羊水样本卵磷脂和鞘磷脂检测超高效液相色谱串联质谱方法的建立及应用

目的建立检测羊水中卵磷脂和鞘磷脂(L/S)的超高效液相色谱串联质谱(UPLC-MS/MS)方法,以便准确、高效地预测胎儿肺成熟度。方法收集孕32~39周孕妇分娩时的羊水样本23份。依据新生儿Apgar评分标准,有3例胎儿胎肺未成熟、20例胎儿胎肺成熟。另收集孕18周孕妇羊水样本7份作为基线对照,建立检测羊水中卵磷脂和鞘磷脂水平的UPLC-MS/MS方法,计算卵磷脂/鞘磷脂(L/S)比值,同时采用板层小体计数(LBC)法检测板层小体(LB),评价2种方法在预测胎肺成熟度中的价值。结果建立的检测羊水中卵磷脂和鞘磷脂的UPLC-MS/MS方法精密度良好,离子峰强度和保留时间均在可检测范围内,主成分分析(PCA)显示6个质控样本聚类良好。以L/S比值=10作为判断胎肺成熟度与不成熟的临界值,UPLC-MS/MS的敏感性和特异性均为100%。以LB=50×10^9/L作为判断胎肺成熟度与不成熟的临界值,LBC法的敏感性和特异性分别为80%和95%。结论建立了检测羊水中卵磷脂和鞘磷脂水平的UPLC-MS/MS方法,其结果可靠,可以准确、高效地预测胎肺成熟度。     

End of the line for fetal lung maturity testing

ObjectiveDuring the last decade, guidelines published by the American College of Obstetricians and Gynecologists (ACOG) and Society for Maternal Fetal Medicine (SMFM) have emphasized an increasingly limited role for fetal lung maturity (FLM) testing. As a reference laboratory for FLM testing, we were therefore interested in determining the impact of changing guidelines on our test volumes.MethodsWe retrospectively reviewed FLM test volume data from 2006 to 2016 for the following FLM assays: lecithin/sphingomyelin ratio, phosphatidylglycerol, disaturated lecithin, and lamellar body count.ResultsWe found that there was a precipitous decline in test volumes from 2006 to 2016; our analysis led us to discontinue providing reference laboratory FLM testing in 2016 given the very low volumes.ConclusionsThe 2019 ACOG guidelines now state that FLM testing no longer has clinical utility. Therefore, clinical laboratory directors should meet with obstetrics providers to discuss discontinuation of FLM testing at their institutions.     

Comparison of four automated hematology analyzers.

OBJECTIVE: To compare four automated hematology analyzers for efficiency and sensitivity. DESIGN: Four automated hematology analyzers were compared in a side by side study: Bayer ADVIA 120 (Bayer Diagnostic Division, Tarrytown, NY), Beckman Coulter GEN S (Beckman Coulter, Brea, CA), Abbott CELL DYN 3500 and CELL DYN 4000 (Abbott Diagnostics, Santa Clara, CA). 164 specimens were analyzed for cell counts, indices, and the automated WBC differential (DLC). Tallies were kept of all interventions, defined as any parameter necessitating examination of a stained blood smear by a clinical laboratory scientist. A 400-cell manual differential was performed on each specimen and used as the reference to prepare truth tables for each type of WBC. PATIENTS: Specimens comprised regular runs from this tertiary care teaching hospital. These included inpatients, outpatients, and oncology patients, including bone marrow transplant patients. MAIN OUTCOME MEASURES: Results from the truth tables were used for calculating sensitivity and efficiency for each analyzer. Each DLC parameter was analyzed for variance using the one-way ANOVA test. RESULTS: No intervention was required for 103 of 164 specimens for the CELL DYN 3500; the ADVIA gave 70 reportable DLCs without intervention, the GEN S provided 91 and the CELL DYN 4000 resulted in 117 of 164 DLCs without intervention. Agreement or efficiency was 65% for the CELL DYN 3500, 41% for the ADVLA, 58% for the GEN S, and 79% for the CELL DYN 4000. Sensitivity was 67% for the CELL DYN 3500, 86% for the ADVIA, 76% for the GEN S, and 71% for the CELL DYN 4000. Probability of significant variation was as follows for each parameter: % neutrophil 0.8747, % lymphocyte 0.8830, % monocyte 0.0296, % eosinophil 0.7903, and % basophil <.0001. CONCLUSION: The analyzers tested were acceptable for routine laboratory work. Selection would depend on individual need with respect to sensitivity and efficiency. The clinical significance of disagreement between the DLC and the manual differential remains to be determined.     

