title: Prenasal Thickness, Prefrontal Space Ratio and Other Facial Profile Markers in First-Trimester Fetuses with Aneuploidies, Cleft Palate, and Micrognathia.
abstract: OBJECTIVE
  To investigate the feasibility and reproducibility of the prenasal thickness (PNT)/nasal bone length (NBL) ratio, maxilla-nasion-mandible (MNM) angle, facial profile line, profile line distance, and prefrontal space ratio (PFSR) in the first trimester of pregnancy, develop normal ranges, and evaluate these markers in abnormal fetuses.
  
  
  METHODS
  All measurements were performed on stored images by two operators. Feasibility, interoperator agreement, and prediction intervals were calculated for all measurements.
  
  
  RESULTS
  Feasibility was the highest for the NBL (74.3-79.7%) and the MNM angle (75.7-79.05%). Correlation was good for the NBL, the PNT, and the MNM angle (intraclass correlation coefficient 0.706-0.835). Mean difference between operators was the lowest for the PNT and PFSR (0.03-0.08). Measurements in abnormal fetuses showed that the majority of trisomy 21 fetuses had either an absent nasal bone or a shorter NBL. The PNT and PNT/NBL ratio were above the 97.5th centile in one third of the cases. Fetuses with facial clefts or micrognathia showed on average a large MNM angle (multiple of the median 0.96-5.15).
  
  
  CONCLUSIONS
  First-trimester facial markers are feasible. The PNT and PNT/NBL ratio were increased in one third of the trisomic fetuses, and the MNM angle in the majority of fetuses with micrognathia and facial clefts.
authors.affiliation: Department of Obstetrics and Gynecology, Fetal Medicine Unit, University Medical Centre, Groningen, The Netherlands.
authors.forename: Merel
authors.initials: M
authors.lastname: Bakker
authors.forename: Margherita
authors.initials: M
authors.lastname: Pace
authors.forename: Els
authors.initials: E
authors.lastname: de Jong-Pleij
authors.forename: Erwin
authors.initials: E
authors.lastname: Birnie
authors.forename: Karl-Oliver
authors.initials: KO
authors.lastname: Kagan
authors.forename: Caterina M
authors.initials: CM
authors.lastname: Bilardo
mesh_terms: D002972:Cleft Palate / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D004314:Down Syndrome / Q000000981:diagnostic imaging; D005145:Face / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008844:Micrognathism / Q000000981:diagnostic imaging; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal
keywords: Facial profile line; First trimester; Maxilla-nasion-mandible angle; Nasal bone; Prefrontal space ratio; Prenasal thickness/nasal bone length ratio; Prenatal screening; Prenatal thickness