title: Fifteen years of triple tests in The Netherlands; the life cycle of a screening test.
abstract: OBJECTIVE
  This report provides an overview of 15 years prenatal screening for Down syndrome (DS).
  
  
  METHODS
  Between 1991 and 2005, blood samples for the triple test were sent for analysis to our laboratory. Test results were considered screen-positive for neural tube defects (NTDs) if the serum alpha-1-fetoprotein > or = 2.50 MoM for singleton pregnancies or screen-positive for DS if the calculated risk was at least 1 in 250.
  
  
  RESULTS
  As many as 42 554 tests were performed. Data on the pregnancy outcome were available for 30 290 screening tests (71.2%). In 1991, most requests (93%) came from the university hospitals; thereafter a shift toward midwives occurred. Until 2001, the number of requests rose to 3500 a year. Most samples were collected between 15 and 17 weeks of gestation. The median age of women for whom a test was requested increased from 30.5 to 34.5. The detection rate (DR) for DS remained stable over the years (80%), with a false positive rate of about 13%. The DR for Trisomy 13, 18, and NTD was 50, 68, and 70%, respectively.
  
  
  CONCLUSIONS
  Based on the results of this study, the triple test may be considered a fairly good second trimester screening test. Here it is shown that health practitioners got more acquainted with the test through the years. This may have served the swift introduction of a formal national screening program that started in January 2007.
authors.affiliation: Department of Obstetrics, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Lundlaan 6, Utrecht, The Netherlands. E.Wortelboer@umcutrecht.nl
authors.forename: E J
authors.initials: EJ
authors.lastname: Wortelboer
authors.forename: M P H
authors.initials: MP
authors.lastname: Koster
authors.forename: Ph
authors.initials: P
authors.lastname: Stoutenbeek
authors.forename: J G
authors.initials: JG
authors.lastname: Loeber
authors.forename: G H A
authors.initials: GH
authors.lastname: Visser
authors.forename: P C J I
authors.initials: PC
authors.lastname: Schielen
mesh_terms: D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008403:Mass Screening / Q000379:methods / Q000639:trends*; D009426:Netherlands; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis / Q000379:methods / Q000639:trends*; D012306:Risk