Aberrant lamellar body counts noted on the Beckman Coulter Unicel DxH 800

Abstract Background: The lamellar body count (LBC) plays a crucial role in fetal lung maturity testing. Lamellar bodies are often counted in the platelet channel of routine hematology analyzers, resulting in a rapid and inexpensive assay for fetal lung maturity. Recently, significant imprecision was noted during LBC validation on the Beckman Coulter Unicel DxH 800. Methods: The results of two Beckman Coulter Unicel DxH 800 instruments were compared to those of a Coulter LH 750 and Coulter LH 500. Three pools of amniotic fluid, commercial quality control materials, and proficiency test specimens were analyzed on all four instruments. Fifty patient specimens were also analyzed using the Coulter LH 500 and the Unicel DxH 800. Results: The mean values and precision obtained from commercial quality control materials and proficiency test samples were comparable on all four instruments. However, many erroneously low LBC results were produced from amniotic fluid pools using both DxH 800 instruments. The erroneous values were approximately 50% lower than respective target values, occurred randomly, and affected the low, medium, and high LBC results. Inter-assay precision of the three pools ranged from 24.7 to 39.0 CV% on the DxH 800 instruments. Conclusions: The source of LBC errors likely involves the exclusion of smaller lamellar bodies from the counts. The DxH 800 combines new data fusion technology and mathematical algorithms to produce increased accuracy and flagging efficiency. Laboratorians should be aware that the improved specificity of the DxH 800 may preclude its use for this laboratory-developed test.     

Clinical and laboratory trends in fetal lung maturity testing

BackgroundThe surfactant/albumin ratio is a popular fetal lung maturity (FLM) test that will be unavailable in the near future. We conducted surveys of obstetricians and clinical laboratorians to assess FLM testing trends from the perspectives of both disciplines and to identify how both communities might adapt to the loss of the surfactant/albumin ratio.Methods2067 physicians were surveyed about their familiarity with and clinical utility of various FLM tests. 6137 laboratorians were surveyed about their FLM test menu and volumes.ResultsTwenty-five percent of physicians indicated a decrease in FLM test ordering and the frequency of FLM testing has decreased significantly (p = 0.011) since 1998. The surfactant/albumin ratio is the most frequently offered FLM test and was the test of choice for 62% of physicians. Without the surfactant/albumin ratio, 68% of physicians would order the lecithin/sphingomyelin ratio and 44% would order the lamellar body count (LBC) which were offered by 18 and 13% of laboratories, respectively. 16% of laboratories were planning to offer the LBC within 24 months.ConclusionsFLM testing is decreasing. The loss of the surfactant/albumin ratio will increase the demand for the lecithin/sphingomyelin ratio and the LBC, yet few laboratories offer either test and most are not planning to offer the LBC.     

全自动血液分析仪对脑脊液细胞检查的应用分析

目的探讨Bayer ADVIA 120全自动血液分析仪（简称ADVIA 120）用于脑脊液（CSF）细胞检查的可行性和临床应用价值。方法采用ADVIA 120对取自111例患者的112份的脑脊液标本进行分析，并将结果与同期的手工镜检结果进行对比，计算相关系数。结果当标本中自细胞数〉95个／μL、红细胞数〈95个／μL时，2种方法结果有很好的相关性；ADVIA 120可以提供最可靠的CSF白细胞总数、淋巴细胞及中性粒细胞分类计数结果，但不能提供准确的单核细胞和嗜酸性粒细胞分类计数结果，本研究显示ADVIA 120不能区分异常病理细胞如肿瘤细胞等。结论ADVIA 120 CSF快速初步分析结果，可以作为临床上CSF检查的一种快速简便方法来满足临床的不同需要，但如要提供正确而全面的CSF细胞情况必须辅以手工镜检的结果。     

Analytical characterization of the Siemens Dimension EXL high-sensitivity cardiac troponin I assay

