title: The reliability of transabdominal cervical length measurement in a low-risk obstetric population: Comparison with transvaginal measurement.
abstract: OBJECTIVE
  To determine the correlation between transabdominal (TA) and transvaginal (TV) cervical length measurement in a low-risk obstetric population in Taiwan.
  
  
  METHODS
  Women with a singleton pregnancy between 20 weeks and 24 weeks of gestation underwent postvoid TA and TV cervical length measurements. Differences between the measurements obtained using the two methods were evaluated.
  
  
  RESULTS
  Two hundred and five women agreed to participate in the study. Paired TA and TV measurements were obtained in 174 women. The mean TA cervical length was 36.0 ± 4.9 mm and the mean TV cervical length was 37.6 ± 5.4 mm. The mean TA cervical length was shorter than the mean TV cervical length by 1.6 mm. The 5(th) percentile of TA and TV cervical length was 29 mm and 29.1 mm, respectively. The discrepancies between the two methods were not significantly correlated with maternal body mass index (BMI). All women with TV cervical length <25 mm had a corresponding TA cervical length <29 mm.
  
  
  CONCLUSIONS
  The TA cervical length could be obtained in the majority of the low-risk pregnant women in the present study, and the TA cervical length was closely correlated with the TV cervical length. The use of TA ultrasound could be an effective initial tool for cervical length screening in low-risk pregnant women. TA cervical length <29 mm (5(th) percentile) could be used as a cut-off value for further TV ultrasound.
authors.affiliation: Division of High Risk Pregnancy, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Cheng-Ran
authors.initials: CR
authors.lastname: Peng
authors.affiliation: Division of High Risk Pregnancy, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Chie-Pein
authors.initials: CP
authors.lastname: Chen
authors.affiliation: Division of High Risk Pregnancy, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Kuo-Gon
authors.initials: KG
authors.lastname: Wang
authors.affiliation: Division of High Risk Pregnancy, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
authors.forename: Liang-Kai
authors.initials: LK
authors.lastname: Wang
authors.affiliation: Division of High Risk Pregnancy, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan; Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan; Mackay Medical College, Taipei, Taiwan.
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Division of High Risk Pregnancy, Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan. Electronic address: yiyung.chen@gmail.com.
authors.forename: Yi-Yung
authors.initials: YY
authors.lastname: Chen
mesh_terms: D000005:Abdomen; D000328:Adult; D054791:Cervical Length Measurement / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D047928:Premature Birth / Q000517:prevention & control*; D011446:Prospective Studies; D015203:Reproducibility of Results; D012306:Risk; D014621:Vagina
keywords: cervical length screening; preterm delivery; transabdominal ultrasound