Automation of Urinalysis and Body Fluids Examination, Graff's Textbook of Urinalysis and Body Fluids
Time-saving equipment and equipment that can accommodate large numbers of samples have been developed for every area of the clinical laboratory. Automating laboratory procedures allow for better stan- dardization of test performance and reduce not only the turnaround time but also transcription errors. Automated equipment for performing urine and body fluid analysis takes the form of semiautomated or automated. Nearly each manufacturer of reagent strips has developed its own instrument. Some manufacturers have also developed automated systems for performing microscopic analysis on urine and/or body fluids. This chapter contains a brief explanation of the basic principles of some of these instruments.
RATIONALE FOR AUTOMATING URINALYSIS AND BODY FLUIDS
Significant sediment findings may be missed if laboratory protocols direct laboratory personnel to skip microscopic evaluation when negative reagent strips findings are obtained. Crystals, renal tubular epithelial cells, parasites, and yeast do not have chemical indicators present on reagent strips currently in use. These findings also do not always have other abnormalities present that would lead to the performance of a microscopic evaluation. In addition, interfering substances still do play a role in occasionally masking the presence of red blood cells (RBCs) and white blood cells (WBCs). Automation of the microscopic portion of the urinalysis not only helps detect unexpected sediment but also helps standardize the identification and enumeration of urinary sediment. Eliminating inaccuracies in manual timing of reactions and visual subjectivity of reagent pad color interpretation
helps make urinalysis more reliable and less dependent on the technologist. With automation, not much time is needed to perform a complete urinalysis than a dipstick screening only. Some laboratories do not perform a microscopic examination when dipstick findings are normal. This policy may be helpful in managing workflow in understaffed laboratories, but some significant microscopic findings may be missed.
AUTOMATED URINALYSIS SYSTEMS
Several brands of urinalysis automation are currently available. The current choices available include strip readers, semiautomatic strip readers, fully automated urine chemistry analyzers, automated urine sediment analyzers, and completely automated urine analyzers with both chemical and sediment analysis capabilities. Table 15-1 lists some of these urinalysis instruments currently available.
Semiautomated instruments require manual dipping of the reagent strip into the urine followed by placement on the instrument. Identification of the specimen is keyed in prior to sampling of the specimen. Instruments that fully automate reagent strip reading use a barcode-labeled specimen. Although sampling is automated, tubes must still be decapped prior to placement on these instruments. Automated urine sediment analyzers use similar barcode identification and specimen handling requirements. Reagent strip readers and sediment analyzers can be used in tandem for a fully automated urinalysis.
IRIS DIAGNOSTICS DIVISION
Iris Diagnostics Division of IRIS International Inc manu- factures instruments that provide semiautomation of urine chemistry and those that fully automate reagent strip reading and urine sediment analysis. The instruments can be used independently or in pairs for a complete urinalysis.
The AUTION MAX reads the specimen’s barcode, aspirates the sample, and dispenses urine onto each pad of the reagent strip. Color assessment of each reaction uses the same principle of reflectance as described previously. Timing remains consistent from sample to sample. The AUTION MAX is capable of assessing the color of a speci- men by using four wavelengths of light to obtain the tone (light, normal, dark) and hue of a urine specimen. Hues include colorless, blue, brown, green, orange, red, violet, yellow, and other. Light scatter is used to determine the turbidity of the specimen. Specific gravity is measured by assessing refractive index of LED-emitted light as it passes through the specimen. The AUTION MAX uses dual wavelength reflectance to measure the pH and chemical constituents of urine. Two wavelengths of light (except for hemoglobin) and three light reflection detectors are used.
An instrument in the iQ®200 series reads the specimen’s barcode, aspirates the sample, and performs urine sediment identification. The identification is done by enveloping a lamina of the sample with a suspension fluid that moves past the objective lens of the microscope. A digital camera, illumi- nated by a strobe lamp, captures 500 frames per sample. The Auto-Particle Recognition software uses size, shape, contrast, and texture to classify images. Digital images are reviewed by a technologist and correlated to chemical and physical findings prior to reporting. Electronic archiving of results allows results to be reviewed by multiple users for confirmation of results, quality control, or used in training sessions.
