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Reliable laboratory methods for detecting congenital CMV infection are valuable since CMV infections are asymptomatic and because early detection is important for correct management and counseling of expectant mothers.Compare the Beckman Coulter Access(®) method for the Unicel(®) DxI 800 analyzer with the bioMérieux VIDAS(®) method for two serological markers: CMV IgG and CMV IgM.Precision was determined with CLSI EP5-A2 protocol. Linearity of the Access CMV IgG was evaluated using selected high positive samples. Performance was assessed by testing non-selected pregnant women, frozen negative and positive samples with recent and old infections. Kinetics of the anti-CMV antibodies response was studied using samples from pregnant women with a recent infection. In a prospective study, 3992 pregnant women were screened for determining prevalence of a primo-infection and CMV IgM non-specific rate.Total CV is lower than 10% and 12% for Access CMV IgG and CMV IgM. The IgG method is linear (R(2)=0.999) with recoveries between 85% and 108%. Correlation between Access and VIDAS CMV IgG is highly significant (P0.001). Observed agreement was 97.4% for CMV IgG and 93.7% for CMV IgM. Relative sensitivity and specificity was 97.2% and 100% for IgG and 100% and 97.4% for IgM. Kinetics of the antibody response measured with Access methods is significantly higher (P0.02) when compared with VIDAS and probably easier to interpret. Prevalence of a recent infection was 0.85% and CMV IgM non-specific rate was 2.9%.Good sensitivity and specificity and pronounced anti-CMV antibody response make the Access CMV IgG and IgM tests suitable for screening prenatal CMV infections.

Summary Objective: Choice of parameter sets used to calculate Down's syndrome risks is complicated. Published population statistics were compared with assay-specific parameters to optimise screening efficiency. Design: Weight-corrected Gaussian population statistics for α-fetoprotein (AFP), human chorionic gonadotropin (HCG) and unconjugated oestriol (uE3), expressed as log10 multiples of median (MoM) were established for a Belgian cohort of 748 unaffected pregnancies. Using Cuckle's method and Access®-specific data, Down's syndrome parameters were tailored to the Belgian cohort. Correlated marker triplets for affected and unaffected pregnancies were modelled and combined with maternal age to calculate term risks for Trisomy 21. Receiver-Operator-Curve (ROC) analysis was performed to identify the optimally-performing population set. Results: Log-normal distributions for the Access® markers had geometric mean MoM values close to zero and standard deviation values equal to 0.1460 (AFP), 0.2185 (HCG) and 0.1317 (uE3). Correlation between AFP and other markers was significant (p

Objectives: To establish gestational age-specific mid-trimester normal medians for the prenatal serum markers α fetoprotein (AFP), human chorionic gonadotropin (HCG) and unconjugated oestriol (uE3) for a Belgian population by using the Beckman Coulter Access chemiluminiscent immunoassays; to compare these data with data obtained from other geographical regions; to propose regression coefficients for regressed medians and analyse variation induced by different regression equations; to evaluate the effect of formulas used for gestation correction on estimating risk in Down’s syndrome. Design: Data derived from 862 fresh serum samples from women being screened for Down’s syndrome pregnancy, composed of selected pregnancies deemed to be normal, were examined in a retrospective study. Regressed medians were calculated by using a first-degree logarithmic–linear fit of the raw data. Multiples-of-median (MoM) values estimated by using a simple logarithmic–linear equation were compared with those calculated with higher-degree polynomials chosen with a goodness-of-fit analysis. Model-specific variation was estimated and the effect on risk for Down’s syndrome was evaluated. Results: Regressed medians (Y) for Access serum markers AFP (IU/ml), HCG (IU/ml) and uE3 (nmol/l) for a Belgian population can be estimated with the equation Y = 10(A+BX) with X = decimal weeks. The best fit was obtained with a third-degree and a second-degree polynomial for AFP and uE3, respectively. Differences between the medians and among the slopes of the geographical populations were found to be significant (analysis of covariance, p Conclusions: Belgian marker medians versus gestational time are found to show a pattern that is similar to that in the literature. The log–linear equation is observed to give a good fit and can be suggested as a tool for calculating median MoM values for Belgian laboratories that use Access biochemical prenatal markers.