BackgroundSiemens Healthcare Diagnostics has four commercially available assays on different analytical platforms using different methodologies to generate signal. We assessed the analytical performance of the Dimension EXL hs-cTnI assay (LOCI method) across different matrices and compared it to two different acridinium ester-based hs-cTnI assays (ADVIA Centaur and Abbott ARCHITECT).MethodsThe analytical sensitivity and precision below the 99th-percentile was determined for the Dimension EXL hs-cTnI assay. Method comparisons were performed between the Dimension EXL contemporary cTnI and the hs-cTnI assays, between different matrices for the EXL hs-cTnI assay (serum, lithium heparin and EDTA plasma), and between different hs-cTnI assays (EXL versus ADVIA Centaur or Abbott ARCHITECT) using non-parametric analyses.ResultsThe limit of blank and detection were 0.9 ng/L and 1.7 ng/L, respectively, with imprecision of 5.8% at 8.6 ng/L and 3.2% at 47.5 ng/L. Comparison between the EXL contemporary cTnI and hs-cTnI assay (range: 2.6–4214 ng/L) yielded proportional lower concentrations for the hs-cTnI assay (slope = 0.86; 95%CI: 0.81 to 0.96, n = 40); however, there was no difference in concentrations below 100 ng/L between the assays (median difference = −2.7 ng/L; 95%CI: −9.8 to 9.3). Passing-Bablok regression analysis with EDTA plasma yielded proportionally higher concentrations with the EXL hs-cTnI versus Abbott hs-cTnI (slope = 1.45; 95%CI: 1.02–1.86, n = 40) with proportionally lower concentrations with EDTA versus lithium heparin plasma with the EXL hs-cTnI assay alone (slope = 0.93; 95%CI: 0.90 to 0.99, n = 40). Comparison with Abbott hs-cTnI concentrations below 100 ng/L in the three matrices, indicated that the EXL hs-cTnI assay yielded higher concentrations (median difference range: 3.4–9.4 ng/L), with differences also evident when comparing the EXL hs-cTnI assay to the ADVIA Centaur hs-cTnI assay.ConclusionThe Siemens EXL hs-cTnI assay meets the analytical criteria for a high-sensitivity assay, with assay specific cutoffs important to maximize clinical performance.     

Evaluation of a commercial immunoenzymometric assay for alpha-fetoprotein

A two-site immunoenzymometric assay (Abbott Diagnostics) for alpha-fetoprotein (AFP) in maternal serum and amniotic fluid has been evaluated for its suitability as a screening test for open neural tube defects. In a retrospective study based on 190 pregnancies of known outcome, performance of the kit in measuring both serum and amniotic fluid AFP correlated well with that of an in-house radioimmunoassay. Of 39 pregnancies associated with open neural tube defects, only four would not have been detected by the use of sequential measurement of serum and amniotic fluid AFP (also essentially in agreement with results obtained by the RIA). We conclude that this immunoassay could form the basis for a screening program for antenatal detection of open neural tube defects.     

Performance of a new hepatitis C assay on the Bayer ADVIA Centaur Immunoassay System

Bayer HealthCare LLC, Diagnostics Division has developed a new third-generation assay for the detection of antibodies to hepatitis C (anti-HCV) in human serum and plasma on the ADVIA Centaur immunoassay system. This assay employs magnetic particle separation technology with direct chemiluminescence for optimal assay performance. The assay is fully automated, requires a sample volume of 10 microl and has a throughput of up to 120 tests per hour. The ADVIA Centaur HCV2 Assay was tested with samples from HCV-infected individuals, blood donors, and hospitalized patients in an extensive performance evaluation at two sites in Europe in order to generate performance data in support of obtaining the Communautés Européennes (CE) mark for European market distribution. The HCV performance evaluation resulted in an overall diagnostic specificity of 99.9% and a diagnostic sensitivity of 100%. Assay performance evaluation, using HCV seroconversion performance panels, resulted in comparable or better results when compared to the comparison assay (Abbott AxSYM3 HCV Version 3.0 Assay). Data from the performance evaluation demonstrate that the ADVIA Centaur HCV Assay is a specific and sensitive automated immunoassay for detection of antibodies to hepatitis C virus with performance that is comparable to that of currently marketed assays. Additionally, this assay has the advantage of being on the ADVIA Centaur immunoassay system, which provides the flexibility of high throughput and full automation.     

