Identification of blood elements using inverted microscopy
AssigneeRoche Diagnostics Hematology, Inc.
InventorsJames W. Winkelman, Milenko J. Tanasijevic, David Zahniser
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Abstract
A method of identifying the elements of a blood sample including placing an aliquot of blood on a transparent substrate such as a coverslip. The blood is allowed to stand and the cells to settle to form a layer or matrix. Inverted microscopy is used to identify the elements in the sample. Various forms of illumination may be used alone or in multiple combinations. The method improves the accuracy due to homogenous distribution of formed elements in the wet drop or aliquot, simplifies the method, lowers the cost of the test and results in a shortened analytical cycle time.
Claims25
A method of preparing and examining cells from a sample of blood, said method comprising the steps of:
- preparing the cells for examination by:
- placing an aliquot of whole blood on a surface of a transparent material, wherein the aliquot of whole blood comprises a distribution of cell types including red blood cells, white blood cells and platelets, and further wherein said aliquot of whole blood is placed on said surface of said transparent material without removing any of the cell types from the aliquot of whole blood;
- and
- allowing the cells to settle onto the surface of the transparent material for a period of between 10 seconds and two minutes to form a monolayer of cells;
- and
- examining from below the transparent material at least a portion of the monolayer to determine a count of a specific cell of the whole blood, wherein the examining comprises:
- directing illumination light to be incident on a surface of the transparent material at a first angle to the surface and obtaining a first image of the cells, wherein the first angle is selected to preferentially display a first subset of the cell types in the first image relative to the other cell types;
- and
- directing illumination light to be incident on a surface of the transparent material at a second angle to the surface and obtaining a second image of the cells, wherein the second angle is selected to preferentially display a second subset of the cell types in the second image relative to the other cell types,
- wherein the first and second subsets comprise at least one different type of cells.
Dependencies are inferred from the claim text.