Quality control in hematology
A quality control (QC) protocol for hematology, as for other sections of the laboratory, should encompass both internal and external QC programs. The extent to which a hematology laboratory should be involved depends upon various factors, including availability of facilities, financial resources, range of tests, workload, the number of staff and their levels of training, and the overall organization of the laboratory. To ensure quality patient care, the intralaboratory QC program must include at least the minimal measures of monitoring and control at each step from collection of blood specimens, through the actual processing and analysis, to reporting of the results. The protocol should be written concisely and in simple language; the procedure manual should offer all of the pertinent information along with references; all concerned personnel should be well trained and competent; and adequate facilities and time should be available for the purpose of QC. Continuing education is also an integral part of an effective QC program. Three very important aspects of QC in hematology are calibration of automated instruments, monitoring of accuracy and precision of instruments and procedures, and verifying the reliability of test results. In the absence of a true primary reference/standard for calibration of instruments for the CBC, the most commonly performed hematologic test, the use of commercial calibrators is acceptable. A combination of commercial controls (three levels) and retained or fresh patient blood specimens is recommended for monitoring of accuracy and precision on a long- and short-term basis. Patient red-cell indices moving average data allow continuous monitoring of instrument performance and should be used as an adjunct to other QC approaches to detecting instrument calibration drift. Correlation of results of related parameters and careful review of blood films remain the two most important and widely used approaches to ensure reliability of results obtained from automated hematology instruments. Participation in an external QC program offers the most practical means of monitoring overall work performance in comparison with instrument, method, and/or reagent-based peer group data. A laboratory may choose to participate in one or more national and/or regional QC programs, depending upon the range of tests it performs and the requirements of accreditation and regulatory agencies. Most of the accreditation agencies require participation in programs covering at least all of the routinely or frequently performed tests and, if available, also in those for infrequently performed tests.(ABSTRACT TRUNCATED AT 400 WORDS)
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- "For example, it has been speculated that 'milking' the finger to stimulate blood flow after the finger prick can result in more plasma being pushed onto the microcuvette, causing a dilution effect on Hb concentration  . However, it is important to note that we took extensive efforts to adequately train and test our field staff on proper HemoCue® testing procedures using standardized techniques  and quality controls  . Therefore, we believe this highlights the concern of using this method even among highly qualified and trained field staff. "
ABSTRACT: Genetic hemoglobin (Hb) E variants are common in Cambodia and result in an altered and unstable Hb molecule. We evaluated two methods to measure Hb concentration among individuals with and without Hb variants using a hemoglobinometer (HemoCue®) and a hematology analyzer (Sysmex XT-1800i). We determined the bias and concordance between the methods among 420 Cambodian women (18-45 y). Bias and concordance appeared similar between methods among women with no Hb disorders (n=195, bias=2.5, ρc=0.68), women with Hb E variants (n=133, bias=2.5, ρc=0.78), and women with other Hb variants (n=92, bias=2.7, ρc=0.73). The overall bias was 2.6g/L, resulting in a difference in anemia prevalence of 11.5% (41% using HemoCue® and 29.5% using Sysmex, p <0.001). Based on visual interpretation of the concordance plots, the HemoCue® device appears to underestimate Hb concentrations at lower Hb concentrations and to overestimate Hb concentrations at higher Hb concentrations (in comparison to the Sysmex analyzer). Bias and concordance were similar across groups, suggesting the two methods of Hb measurement were comparable. We caution field staff, researchers and policy makers in the interpretation of data and the impact that bias between methods can have on anemia prevalence rates. Copyright © 2014 Elsevier B.V. All rights reserved.
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ABSTRACT: The pre-analytic, analytic, and post-analytic stages of laboratory testing present challenges to the attainment of accurate and timely information. These include sampling errors, quality control, and interpretation of results. Learning about the benefits and limitations of specific tests allows the physician to use the laboratory more productively and cost-effectively.
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ABSTRACT: A study lasting for 18 months using interlaboratory surveys was carried out to assess the analytical quality of Jordanian haematology laboratories that represent one of the developing countries. The study surveyed 50 laboratories constituting the majority of clinical laboratories in the central region of Jordan using 15 control specimens of whole fresh blood and eight freshly prepared blood smears. The study covered the routine haematological parameters of PCV, Hb, RBC, WBC and differential white blood cell count. More than 97% of Jordanian laboratories using cell counters achieved the medically useful criteria for analytical performance, this figure was reduced to 84% in laboratories using manual methods. Jordanian laboratories, however, were far from achieving the analytical goals that have been proposed based on intraindividual biological variation. This study stressed the need for a national EQA scheme in haematology, to reach a common level of standardization.
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