Performance of a new HIV 1/O/2 assay on the Bayer ADVIA Centaur immunoassay system

Bayer HealthCare LLC, Diagnostics Division, has developed a new third-generation assay for the detection of antibodies to HIV 1, including group O, and HIV 2 in human serum and plasma on the ADVIA Centaur immunoassay system. The ADVIA Centaur HIV 1/O/22 Assay employs magnetic particle separation technology with direct chemiluminescence for optimal assay performance. The assay is fully automated, requires a sample volume of 50 microl and has a throughput of up to 120 tests per hour. The ADVIA Centaur HIV 1/O/2 Assay was tested in an extensive performance evaluation at two sites in Europe. Samples from HIV-1 and HIV-2 infected individuals, blood donors, hospitalized patients, and high-risk individuals were utilized to generate performance data in support of obtaining the Communautés Européennes (CE) mark for European market distribution. The comparison assay for the performance evaluation was the Abbott AxSYM HIV 1+2 gO Assay. The performance evaluation resulted in an overall diagnostic specificity of 99.9 % and a diagnostic sensitivity of 100%. Assay performance was further evaluated using HIV seroconversion panels. Equivalent results were obtained when the ADVIA Centaur HIV 1/O/2 Assay was compared to the comparison assay. The performance evaluation data demonstrate that the ADVIA Centaur HIV 1/O/2 Assay is a specific and sensitive automated immunoassay for detection of antibodies to HIV-1, including group O, and HIV-2 with performance that is comparable to that of currently marketed assays. Additionally, the ADVIA Centaur HIV 1/O/2 Assay has the advantage of being on an immunoassay system, which provides the flexibility of high throughput and full automation.     

The effect of auto-positive end-expiratory pressure on the arterial-end-tidal carbon dioxide pressure gradient and expired carbon dioxide slope in critically ill patients during total ventilatory support

To examine the effect of auto-positive end-expiratory pressure (autoPEEP) on the estimation of arterial carbon dioxide pressure (PaCO₂) from end-tidal carbon dioxide pressure (PetCO₂) during changes in minute ventilation (MV), we studied 24 consecutive sedated and paralyzed patients under controlled mechanical ventilation for acute respiratory failure. The patients were grouped according to whether they had autoPEEP: group I (n = 11) comprised non-autoPEEP patients and group II (n = 13) comprised autoPEEP patients. Patients were randomly ventilated at three different levels of MV: normal MV (basal tidal volume), high MV (tidal volume 2.5 mL/kg above basal), and low MV (tidal volume 2.5 mL/ kg below basal). Respiratory rate and inspiration to expiration ratio were kept constant during the study. In each condition, we measured arterial blood gases, expiratory capnograms, airway pressure, and autoPEEP. We determined PaCO₂-PetCO₂ gradient, predicted PaCo₂ (Pa'CO₂) [Pa'CO₂ = PetCO₂ for each condition + (PaCO₂ PetCO₂ gradient at normal MV)], and expired CO₂ slope. The PaCO₂-PetCO₂ gradient only remained stable in group I (mean values for low, normal, and high MV were 3.3, 3.3, and 3.5 mm Hg, respectively), while group II showed a significant difference during low MV (12.2 mm Hg) when compared with normal MV (8.4 mm Hg; P < .01) and high MV (8.9 mm Hg; P < .05). PaCO₂ and PetCO₂ showed significant correlations in both groups (r = .92 in group I and .79 in group II). However, Pa'CO₂ could only be safely estimated in patients without autoPEEP when the difference between PaCO₂ and Pa'CO₂, ranged between 1.6 and −1.9 mm Hg. Slopes of expired CO₂ greater than 3 mm Hg/s identified patients with autoPEEP of 89% sensitivity, 93% specificity, 94% positive predictive power, and 95% accuracy. A significant correlation was found between autoPEEP and expired CO₂ slope (r = .70; P < .001), between autoPEEP and PaCO₂-PetCO₂ gradient (r = .46; P < .001), and between CO₂ expired slope and PaCO₂ PetCO₂ gradient (r = .74; P < .001). These results indicate that in patients with acute respiratory failure under controlled mechanical ventilation, the presence of autoPEEP is associated with inaccuracy in the calculation of predicted PacoZ from PetcoZ after changes in MV at fixed respiratory rates.     

New developments in the standardization of total prostate-specific antigen

Objective: Analytical evaluation of the calibration of three recently launched assays for the measurement of total prostate-specific antigen, i.e., IMx Total PSA (Abbott), Elecsys PSA (Roche), and IMMULITE 3rd Generation PSA (DPC).

Design and methods: For accuracy assessment two reference materials were applied namely, Stanford 90:10 PSA Calibrator and Certified Reference Material 613 Prostate-Specific Antigen. Dilutions of these preparations were analyzed with all assays. In addition, clinical specimens from known prostate cancer or benign prostate hyperplasia patients and samples taken from an ongoing prostate cancer screening study were used for comparison.

