title: Magnetic resonance imaging of the cervix during pregnancy: effect of gestational age and prior vaginal birth.
abstract: OBJECTIVE
  To investigate how gestational age and prior vaginal birth affect cervical anatomy on magnetic resonance imaging during pregnancy.
  
  
  METHODS
  Magnetic resonance images of the cervix were obtained in consecutive patients referred for a suspected fetal abnormality. We used an image processing protocol to measure cervical dimensions, orientation, and signal intensity. We determined how outcome variables were affected by gestational age and prior vaginal birth.
  
  
  RESULTS
  Adequate images were obtained in 53 of 57 patients at 17 to 36 weeks. As gestational age increased by 12 weeks, the mean cross-sectional area of the cervical canal and cervical stroma increased 31% (95% confidence interval 0% to 73%) and 31% (95% confidence interval 11% to 55%), respectively. The normalized signal intensity of the stroma increased from 0.83 (95% confidence interval 0.81 to 0.85) at 20 weeks to 0.91 (95% confidence interval 0.88 to 0.94) at 32 weeks. None of the outcome variables were affected by prior vaginal birth.
  
  
  CONCLUSIONS
  Magnetic resonance imaging revealed that cross-sectional area and signal intensity of the cervical stroma increase with increasing gestational age.
authors.affiliation: Division of Maternal-Fetal Medicine, Tufts-New England Medical Center, Boston, MA, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: House
authors.forename: Mark
authors.initials: M
authors.lastname: O'Callaghan
authors.forename: Stephane
authors.initials: S
authors.lastname: Bahrami
authors.forename: David
authors.initials: D
authors.lastname: Chelmow
authors.forename: Jonathan
authors.initials: J
authors.lastname: Kini
authors.forename: Danny
authors.initials: D
authors.lastname: Wu
authors.forename: Samuel
authors.initials: S
authors.lastname: Patz
authors.forename: Rafeeque A
authors.initials: RA
authors.lastname: Bhadelia
mesh_terms: D000328:Adult; D002584:Cervix Uteri / Q000033:anatomy & histology*; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third