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WBC estimate from smear.

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In the context of general equities, this describing a buy interest in which a dealer is asked to offer stock, often involving a capital commitment. Antithesis of in touch with.
 guidelines or a formula to help determine an estimated of the white blood cell (WBC WBC white blood cell; see leukocyte.

white blood cell

n stands for white
) count in whole blood from the peripheral smear smear (smer) a specimen for microscopic study prepared by spreading the material across the slide.

Pap smear , Papanicolaou smear see under test.

A When properly performed, the estimated white blood cell count white blood cell count,
n a diagnostic clinical laboratory test to determine the number and types of leukocytes present in a measured sample of blood. Overall the normal number of leukocytes ranges from 5000 to 10,000/mm3.
 from a stained peripheral blood peripheral blood Cardiology Blood circulating in the system/body  smear is a useful tool to verify flagged results from automated hematology analyzers. Automated WBC counts are prone to interferences from conditions such platelet clumps clump  
1. A clustered mass; a lump: clumps of soil.

2. A thick grouping, as of trees or bushes.

3. A heavy dull sound; a thud.

, large platelets, lysis-resistant red blood cells Red blood cells
Cells that carry hemoglobin (the molecule that transports oxygen) and help remove wastes from tissues throughout the body.

Mentioned in: Bone Marrow Transplantation

red blood cells 
, or nucleated nucleated /nu·cle·at·ed/ (noo´kle-at?id) having a nucleus or nuclei.

Having a nucleus or nuclei.


having a nucleus or nuclei.
 red blood cells. (1) Flagged results require a blood-smear review by a technologist prior to reporting.

Various formulas exist for estimating the WBC count from a peripheral blood smear. Given the various instrumentation and slide-preparation techniques found in different laboratories, each lab should develop its own formula correlating the automated WBC count with the blood-smear findings. This can be done by following these steps:

1) Run a number of patient blood samples, (we recommend 30 samples), through the automated hematology analyzer;

2) Examine the same group of patients' stained blood smears and count the number of WBCs seen per field (20x, 40x, or oil, whichever you like to choose.) Count 10 fields and average them; and

3) Determine the WBC estimation factor (conversion factor) of each sample. (The WBC estimation factor equals the automated WBC count divided by manual WBC counts per field. (4)) Calculate the average estimation factor from the 30 samples.

Once the WBC estimation factor has been determined, the estimated WBC count equals the average manual WBC count per field multiplied by the estimation factor. For example, if the WBC estimation factor equals two, and there are four WBC per 40x field, the WBC estimate is 8x[10.sup.9]/L.

The December 2001 "Q & A" published on the College of American Pathologists' website offers a procedure for developing the WBC estimation factor. (2)

--Eric Nutt, MT(ASCP ASCP American Society of Clinical Pathologists. )

--Guang Fan, MD, PhD

Hematology Service

Department of Pathology

Oregon Health and Science University

Portland, OR


1. Stiene-Martin EA, Lotspeich-Steininger CA, Koepke JA. Clinical Hematology: Principles, Procedures, Correlations. Philadelphia, PA: J.B. Lippincott Co; 1992.

2. Sandhaus L. Q & A. CAP Today. December 2001. Available at:

Edited by Daniel M. Baer, MD

MLO's "Tips from the Clinical Experts" provides practical, up-to-date solutions to readers' technical and clinical issues from a panel of experts in various fields. Readers may send questions to Dan Baer by e-mail at
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Title Annotation:Answering your questions; white blood cell
Author:Baer, Daniel M.
Publication:Medical Laboratory Observer
Geographic Code:1USA
Date:Feb 1, 2007
Previous Article:Training deficiency.
Next Article:Blood drawing after transfusions.

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