title: Prospective assessment of the Hong Kong Hospital Authority universal Down syndrome screening programme.
abstract: OBJECTIVE
  To evaluate the performance of the locally developed universal Down syndrome screening programme.
  
  
  METHODS
  Population-based cohort study in the period July 2010 to June 2011 inclusive.
  
  
  METHODS
  Four Hong Kong Hospital Authority Departments of Obstetrics and Gynaecology and a central university-based laboratory for maternal serum processing and risk determination.
  
  
  METHODS
  Women were offered either a first-trimester combined test (nuchal translucency, free beta human chorionic gonadotropin, and pregnancy-associated plasma protein-A) or nuchal-translucency-only test, or a second-trimester double test (alpha-fetoprotein and total human chorionic gonadotropin) for detection of Down syndrome according to their gestational age. Those with a trisomy 21 term risk of 1:250 or higher were offered a diagnostic test.
  
  
  RESULTS
  A total of 16 205 pregnancies were screened of which 13 331 (82.3%) had a first-trimester combined test, 125 (0.8%) had a nuchal-translucency test only, and 2749 (17.0%) had a second-trimester double test. There were 38 pregnancies affected by Down syndrome. The first-trimester screening tests had a 91.2% (31/34) detection rate with a screen-positive rate of 5.1% (690/13 456). The second-trimester test had a 100% (4/4) detection rate with a screen-positive rate of 6.3% (172/2749). There were seven (0.9%) pregnancies that miscarried following an invasive diagnostic test. There were two Down syndrome-affected live births, both with an estimated first-trimester trisomy 21 term risk lower than 1:250.
  
  
  CONCLUSIONS
  The universal screening programme offered at the four units was effective and achieved the expected detection rates and low false-positive rates, and to maintain these, the current emphasis on training, quality control, and regular auditing must continue.
authors.affiliation: Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. daljit@cuhk.edu.hk
authors.forename: Daljit S
authors.initials: DS
authors.lastname: Sahota
authors.forename: W C
authors.initials: WC
authors.lastname: Leung
authors.forename: W P
authors.initials: WP
authors.lastname: Chan
authors.forename: William Wk
authors.initials: WW
authors.lastname: To
authors.forename: Elizabeth T
authors.initials: ET
authors.lastname: Lau
authors.forename: T Y
authors.initials: TY
authors.lastname: Leung
mesh_terms: D000293:Adolescent; D000328:Adult; D000649:Amniocentesis / Q000379:methods; D015331:Cohort Studies; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006723:Hong Kong; D006801:Humans; D008403:Mass Screening / Q000458:organization & administration*; D008423:Maternal Age; D062145:Maternal Serum Screening Tests / Q000379:methods; D008875:Middle Aged; D011247:Pregnancy; D011256:Pregnancy Outcome; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis / Q000379:methods*; D015397:Program Evaluation; D011446:Prospective Studies; D011785:Quality Assurance, Health Care; D018570:Risk Assessment; D016216:Ultrasonography, Prenatal / Q000379:methods; D055815:Young Adult
keywords: Down syndrome; First trimester screening; Nuchal translucency; Quality control; Second trimester screening