title: Crown-rump lengths in missed miscarriages and trisomy 21.
abstract: OBJECTIVE
  To compare crown-rump lengths with karyotypes of missed miscarried fetuses and to determine a relationship between crown-rump length and trisomy 21.
  
  
  METHODS
  Chorionic villus sampling was performed on 129 consecutive missed miscarriages between 10 and 12 weeks by last menstrual period in patients >or= 35 years of age. Crown-rump length was correlated with the karyotype. Statistical analysis was performed using Student's t-test.
  
  
  RESULTS
  Twenty-one of 129 missed miscarriages involved fetuses affected by trisomy 21. The crown-rump length was < 22 mm in 77% of missed miscarriages. Using a crown-rump length of >or= 22 mm for the prediction of trisomy 21 had a sensitivity of 86%, specificity of 89%, positive predictive value of 60% and negative predictive value of 97%. At 10-12 weeks, the crown-rump lengths of missed miscarried fetuses with trisomy 21 was significantly larger (P <or= 0.0001) than that of the population average of missed miscarried fetuses.
  
  
  CONCLUSIONS
  In women >or= 35 years of age, with a missed miscarriage, in whom pregnancies reached >or= 10 weeks from the last menstrual period, a fetal crown-rump length of >or= 22 mm has a high probability that the etiology of the loss will be secondary to trisomy 21.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Medical Genetics, Illinois Masonic Hospital and Medical Center, Chicago, USA. nag709@nwu.edu
authors.forename: N A
authors.initials: NA
authors.lastname: Ginsberg
authors.forename: C
authors.initials: C
authors.lastname: Strom
authors.forename: Y
authors.initials: Y
authors.lastname: Verlinsky
mesh_terms: D000030:Abortion, Missed / Q000209:etiology*; D000328:Adult; D015193:Chorionic Villi Sampling; D018568:Crown-Rump Length; D004314:Down Syndrome / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007621:Karyotyping; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D018566:Pregnancy, High-Risk; D012189:Retrospective Studies; D012307:Risk Factors; D016216:Ultrasonography, Prenatal