title: Nasal bone in screening for T21 at 11-13 + 6 weeks of gestation - a multicenter study.
abstract: Trisomy 21 is one of the most common chromosomal defects diagnosed prenatally. Screening for Down syndrome is based on maternal age, measurement of crown-rump length, nuchal translucency and fetal heart rate, together with free β-hCG and PAPP-A at 11 to 13 + 6 weeks. Introduction of additional ultrasound marker of trisomy 21 (evaluation of the nasal bone) may result in increased DR and decreased invasive diagnostic testing rates (FPR).
  
  
  
  Ultrasound scan with NB evaluation was performed in 5814 fetuses during routine screening for chromosomal defects at 11 to 13 + 6 weeks of gestation. DR and FPR coefficients were calculated for 4 levels of risk as cut-off points for screening model 1, based on MA, NT, and first trimester biochemistry, as well as for screening model 2, based on MA, NT, first trimester biochemistry and NB.
  
  
  
  There were 5708 normal cases, 71 cases of trisomy 21 and 35 cases of other chromosomal defects. NB was absent in 46 (64.8%) cases and present in 25 (35.3%) cases of trisomy 21, comparing to present NB in 5463 (95.7%) and absent in 245 (4.3%) of normal cases.
  
  
  
  First-semester screening with additional NB assessment significantly increases the detection rate for trisomy 21 and decreases the rate of false-positive results. Adding NB evaluation at the risk level of 1:50 causes only a small increase in detection rate. Invasive procedures should be performed in that group regardless NB assessment.
authors.affiliation: Department of Obstetrics and Perinatology, Medical University of Warsaw, Poland. piotr.wegrzyn@wum.edu.pl.
authors.forename: Piotr
authors.initials: P
authors.lastname: Węgrzyn
authors.forename: Bartosz
authors.initials: B
authors.lastname: Czuba
authors.forename: Dawid
authors.initials: D
authors.lastname: Serafin
authors.forename: Wojciech
authors.initials: W
authors.lastname: Cnota
authors.forename: Mariusz
authors.initials: M
authors.lastname: Dubiel
authors.forename: Marek
authors.initials: M
authors.lastname: Mączka
authors.forename: Dariusz
authors.initials: D
authors.lastname: Zarotyński
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Ruci
authors.forename: Mirosław
authors.initials: M
authors.lastname: Wielgoś
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Sodowski
authors.forename: Dariusz
authors.initials: D
authors.lastname: Borowski
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000453:epidemiology; D005260:Female; D006801:Humans; D009295:Nasal Bone / Q000002:abnormalities* / Q000000981:diagnostic imaging; D048208:Nuchal Translucency Measurement / Q000379:methods; D011044:Poland / Q000453:epidemiology; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human
keywords: chromosomal defects; nasal bone; screening for trisomy 21