Automated Cell Counting (Exam 2)

Coulter Principle

An electronic method for counting and sizing particles.

Cells, suspended in a conducive fluid and flowing through small aperture, may be detected, counted, and measured by the changes in electrical resistance produced by those cells

Non-Cyanide Hemoglobin Analysis Method

method of hematology analyzer that is used to measure hemoglobin and perform cell counts

method rapidly converts blood hemoglobin to oxyhemoglobin

-capability of analyzing methemoglobin

DC Detection Method

method of hematology analyzer that is used to measure hemoglobin and perform cell counts

specific blood sample is aspirated, diluted, and sent to transducer. Transducer has an aperture with electrodes where the sample flows between that causes change in current resistance

- change detected as electric pulses to indicate cell size

Throughput

the amount of sample that can pass through the system in a given time

roughly 60

the amount of samples per hour that the KX-21N processes

Carryover

contamination of a specimen by the previous one

item in a line or collection that is carried over from one sample to the next

Coincidence

Statistical correction for cells going through the aperture more than one at a time

Linearity

Reportable range of values (how long an instrument can read and how high it can read)

CELLPACK

diluent reagent in the SYSMEX

CELLCLEAN

detergent reagent in the SYSMEX

Stromatolyser-WH

WBC/HGB lyse reagent in the SYSMEX

Purpose of calibrating instrument prior to running QC and patients

Checks accuracy of instrument and determine traceability of the measurement (help assure precise measurements prior to running control/patients)

set actual result parameters (make sure parameters set so control checks function so machine does what is supposed to)

Why controls run

confirm instrument is working properly prior to running pt samples

-helps to monitor and control analytical error

3 (normal, low, high)

the amount of levels of controls

intervals of QC performed

Dependent on facility and instrument

- some 24-hr, some every shift change, some every 8-hr

Background function on hematology analyzer

Check there is nothing dirty in the machine because want analyses as close to zero as possible

Parameters that are measured in automated cell count

WBC - direct count of cells

RBC - direct count of cells

Hgb - direct measure of lysed blood

Hct - calculated

MCV - derived from RBC histogram

MCH - calculated

MCHC - calculated

PLT - derived from platelet histogram using 2-20 microns

RDW - displayed in bell-shaped curve in histogram

MPV - mean platelet volume

Calculated parameters in automated cell count

MCH - (Hgb x 10)/RBC

Hct - (RBC x MCV)/10

MCHC - (Hgb x 100)/Hct

whole blood

type of specimen in the hematology analyzer

steps of workflow in hematology analyzer

1) Aspiration: sucks up specimen

2) Delivery: pneumatics help pull sample through the tubing to each area for testing

3) Sensing: each area senses sample as it moves through the tubing and testing area

4) Analysis: performs function of hemoglobin lyses and cell count of specimen, prints results

5) Background: spits out wastes

6) Rinse: cleans itself by flushing diluent through sample after every run

1.0 - 99.9 x 10^3/uL

linearity range for WBC

1.0 - 6.6 x 10^6/uL

linearity range for RBC

0 to 20 g/dL

linearity range for Hgb

50 to 140 fl

linearity range for MCV

25 to 700 x 10^3/uL

linearity range for platelets

how results flagged by instrument when abnormal results

Parameter flags (H or L/arrows/positives or negatives)

Backlighting/Highlighting of error

Delta checks

Delta checks

quality control that allows for detection of clinically significant changes in laboratory results

large differences between two close blood draws

comparison of two sets of results from the same patient, based on specific criteria, as a quality improvement error by the laboratory

analyzer flags displayed at bottom of report

WBC - leukocytosis or atypical lymph

RBC - dimorphic population, microcytosis

PLT - clumping, thromobocytopenia/thrombocytosis

Parameters increased by presence of leukocytosis

RBC - small leukocytes counted as RBC

Hgb - WBC elevation causes turbidity = increase in Hgb

Hct - Turbidity due to elevated WBC results in falsely increased Hct

Parameters affected by cold agglutinin

RBC - decreased

WBC - increased

Hct - decreased

Cold agglutinin

RBCs stuck together --> analyzer reads as WBC

Can be fixed by heating specimen at 37C for 15-20 minutes

platelet aggregation

clumping together of platelets in the blood that results in a decreased platelet count

Five questions the MLS must ask

Are results within normal range?

Are results linear?

Are there any flags/codes present?

Do the Hgb and Hct match? MCHC okay?

Do results make sense? Possible and compatible with life?

Pre-analytical errors

Check patient label

Analytical errors

Check reagents

Check instrument systems

Run correction procedures

Check peripheral blood smear (clumping or agglutination)

Rerun, either whole or diluted

Check tube for clots

Hemolysis

Post-analytical errors

Normal results (send to chart)

Delta check

Review diagnosis and history of patient

Redraw specimen

11.5 - 14.5%

Normal RDW range

two peaks of bell curve

RBC histogram for a patient who recently had a transfusion

Scatterplot

name of graph that displays distribution of WBC showing volume vs light scatter