Evaluation of a Dried Blood Spot Assay to Measure Prenatal Screening Markers Pregnancy-Associated Plasma Protein A and Free -Subunit of Human Chorionic Gonadotropin (original) (raw)
Prenatal Diagnosis, 2011
To determine the stability of first trimester free-β human chorionic gonadotrophin (free-β hCG) and pregnancy-associated plasma protein-A (PAPP-A) in dried blood spots (DBSs) under typical storage conditions. Methods First trimester maternal blood was spotted onto filter paper and left to dry. DBSs were analysed for PAPP-A and free-β hCG using an AutoDELFIA dual assay at t = 0. Cards were stored at one of -20 • C, refrigerator temperature, room temperature or 30 • C and reanalysed at set future time points. Free-β hCG was stable (<10% change in concentration) under all temperatures tested for at least 35 days. PAPP-A was stable at -20 • C and refrigerator temperature for at least 35 days. However, PAPP-A levels decreased by 10% at 4.1 days at room temperature and at 3.9 days at 30 • C. Longer-term storage at -20 • C and refrigerator temperature showed that both PAPP-A and free-β hCG levels were significantly decreased by 107 and 244 days. Conclusions Free-β hCG stability is greatly improved in DBS compared to serum storage; however PAPP-A stability is decreased in the DBS medium. Despite this DBS, screening may not necessitate such strict storage and transportation rules compared to serum screening programmes.
Archives of Gynecology and Obstetrics, 2012
Non-invasive Wrst trimester screening for fetal aneuploidy is based on the consideration of fetal nuchal translucency, biochemical serum markers 'pregnancy associated plasma protein A' (PAPP-A), and 'free beta-humane chorionic gonadotropin' (f -hCG). The blood sera of 168 pregnant women in 11 + 0 to 13 + 6 weeks of gestation were examined by both the COBAS (Roche Holding GmbH, Germany) and KRYPTOR (Brahms GmbH, Germany) immunoassay systems in two quality controlled laboratories. The concentration values were converted into multiple of median (MoM) values and compared through a two-tailed t test. The concentration values of PAPP-A diVered signiWcantly from each other (p < 0.0001). COBAS produced on average 0.09 MoM higher values in comparison to KRYPTOR (CI 95% = 0.06-0.11 MoM). In contrast, the concentration values of f -hCG did not diVer signiWcantly (p value = 0.20). The values produced by COBAS were on average only 0.02 MoM higher in comparison to KRYPTOR (CI 95% = ¡0.01 to 0.05 MoM). Which of the two systems generates the more precise results should be evaluated in a large-scale prospective study with the pregnancy outcomes.
Background: Although dried blood spots (DBS) are very convenient for massive screening, there are very few examples of their application in maternal serum screening of Down's syndrome and neural tube defects. For large-scale mass population screening in Brazil, a continental country, DBS would be fairly recommended. As there are no easily available commercial assays of AFP and hCG in DBS, the Wallac Delfia fluoroimmunometric assays intended for these biochemical markers were adapted to DBS. Methods: Serum specimens and DBS obtained from 116 pregnant women were analyzed by conventional methodology and by the adapted assays, respectively. Precision (within-run and between-run), recovery and detection limits studies were conducted Results: The non-linear regression fit of the levels of AFP and hCG in DBS by gestational age in days was described. There was a strong statistically significant correlation between the levels of these analytes in serum specimens and in DBS. For both analytes, the precision variances were compared to those presented by the manufacturer for serum samples. Conclusion: It is feasible to use these DBS adapted assays in maternal serum screening programs.
A historical and practical review of first trimester aneuploidy screening
Seminars in Fetal and Neonatal Medicine, 2014
There have been tremendous advancements over the past three decades in prenatal screening for aneuploidy and we have changed our practice from screening by maternal age alone to 'combined' first trimester screening and circulating cell-free fetal DNA. We currently use the nuchal translucency and biochemical markers of free β-hCG and PAPP-A to determine the risk of fetal aneuploidy. The primary goal is to identify higher risk women for fetal aneuploidy early in pregnancy and give them the option to pursue invasive testing in a timely manner if desired.
BJOG : an international journal of obstetrics and gynaecology, 2012
Please cite this paper as: Savvidou M, Syngelaki A, Muhaisen M, Emelyanenko E, Nicolaides K. First trimester maternal serum free β-human chorionic gonadotropin and pregnancy-associated plasma protein A in pregnancies complicated by diabetes mellitus. BJOG 2012;119:410–416.Objective To investigate whether markers of first trimester screening for aneuploidies, including fetal nuchal translucency (NT), maternal serum free β-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein A (PAPP-A), are altered in women with pre-existing type-1 and type-2 diabetes mellitus, and in women that subsequently develop gestational diabetes mellitus (GDM).Design Retrospective analysis of prospective combined screening for aneuploidies in singleton pregnancies at 11+0–13+6 weeks of gestation.Setting Antenatal clinic.Population Singleton pregnancies at 11+0–13+6 weeks of gestation resulting in the delivery of phenotypically normal neonates. The study included 194 women with type-1 diabetes, 122 women with type-2 diabetes, 779 women who developed GDM and 41 007 non-diabetic controls.Methods Maternal free β-hCG and PAPP-A levels were expressed as multiples of the respective normal median (MoM), and fetal NT was expressed as a difference from the expected median (Δ).Main outcome measures Comparison of median MoM maternal free β-hCG and PAPP-A, and fetal NT, in the four outcome groups.Results There were no significant differences between the groups in median ΔNT and maternal free β-hCG MoM. Maternal median PAPP-A in type-2 diabetes, compared with the non-diabetic group, was reduced (0.75 MoM, IQR 0.50–1.09 MoM versus 1.00 MoM, IQR 0.68–1.42 MoM; P < 0.001), which resulted in doubling in the false-positive rate in the combined screening in this population. There were no significant differences in maternal PAPP-A between the other groups.Conclusions In women with type-2 diabetes, the estimation of accurate patient-specific risk in the first trimester combined screening for aneuploidies necessitates an adjustment of maternal serum PAPP-A.