title: Normal midtrimester (17-20 weeks) genetic sonogram decreases amniocentesis rate in a high-risk population.
abstract: OBJECTIVE
  To evaluate a screening protocol using advanced maternal age, triple-marker screening, and genetic sonography.
  
  
  METHODS
  We compared adverse chromosomal outcomes of pregnancy in 1556 women referred for increased risk of aneuploidy because of either advanced maternal age or triple-marker test results. Patients were counseled about the results of the triple-marker test and subsequent sonography, which led to a patient decision of whether to pursue amniocentesis. Fetal measurements and structural abnormalities were compared with chromosomal findings. When patients elected amniocentesis, karyotypes were obtained.
  
  
  RESULTS
  Genetic sonography reduced the rate of amniocentesis by 61% overall and by 40% when compared with an alpha-fetoprotein profile alone. The sensitivity of sonography combined with the triple-marker screen for the detection of trisomy 21 was 87% compared with 91% for the triple-marker screen alone.
  
  
  CONCLUSIONS
  This study confirmed that sonographic findings in a targeted population, in combination with other risk markers (advanced maternal age and triple-marker screening), can be used to assess the risk of aneuploidy. Biometry provides additional information for assessing the risk of aneuploidy. Combining advanced maternal age, serum triple-marker screening, and sonographic screening may provide better risk prediction for use in clinical counseling.
authors.affiliation: Department of Obstetrics and Gynecology, Maine Medical Center, Portland 04102, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Pinette
authors.forename: J
authors.initials: J
authors.lastname: Garrett
authors.forename: A
authors.initials: A
authors.lastname: Salvo
authors.forename: J
authors.initials: J
authors.lastname: Blackstone
authors.forename: S G
authors.initials: SG
authors.lastname: Pinette
authors.forename: N
authors.initials: N
authors.lastname: Boutin
authors.forename: A
authors.initials: A
authors.lastname: Cartin
mesh_terms: D000649:Amniocentesis / Q000706:statistics & numerical data*; D004314:Down Syndrome / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D012307:Risk Factors; D016216:Ultrasonography, Prenatal