain, B. (2005) Diagnosis from the Blood Smear. New

England Journal of Medicine 353:17, 1862-18624. Cramer, E. “Hematopoeisis.” Lecture. 19 Nov 2010. 5. http://

www.cml-info.com/de/healthcare-professionals/about-cml/symptoms-of-cml.html

6. http://www.accessmedicine.com/content.aspx?aID=61249977. http://www.accessmedicine.com/content.aspx?aID=61068578. http://

www.accessmedicine.com/content.aspx?aID=2891657&searchStr=leukemia%2c+myelocytic%2c+chronic

9. http://www.accessmedicine.com/content.aspx?aID=6124913

Sources