The combination of AUTION MAX and iQ®200 provides a fully automated urinalysis system. See Figure 15-1A for an image of the AUTION MAX and iQ®200 combination and Figure 15-1B for a close-up of the tube carrier as it passes the barcode reader. Some of Iris’ newer models, listed in Table 15-1, are available in the United States while others are currently available only in other global markets. Figures 15-2 through 15-5 show images of these newer models
SIEMENS MEDICAL SOLUTIONS DIAGNOSTICS
Siemens Medical Solutions Diagnostics manufactures the Clinitek® series of urine chemistry instruments. Both semiautomated instruments perform reagent strip analysis on a test-by-test basis, while the fully automated instrument is a load and walk away system. Figures 15-6 and 15-7 display the Clinitek®Status and Clinitek®Atlas.
SYSMEX
Sysmex UF-1000i Series instruments automate the analysis of urine sediment identification using “particle characteri- zation and identification based on detection of forward scatter, fluorescence and on adaptive cluster analysis.”2 Figure 15-8 displays an image of this instrument.
Particles are run through a flow cell utilizing a sheath reagent to ensure that they are in single file as they are
Figure 15-1. A. Iris Diagnostics Division iQ®200 Automated Urinalysis
System (AUTION plus iQ®200). B. Iris Diagnostics close-up of the
AUTION barcode reader and tube carrier
addressed by the laser light (see Fig. 15-9). Laser light scatters as it interrogates particles in the measuring zone and excites fluorochromes, which then emit light of different wavelengths. This fluorescent light is captured as electrical pulses by a photomultiplier as illustrated in Figure 15-10
Figure 15-2. Iris Diagnostics iChem®VelocityTM
Figure 15-3. Iris Diagnostics iQ®200ELITETM
Figure 15-4. Iris Diagnostics iQ®200SELECT
Figure 15-5. Iris Diagnostics iQ®200SPRINT
Figure 15-6. Siemens Medical Solutions Diagnostics manufactures the Clinitek® Status
Figure 15-7. Siemens Medical Solutions Diagnostics manufactures the Clinitek® Atlas.
Figure 15-8. Sysmex UF-100® Urine Cell Analyzer
Figure 15-9. Sysmex UF-100® Flow Cell Diagram.
Figure 15-10. Sysmex UF-100® Lateral Fluorescent Light System Dia-gram.
Measurements of fluorescence correspond to the inter- nal structures in the formed elements. As each particle flows through the measuring zone, a series of measure- ments is taken creating a fluorescence “fingerprint” by which the UF can recognize, classify, and count the cell. Automatic sample validation is available in addition to a user-definable flagging system for abnormal findings.
AUTOMATED BODY FLUID ANALYSIS SYSTEMS
Automated cell analysis instruments are also available to do cell counts and WBC differentials on spinal fluid samples. With these instruments, cells are first mixed with reagent fixative and then counted. Differentials counting enumerates numbers of neutrophils, lymphocytes, monocytes, and eosinophils. Automated cell counters use larger numbers of cells, enhancing precision and accuracy. Table 15-2 lists automated systems available for body fluid cell counting.
IRIS DIAGNOSTICS DIVISION
The Iris iQ® Body Fluid Module adapts the iQ®200 for identification and enumeration of cells in most body fluids including cerebrospinal, pleural, peritoneal, peritoneal lavage, peritoneal dialysate, pericardial, and general serous f luids. Automation of synovial f luid counts was approaching release for public knowledge at the time of this publication.
SYSMEX
The Sysmex XE-5000 Automated Hematology System (see Fig. 15-11) includes a body fluid–specific mode. This provides reportable WBC, RBC, and differential (polymor-phonuclear and mononuclear) counts for cerebrospinal, synovial, and serous body fluids. The XE-5000 analyzer uses fluorescent flow cytometry with hydrodynamic focusing technologies and a state-of-the-art diode laser bench to dif- ferentiate cell types in body fluid samples
Figure 15-11. Sysmex XE-5000 Automated Hematology System
Figure 15-12. SQA-V Sperm Analyzer
AUTOMATION OF URINE PREGNANCY
Special instruments have been developed that automate the interpretation of enzyme immunoassay tests. Once the test is set up and inserted into the reader, laboratory personnel can focus on other duties without worry of missing the read time. Quantitative human chorionic gonadotropin (HCG) is one such test that is interpreted by the VEDALAB Easy Reader.® Immunochromatographic rapid test cards are read by the meter using a high-resolution CCD camera. Integrated software analyzes the images and records the results.
REFERENCES
Lillian A. Mundt and Kristy Shanahan, Graff's Textbook of Urinalysis and Body Fluids, Second Edition 2011
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