title: Routine ultrasonography compared with maternal serum alpha-fetoprotein for neural tube defect screening.
abstract: OBJECTIVE
  This study was done to estimate the value of prenatal maternal serum alpha-fetoprotein (MSAFP) screening compared with that of routine ultrasonography in the diagnosis of neural tube defects (NTDs).
  
  
  METHODS
  An integrated database was used retrospectively to identify cases of NTDs among 219,000 consecutive pregnancy outcomes observed during a 7-year period at 40 Kaiser Permanente facilities in Northern California. We specifically examined types of NTD and the tests used to diagnose cases.
  
  
  RESULTS
  We identified 189 NTD cases, 102 of which had received MSAFP screening. Results of MSAFP testing were negative in 25 (25%) of these 102 cases. Without other testing, these 25 NTD diagnoses would have been missed. These included 15 (38%) of the 40 spina bifida cases screened, 6 (67%) of the 9 encephalocele cases screened, and 4 (8%) of the 53 anencephaly cases screened. Of the 186 NTD cases diagnosed prenatally, 115 (62%) were initially detected by routine ultrasonography administered during the second trimester without knowledge of MSAFP values; 69 (37%) were diagnosed by targeted ultrasonography after MSAFP screening indicated a higher risk for NTD; and 2 (1%) were diagnosed by pathology examination after miscarriage.
  
  
  CONCLUSIONS
  Compared with MSAFP performed alone for screening, routine second-trimester ultrasonography was more likely to discover an NTD.
authors.affiliation: Regional Perinatal Screening Section, Department of Genetics, Kaiser Permanente Medical Care Program, Oakland, California 94611-5963, USA.
authors.forename: Carol T
authors.initials: CT
authors.lastname: Norem
authors.forename: Edgar J
authors.initials: EJ
authors.lastname: Schoen
authors.forename: David L
authors.initials: DL
authors.lastname: Walton
authors.forename: Robyn C
authors.initials: RC
authors.lastname: Krieger
authors.forename: Jennifer
authors.initials: J
authors.lastname: O'Keefe
authors.forename: Trinh T
authors.initials: TT
authors.lastname: To
authors.forename: G Thomas
authors.initials: GT
authors.lastname: Ray
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis*; D006801:Humans; D009436:Neural Tube Defects / Q000097:blood / Q000175:diagnosis*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011256:Pregnancy Outcome; D011262:Pregnancy Trimester, Second / Q000097:blood; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D000509:alpha-Fetoproteins