title: Can Transabdominal Cervical Length Measurement Exclude Short Cervix?
abstract: OBJECTIVE
  This study aims to determine if transabdominal (TA) cervical length may be used to rule out a short cervix on transvaginal (TV) ultrasound.
  
  
  METHODS
  We conducted a prospective cohort study of women undergoing routine anatomic survey at 17 to 23 weeks gestation. TA and TV cervical length measurements were obtained in each patient. A short cervix was defined as TV cervical length < 30 mm. Predictive characteristics were calculated for different cutoff values of TA cervical length.
  
  
  RESULTS
  There were 404 patients enrolled, a TA cervical length could not be obtained in 83 women (20.6%) and 318 women had both TA and TV measurements. Of those, 14 (4.4%) had a TV cervical length < 30 mm. TA cervical length measurement ≥ 35 mm excluded the possibility of TV cervical length < 30 mm (negative predictive value, 99.5%; 95% confidence interval [CI], 97.4; 100%). In our cohort, 67.6% (95% CI, 62.2; 72.7%) of TV ultrasounds could have been avoided using a TA cervical length cutoff of ≥ 5 mm.
  
  
  CONCLUSIONS
  ATA cervical length of at least 35 mm excludes a short cervix of < 30 mm. While TA cervical length screening may not be feasible in 1 in 5 women, it may be used to decrease the burden of universal TV cervical length screening.
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Janine S
authors.initials: JS
authors.lastname: Rhoades
authors.affiliation: Department of Obstetrics and Gynecology, Hartford Hospital, Hartford, Connecticut.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Park
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Molly J
authors.initials: MJ
authors.lastname: Stout
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: George A
authors.initials: GA
authors.lastname: Macones
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Alison G
authors.initials: AG
authors.lastname: Cahill
authors.affiliation: Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Methodius G
authors.initials: MG
authors.lastname: Tuuli
mesh_terms: D000328:Adult; D054791:Cervical Length Measurement / Q000379:methods*; D002584:Cervix Uteri / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D009929:Organ Size; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011446:Prospective Studies; D014463:Ultrasonography / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods; D055815:Young Adult