Influence of first trimester biochemistry methodology on detection rate in screening for trisomy 21
Abstract
Objectives: The purpose of the study was to compare detection rates (DR) of FMF-certified and non-certified biochemical tests (BC) in trisomy 21 screening at 11–13 + 6 weeks.
Material and methods: In 2267 singleton pregnancies FMF-certified doctors measured crown to rump length (CRL) and nuchal translucency (NT). Serum samples were tested for free β-hCG and the PAPP-A using 2 analysers (Delfia — Perkin Elmer and Immulite 2000 — DPC), the results were expressed in MoM values and used for computer calculation of the risk for trisomy 21. The cut-off value for the high trisomy 21 risk was 1:300.
Results: Comparison of free β-hCG MoMs by DPC and Delfia demonstrated statistically significant differences in normal, and trisomy 21 fetuses respectively. Similarly, statistically significant differences were noted for PAPP-A MoMs. The above differences in MoMs resulted in altered sensitivity in screening for aneuploidy. The application of the FMF-certified method ensures a markedly higher DR = 74%, compared to non-certified tests (64%), both at 5% FPR. The ROC analysis was performed in order to assess the efficacy of both tests. Results of trisomy 21 BC + NT risk scales using the Delfia and DPC methods are highly significant (p < 0.0001), which means that their discrimination ability is > 90%. The difference between results obtained using the Delfia and DPC methods is AUC = 0.0150 and is statistically significant (Z = 2.4728, p = 0.0134).
Conclusions: The use of FMF-certified first trimester biochemistry analysers improves DR for trisomy 21. The use of non-certified analysers causes reduction of DR and an increase of invasive procedure rate.
Keywords: screening for chromosomal defects11 to 13 + 6 weeks scantrisomy 21first trimester biochemistryPAPP-Afree beta-hCG
References
- Nicolaides K. Screening for fetal aneuploidies at 11 to 13 weeks. Prenatal Diagnosis. 2011; 31(1): 7–15.
- Nicolaides KH. A model for a new pyramid of prenatal care based on the 11 to 13 weeks' assessment. Prenat Diagn. 2011; 31(1): 3–6.
- Kagan KO, Cicero S, Staboulidou I, et al. Fetal nasal bone in screening for trisomies 21, 18 and 13 and Turner syndrome at 11-13 weeks of gestation. Ultrasound Obstet Gynecol. 2009; 33(3): 259–264.
- Kagan KO, Valencia C, Livanos P, et al. Tricuspid regurgitation in screening for trisomies 21, 18 and 13 and Turner syndrome at 11+0 to 13+6 weeks of gestation. Ultrasound Obstet Gynecol. 2009; 33(1): 18–22.
- Wright D, Syngelaki A, Bradbury I, et al. First-trimester screening for trisomies 21, 18 and 13 by ultrasound and biochemical testing. Fetal Diagn Ther. 2014; 35(2): 118–126.
- Czuba B, Cnota W, Wloch A, et al. Frontomaxillary facial angle measurement in screening for trisomy 18 at 11 + 0 to 13 + 6 weeks of pregnancy: a double-centre study. Biomed Res Int. 2013; 2013: 168302.
- Noble PL, Abraha HD, Snijders RJ, et al. Screening for fetal trisomy 21 in the first trimester of pregnancy: maternal serum free beta-hCG and fetal nuchal translucency thickness. Ultrasound Obstet Gynecol. 1995; 6(6): 390–395.
- Spencer K, Souter V, Tul N, et al. A screening program for trisomy 21 at 10-14 weeks using fetal nuchal translucency, maternal serum free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A. Ultrasound Obstet Gynecol. 1999; 13(4): 231–237.
- Pietryga M, Borowski D, Czekierdowski A, et al. Polish Gynecological Society Ultrasound Section Guidelines on ultrasound screening in uncomplicated pregnancy. Ginekol Pol. 2012; 83(4): 309–315.
- Spencer K. First trimester maternal serum screening for Down's syndrome: an evaluation of the DPC Immulite 2000 free beta-hCG and pregnancy-associated plasma protein-A assays. Ann Clin Biochem. 2005; 42(Pt 1): 30–40.