Background This report describes a nephelometric assay for measuring complement 3d (C3d). Methods C3d was separated from C3 and the other C3 split products by polyethylene glycol precipitation. The supernatant containing C3d was then measured by rate nephelometry in a Beckman Immage rate nephelometer using a specific antibody. Calibration was performed with dilutions of a standard, which was obtained by incubating a serum pool at 37°C for 7 days. This incubation step allowed the activation and breakdown of C3 into C3d. Results The assay was linear across the normal and pathological range. Precision studies showed within-run and between-run coefficients of variation of < 5% and < 6%, respectively. The nephelometric results are comparable with those obtained by radial immunodiffusion. Neither haemoglobin nor lipids interfere with the assay.

Serum creatinine is important for detecting the beginning of a decline in kidney function. The Beckman Coulter Jaffe reagents for measuring creatinine have been standardized to the internationally accepted reference method: isotope dilution mass spectrometry (IDMS). The impact of this recalibration on the Beckman CoulterRecalibrated Jaffe (calibrator set points IDMS traceable) and classic National Institute of Standards and Technology (NIST) creatinine methods (traceable to NIST 914a) were compared with an enzymatic method (Sentinel, traceable to NIST SRM 967). All measurements were performed on Synchron DxC 800 systems. Imprecision of the routine methods was studied using the Clinical and Laboratory Standards Institute (CLSI) protocols and laboratory quality survey. Thirteen plasma pools, with concentrations After recalibration of the Jaffe method, median bias (μmol/L) decreased from 12.4 (95% CI: 9.1–21.2) to 7.3 (95% CI: 1.5–10.5). Imprecision of the Jaffe method is in agreement with the claim of the manufacturer, namely Recalibration significantly reduced bias of the Jaffe method. For pediatric samples, recalibrated Jaffe results do not comply with either the imprecision goal or the total error based on biological variability. Adult recalibrated Jaffe results are in compliance with the goals based on biological variability and with the acceptance criteria from the NKDEP.

Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published population data is optimal. Screening efficiency realized with measurement procedure-specific population parameters is compared with selected population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p

Adjusting maternal serum markers for maternal weight is considered to be a standard practice when screening for pregnancies associated with Down's syndrome. The choice of model for taking maternal weight into account is, however, rarely explicitly evaluated.The relationship between the maternal serum markers alphafetoprotein (AFP), human chorionic gonadotropin (HCG) and unconjugated oestriol (uE3), determined with the Beckman Coulter access reagents and maternal weight was investigated in a cohort of 752 Belgian women being screened for pregnancy associated with Down's syndrome. Two different models (the log-linear equation and the linear-reciprocal equation) were used to determine the relationship between the serum markers and maternal weight.A significant relationship between log(10) multiples of median (MoM) values and weight (kg) was obtained for all markers, and the log-linear model had higher coefficients of determination (r(2)) when compared with the linear-reciprocal model. Weight correction with either method achieved the optimum effect that the correction factor for a woman with a population median weight of 65.5 kg was not significantly different from 1. Simulated weight-corrected MoM values with the two approaches were compared and variation was estimated. The mean difference between the weight-corrected MoM values calculated by the two methods was 7.8% (SD 4.3%) for AFP, 14.0% (4.4%) for HCG and 5.9% (3.2%) for uE3. This resulted in a difference in risk estimate of 1.66-5.34% for Down's syndrome owing to weight correction algorithm differences in women of median weight.The log-linear weight correction approach was shown to be marginally more effective by a goodness-of-fit analysis. Differences in weight-corrected MoM values estimated with the two approaches are highly significant (p0.0001, Wilcoxon's paired sample test), but the effect on risk calculation was not significant. It was observed that the changes in risk became significant the more the MoM correction factors deviated from 1.