title: Performance of first-trimester combined screening for trisomy 13 and 18 with the double test taken at a gestational age of 8 + 0 to 13 + 6.
abstract: OBJECTIVE
  To evaluate the performance of the combined test for first-trimester screening for trisomy 18 and 13, when the double test is scheduled weeks before the nuchal translucency scanning.
  
  
  METHODS
  The study included all 40 cases of trisomy 18 and 13 from April 2004 to October 2008 in a screening programme, where the double test was measured in gestational weeks 8 + 0 to 13 + 6 and the nuchal translucency in weeks 11 + 2 to 13 + 6.
  
  
  RESULTS
  Twenty-eight among the 40 cases had complete information on all variables in the first-trimester screening test. Among 19 cases having the double test taken before 10 + 0 weeks, 10 cases were detected (detection rate (DR) = 53%) and among 9 cases having the double test taken after 10 + 0 weeks, 6 cases were detected (DR 67%). There was no significant difference in the DRs (p = 0.48). A total of 29 cases were detected at the first-trimester screening, resulting in an overall DR for trisomy 18 and 13 at 73%.
  
  
  CONCLUSIONS
  This study showed no significant differences in the trisomy 18/13 DRs when grouped according to having the double test taken before or after 10 + 0 weeks. The DR was 73% at the first-trimester screening.
authors.affiliation: Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby, Aarhus, Denmark. ida.kirkegaard@ki.au.dk
authors.forename: Ida
authors.initials: I
authors.lastname: Kirkegaard
authors.forename: Olav Bjørn
authors.initials: OB
authors.lastname: Petersen
authors.forename: Niels
authors.initials: N
authors.lastname: Uldbjerg
authors.forename: Niels
authors.initials: N
authors.lastname: Tørring
mesh_terms: D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D002882:Chromosomes, Human, Pair 13; D002887:Chromosomes, Human, Pair 18; D005260:Female; D005865:Gestational Age; D006801:Humans; D008875:Middle Aged; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000235:genetics*; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D012189:Retrospective Studies; D014314:Trisomy / Q000175:diagnosis* / Q000235:genetics
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A