Results: Application of the Stanford Calibrator revealed results well within 10% of the calculated values for all assays. Regarding the CRM Calibrator only the IMx Total PSA proved to approach the line of identity. The IMMULITE results differed about 40% and the Elecsys about 18% from the calculated values. The comparison with clinical specimens showed statistically different results for the combination IMMULITE-IMx and for IMMULITE-Elecsys. The regression lines for both collections were: y(IMx)=0.86×(IMMULITE)+0.12 (n = 104, r = 0.970, S_y/x = 0.883 μg/L) and y(Elecsys)=0.98×(IMMULITE)+0.38 (n = 97, r = 0.976, S_y/x = 0.733 μg/L). In the lower measuring range (PSA < 5.0 μg/L) as measured with the screening samples (n = 43), these differences were less pronounced.

Conclusion: In analytical sense a difference was found for both reference preparations in the assays studied. Clinically, despite improvements in methodology, results for total prostate-specific antigen are still not interchangeable. The possible consequences need to be elaborated.     

Amniotic fluid tests for fetal lung maturation--the good, the bad, and the promising.

OBJECTIVE. To assess promising laboratory tests for fetal lung maturity (FLM). DATA SOURCES. Professional literature. DATA EXTRACTION. Survey of literature. DATA SYNTHESIS. Traditional biochemical tests for FLM such as the LSR are reliable if performed properly but are difficult to perform, costly, and not widely available; most are not good predictors of respiratory distress syndrome. Many of the newer biochemical and biophysical FLM assays are more reliable, faster, require less personnel time, and are readily available. CONCLUSION. The development of laboratory tests to measure the presence or effects of pulmonary surfactant in amniotic fluid has contributed greatly to the management of premature deliveries; newer tests show promise but require more extensive evaluation.     

Lamellar body phospholipid content of amniotic fluid: a possible index of fetal lung maturity

Lamellar bodies, produced by secretory cells in the alveolar epithelium, are the major source of surfactant phospholipid. As the fetal lung matures, the membranous content of the lamellar bodies is secreted into the alveolar spaces and passes into the amniotic fluid, from which it can be isolated in a morphologically recognisable form. A method is described for the rapid isolation of a lamellar body fraction from amniotic fluid using a small air-driven clinical ultracentrifuge. The lamellar body phospholipid content of amniotic fluid increases towards the end of gestation, but the time of onset and the rate of this increase show wide individual variation. Preliminary results suggest that the lamellar body phospholipid content of amniotic fluid may be a useful index of fetal lung maturity.     

两种检测羊水板层小体方法评价及其临床应用

目的评价分别使用血细胞分析仪(MEK-8222K)和手工方法(显微镜镜检)计数羊水板层小体的临床应用价值。方法使用血细胞分析仪(MEK-8222K)计数101例孕妇(孕周为37周以上)羊水中的板层小体并与显微镜下计数的结果进行比较。结果仪器分析法和手工计数法的检测结果高度一致。结论仪器分析法是羊水板层小体计数的一种简单、快速、可靠的试验方法。     

Effect of albumin and lamellar bodies on fluorescence polarization of amniotic fluid

Using a probe and procedure developed for the Abbott TDx analyzer, we investigated the influence of albumin on fluorescence polarization of amniotic fluid. Polarization readings increased when albumin was added to either "mature" or "immature" amniotic fluids. Albumin added to a fraction rich in lamellar bodies (10,000 X g pellet) greatly increased polarization readings, but albumin added to the lamellar-body-free fraction resulted in only small increases. Adding increasing amounts of the lamellar-body-rich fraction from mature and immature pools to a constant amount of albumin decreased the polarization readings. We saw no correlation between amniotic fluid polarization and albumin concentration but found a significant correlation between polarization values and either total extractable phospholipids (r = 0.725, P less than 0.001) or the ratio albumin/total extractable phospholipids (r = 0.784, P less than 0.001). The concentration of albumin in amniotic fluid was variable and correlated poorly with gestational age.     

