title: Combined ultrasound and biochemistry for risk evaluation in the first trimester: the Stockholm experience of a new web-based system.
abstract: OBJECTIVE
  To evaluate the performance of a new first trimester web-based software for the detection of chromosomal anomalies using a combination of ultrasound and biochemistry.
  
  
  METHODS
  Registry-based cohort study.
  
  
  METHODS
  Ultrasound units in the Stockholm region.
  
  
  METHODS
  20 710 women with singleton pregnancies were examined at 11(+0) to 13(+6) weeks' gestational age during a three-year period 2006-2009.
  
  
  METHODS
  The risks for trisomy 21, 13 and 18 were calculated using a combination of maternal age, serum markers and nuchal translucency. Individual risk estimates were calculated and then reported to a web-based system using a new algorithm based on likelihood ratios of each marker derived from Gaussian distributions in normal and affected pregnancies.
  
  
  METHODS
  The impact on rates of invasive testing and the incidence of children born with Down's syndrome after implementing the method.
  
  
  RESULTS
  Approximately a third of all pregnant women in the region were examined with the combined test. The detection and test positive rates for Down's syndrome was 90 and 6.8%, respectively. Invasive testing among pregnant women decreased from 15 to 8% after introducing the method but the incidence of children born with Down's syndrome did not decrease during the study period.
  
  
  CONCLUSIONS
  The new web-based software is an effective method for the detection of trisomy 21 with similar performance compared to other programs. However, it needs to be offered to all pregnant women to have an impact on the incidence of Down's syndrome.
authors: Obstetrics and Gynecology Karolinska University Hospital.
authors: Peter
authors: P
authors: Conner
authors: Obstetrics and Gynecology Karolinska University Hospital.
authors: Magnus
authors: M
authors: Westgren
authors: Ultragyn, Danderyds Hospital.
authors: Anna
authors: A
authors: Marsk
authors: Clinical Chemistry, Karolinska University Hospital, Stockholm, Sweden.
authors: Sven
authors: S
authors: Gustafsson
authors: Obstetrics and Gynecology Karolinska University Hospital.
authors: Marius
authors: M
authors: Kublickas
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D025063:Chromosome Disorders / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D002882:Chromosomes, Human, Pair 13 / Q000000981:diagnostic imaging; D002887:Chromosomes, Human, Pair 18; D004314:Down Syndrome / Q000097:blood / Q000175:diagnosis / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D015994:Incidence; D020407:Internet; D008875:Middle Aged; D048208:Nuchal Translucency Measurement; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism*; D011446:Prospective Studies; D012042:Registries; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012984:Software; D013548:Sweden / Q000453:epidemiology; D014314:Trisomy / Q000175:diagnosis; D000073839:Trisomy 13 Syndrome; D055815:Young Adult
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A