title: Prenatal diagnosis versus first-trimester screening of trisomy 21 among pregnant women aged 35 or more.
abstract: OBJECTIVE
  To compare the policy of prenatal diagnosis versus first trimester screening of trisomy 21 among pregnant women of advanced age.
  
  
  METHODS
  A retrospective study was conducted on patients aged ≥35 divided in two groups: patients who requested first trimester combined test and only in case of screen-positive result underwent invasive testing (group A); patients undergoing chorionic villous sampling or amniocentesis as first investigation (group B). The following outcome variables were compared: antenatal detection of trisomy 21, occurrence of trisomy 21 at birth, miscarriage rate, hospitals' costs.
  
  
  RESULTS
  4527 women were included. Of these, 534 (11.80%) underwent T21 screening whereas 3993 (88.20%) requested primary invasive testing. In group A, 64 combined test were positive (11.99%) and 8 trisomy 21 cases were diagnosed (1.50%); the loss of euploid fetuses after invasive procedure was 4.55% (2/44). No false-negative case was observed. In group B 57 cases of trisomy 21 were diagnosed (1.43%), and pregnancy loss rate of chromosomally normal fetuses was 0.45% (17/3806). The estimated cost was, respectively, 67.720€ for the primary screening versus 1.996.500€ for direct prenatal diagnosis.
  
  
  CONCLUSIONS
  First trimester screening of trisomy 21 is highly accurate and cost saving among women ≥35.
authors.affiliation: Department of Obstetrics and Gynaecology, Sant'Orsola-Malpighi Hospital, University of Bologna , Bologna , Italy.
authors.forename: Tullio
authors.initials: T
authors.lastname: Ghi
authors.forename: Tiziana
authors.initials: T
authors.lastname: Arcangeli
authors.forename: Francesca
authors.initials: F
authors.lastname: Ravennati
authors.forename: Ginevra
authors.initials: G
authors.lastname: Salsi
authors.forename: Elisa
authors.initials: E
authors.lastname: Montaguti
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Pacella
authors.forename: Elisa
authors.initials: E
authors.lastname: Maroni
authors.forename: Maria Carla
authors.initials: MC
authors.lastname: Pittalis
authors.forename: Eva
authors.initials: E
authors.lastname: Pompilii
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Pilu
authors.forename: Nicola
authors.initials: N
authors.lastname: Rizzo
mesh_terms: D000025:Abortion, Eugenic / Q000706:statistics & numerical data; D000328:Adult; D015193:Chorionic Villi Sampling / Q000009:adverse effects / Q000706:statistics & numerical data; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D005313:Fetal Death / Q000209:etiology; D006801:Humans; D007231:Infant, Newborn; D008403:Mass Screening / Q000379:methods / Q000706:statistics & numerical data; D008423:Maternal Age; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D011261:Pregnancy Trimester, First / Q000097:blood; D011296:Prenatal Diagnosis / Q000009:adverse effects / Q000379:methods* / Q000706:statistics & numerical data; D012189:Retrospective Studies
keywords: Aneuploidies; invasive procedures; prenatal screening; screening