Characterization of amniotic fluid lamellar bodies by resistive-pulse counting: relationship to measures of fetal lung maturity

Resistive-pulse counting studies of amniotic fluid lamellar bodies are presented and demonstrate a strong concordance with the predictions of accepted measures of fetal lung maturity. Uncentrifuged as well as centrifuged specimens could be evaluated, because cells and debris are rejected electronically. The technique is not affected by bilirubin or debris of lysed whole blood, and only mildly by meconium. Lamellar body number density and mean lamellar body volume were determined for 161 uncentrifuged and 241 centrifuged specimens. Number density maturity criteria (40,000/microL and 26,000/microL, respectively) were shown to be highly concordant with established measures of fetal lung maturity; mean lamellar body volume did not extend this concordance. Since electronic cell counters are generally available 24 h per day and the approach requires neither centrifugation nor subjective interpretation and is rapid and inexpensive, it is proposed that determining lamellar body number density by resistive-pulse counting may be a useful initial screen for the assessment of fetal lung maturity.     

Measurement of "lamellar body phospholipid" in amniotic fluid as a method for assessing fetal lung maturity

A simple, rapid micro-method, suitable for use in a routine clinical laboratory, is described for isolating a surfactant fraction from 0.1 mL of human amniotic fluid and measuring its phospholipid content. We determined the phospholipid content of this fraction, referred to as "lamellar body phospholipid," in 451 samples of amniotic fluid collected within two days of delivery and related the data to the respiratory performance of the newborn in every case; 112 of the infants were delivered at 28-37 weeks gestation. The incidence of hyaline membrane disease was inversely related to the concentration of lamellar body phospholipid in the amniotic fluid. Eleven of 12 infants with lamellar body phospholipid values less than 25 mg/L and four of 44 infants with lamellar phospholipid values between 25 and 50 mg/L developed hyaline membrane disease or other serious respiratory problems possibly related to lung immaturity, whereas all of 395 infants with lamellar body phospholipid values of 50 mg/L or more were free from respiratory problems of this nature. The incidence of transient tachypnea was greatest when the lamellar body phospholipid value was between 25 and 50 mg/L, suggesting that this condition may be related to a degree of lung maturity.     

Improved fluorescence polarization assay for use in evaluating fetal lung maturity. III. Retrospective clinical evaluation and comparison with the lecithin/sphingomyelin ratio

We clinically evaluated, retrospectively, our improved fluorescence polarization assay for fetal lung maturity. The procedure requires 0.5 mL of amniotic fluid and a standard clinical laboratory fluorescence polarimeter (TDx Analyzer, Abbott Laboratories). We measured the L/S ratios for 93 freshly collected amniotic fluids, uncontaminated with blood or meconium, collected within three days of delivery. The fluids were stored frozen for eight to 32 months, then thawed and assayed for net fluorescence polarization. Fourteen of the infants developed respiratory distress syndrome; five, transient tachypnea of the newborn; and 74, no respiratory distress. The polarization assay and lecithin/sphingomyelin ratio had equivalent receiver operating characteristic curves, indicating no difference in their clinical performance. Although a prospective study with fresh amniotic fluid specimens will be necessary to establish a definitive reference range, the present study shows that this assay can be used to rapidly predict fetal lung maturity.     

Evaluation of low platelet counts by optical,impedance, and CD61‐immunoplatelet methods: estimation of possible inappropriate platelet transfusion

BACKGROUND: The Cell‐Dyn Sapphire (Abbott Diagnostics) detects platelets (PLTs) with a CD61 monoclonal antibody directed against glycoprotein IIIa as well as impedance (IMP) and optical (OPT) technology. We decided to evaluate low PLT counts produced by IMP and OPT methods and to compare them with the CD61 method. We also examined the possibility of inappropriate PLT transfusion resulting from an inaccurate PLT count. STUDY DESIGN AND METHODS: We analyzed consecutive blood samples with OPT PLT counts of less than 50 × 10⁹/L. We performed the PLT count with the OPT, IMP, and CD61 methods and we compared the number of prophylactic PLT transfusion indications according to the PLT counts determined by the OPT and IMP methods with the number of prophylactic PLT transfusion indications according to our reference CD61 method. RESULTS: We collected 135 samples. In the bias analysis, the OPT method and the IMP method showed higher PLT counts when compared with the CD61 method (mean of difference 1.69 × 10⁹ and 19.1 × 10⁹/L, respectively). We saw overtransfusion in 1.5% of cases and undertransfusion in 15.2% of cases (p = 0.01; McNemar's test) when we selected a threshold of 10 × 10⁹/L with the OPT method. We saw undertransfusion in 22.2% of cases (p = 0.03; McNemar's test) when we selected a threshold of 5 × 10⁹/L with the OPT method. CONCLUSIONS: Low PLT counts determined by the OPT and IMP methods showed some disagreement when compared with the CD61 method. This disagreement caused both PLT undertransfusion and overtransfusion.