Automated Body Fluid Cell Counts

Body fluid cell count has been part of the hematology laboratory and remains a time-consuming manual task for technologists. The cell count test provides valuable information to clinicians in the diagnosis and treatment of a various medical conditions. Albeit the diagnostic prowess of cell counts, there has also been an intrapersonnel variation in counts that proves the lack of precision among testing personnel. As laboratory professionals, we are trained that precision is important in the performance of cell counting procedures; therefore the implementation of automated body fluid counts will improve these quality parameters.

Automated methods for body fluid cell counts have been rapidly replacing manual hemacytometer methods. Advances in medical technology, especially in hematology instrumentation, have decreased the turnaround times and improved precision counts for body fluids. Technological advances in hardware and software engineering have developed instruments with expanded analytical capabilities that enable processing multiple specimen types including urine, CSF, peritoneal fluid, pleural fluid, synovial fluid, and lavages on a single analyzer.1 Most body fluid instruments like the Sysmex XE-5000 have analyzed body fluids easily and quickly. In a study published in Lab Medicine, the Sysmex XE5000 technology showed significant improvement in the ability of automated hematology analyzers regarding body fluid analysis.2 This technology provides counting nucleated cells in an acellular fluid(i.e. Cerebrospinal fluid). This technology also offers differential capabilities between mononuclear and polymorphonuclear cells, providing laboratory technologists and clinicians rapid, cellular differential analysis.

Laboratory technologists should not fear that their jobs will be replaced by these instruments. In fact, laboratory professionals should be enthused that it provides ease in their work, improves quality, decreases work load, and increases efficiency in their processes. The limitations that need to be considered in automated cell counts analyzers are the use of purulent specimens where the main concern is clogging the instrument’s flow cell apertures. Crystals in synovial fluids may cause a false increase in counts; in these cases, manual intervention in cell count may be warranted. Extremely clear fluids with low cell counts also limit the application of automated methods and may warrant manual analysis. Of important consideration as well is the microscopic review of cellular distribution when malignancy is of diagnostic consideration.

Modernization of laboratory equipment and analysis provide ease in operation from a management stand point but also efficiency, accuracy and precision in reporting of results. Automation of body fluid counts provides help to technologists and a rapid diagnosis tool for clinicians.

 

Reference

 

  1. Scott, G. (2014, June 9). An automated approach to body fluid analysis. Medical Laboratory Observer.

Williams, J., MD. (2011). Gaining Efficiency in the Laboratory – Automated Body Fluid Cell Counts: Evaluation of the Body Fluid Application on the Sysmex XE-5000 Hematology Analyzer . Lab Medicine, 42(7).

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Carlo Ledesma, MS, SH(ASCP)CM MT(ASCPi) MT(AMT) is the program director for the Medical Laboratory Technology and Phlebotomy at Rose State College in Midwest City, Oklahoma as well as a technical consultant for Royal Laboratory Services. Carlo has worked in several areas of the laboratory including microbiology and hematology before becoming a laboratory manager and program director.

Body Fluid Testing

When I started my career in laboratory medicine, we tested any fluid that was handed to us, for any analyte requested by the doctor.    We did this for a number of reasons that we thought were good ones including that the doctor is a medical professional who knows what he wants and needs, and that the test results will help diagnose and treat the patient. We were trying to be helpful.  Along the way though, laboratory professionals have come to understand that testing like this may not provide accurate results and may be doing more harm than good.

Now days, CLIA has clearly mandated that if the manufacturer of an FDA-approved assay system has not validated that system for a specific fluid type, the lab must perform that validation before testing and reporting results on that fluid type.

This is sometimes a hard rule to explain to the medical staff who have been trained in medical school to order such things as amylase on peritoneal fluid to look for pancreatic injury, or glucose on nasal fluid drainage when a CSF leak is suspected.  And these doctors often have literature references for what they wish to have measured, although in general the references are not recent.  I have a three-pronged approach to the explanation I give doctors as to why I won’t analyze the sample they sent me.

First, and probably most importantly, I cannot guarantee the accuracy of the result.   Matrix effects are real and a test designed for serum will not perform the same on urine.  Similarly, a test designed for serum and urine will not perform the same on a pharmacy preparation or an ascitic fluid sample.  The result I provide if I test that sample could very well be wrong.

Secondly, I have no way to interpret the results of the test on an un-validated fluid type.  There are no established reference intervals that allow us to determine the meaning of the result we’re providing.  For example, who knows how much glucose is normally present in nasal drainage?  I would assume no one knows, because why would you measure it in normal nasal drainage, and for that matter, what constitutes normal nasal drainage?  Thus if I test that unknown sample for the analyte requested, I’m providing a possibly inaccurate result that is uninterpretable.  And the physician is going to treat the patient on the basis of that result.  In most cases, the physician changes his or her mind at this point in the discussion.

However, if that isn’t enough, I bring out the big guns.  The agencies under which the lab operates forbid me from analyzing this sample for this analyte unless I validate the sample fluid type in my lab using the stringent validation criteria described in CLIA.   This validation would take a considerable amount of time and resources and enough patient samples to set a reference interval.

If a doctor would still like to be able to order that test on that sample type after the discussion, I request that the doctor be involved in the validation process.  First of all, I will want to know that enough of these tests will subsequently be ordered that the time and effort spent to validate the test will be worth it.   In addition, the doctor will need to collect sufficient numbers of that sample type to allow us to perform an adequate validation and reference interval study.  Also, QC material with the same matrix as the fluid type will need to be used and may have to be made in-house as it’s generally not commercially available.  Biannual proficiency testing for that fluid type will need to be performed also, with internal PT developed for it.   All of these considerations mean that the number of body fluid types and analytes we have validated is small, but we do not analyze un-validated fluid types.  We will often try to locate a reference lab who does analyze them for a doctor.  When that fails we will try to help the doctor find an answer to his medical question through use of other, legitimate tests.

-Patti Jones PhD, DABCC, FACB, is the Clinical Director of the Chemistry and Metabolic Disease Laboratories at Children’s Medical Center in Dallas, TX and a Professor of Pathology at University of Texas Southwestern Medical Center in Dallas.