title: Pelvic CT morphometry in Down syndrome: implications for prenatal US evaluation--preliminary results.
abstract: OBJECTIVE
  To characterize pelvic morphometric differences in patients with and those without Down syndrome by using computed tomography (CT) and to determine useful indexes for ultrasonographic (US) evaluation.
  
  
  METHODS
  Pelvic CT scans in seven patients with Down syndrome and in 27 patients without Down syndrome were reviewed. Iliac angle, iliac length, sacroiliac joint angle, and anterior iliac wing separation were measured at superior, middle, and inferior transverse sacral levels. The effects of chromosomal status and transverse level were evaluated statistically.
  
  
  RESULTS
  Significant differences were found for mean iliac angle (P < .007) and length (P < .005) between patients without Down syndrome (angle, 75 degrees; length, 8.4 cm) and those with Down syndrome (angle, 82 degrees; length, 7.5 cm). Depending on the level of measurement, variations in iliac angle between patients without and those with Down syndrome were as much as 13 degrees and 15 degrees, respectively, and variations in length were as much as 1.6 cm and 0.9 cm, respectively. The greatest differences were at the middle sacral level. Sacroiliac joint angle and the anterior iliac wing separation were not different between groups.
  
  
  CONCLUSIONS
  Patients with Down syndrome had a larger mean iliac angle and a shorter mean iliac length. The most pronounced differences were at the middle sacral level, which suggests that this may be the optimal level for measuring these parameters at prenatal US.
authors.affiliation: Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA. freed005@mc.duke.edu
authors.forename: K S
authors.initials: KS
authors.lastname: Freed
authors.forename: M A
authors.initials: MA
authors.lastname: Kliewer
authors.forename: B S
authors.initials: BS
authors.lastname: Hertzberg
authors.forename: D M
authors.initials: DM
authors.lastname: DeLong
authors.forename: E K
authors.initials: EK
authors.lastname: Paulson
authors.forename: R C
authors.initials: RC
authors.lastname: Nelson
mesh_terms: D004314:Down Syndrome / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010384:Pelvic Bones / Q000002:abnormalities* / Q000473:pathology; D010387:Pelvimetry; D011247:Pregnancy; D012016:Reference Values; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D016216:Ultrasonography, Prenatal