title: Transabdominal evaluation of uterine cervical length during pregnancy fails to identify a substantial number of women with a short cervix.
abstract: OBJECTIVE
  To assess the diagnostic performance of transabdominal sonographic measurement of cervical length in identifying patients with a short cervix.
  
  
  METHODS
  Cervical length was measured in 220 pregnant women using transabdominal and transvaginal ultrasound (US). Reproducibility and agreement between and within both methods were assessed. The diagnostic accuracy of transabdominal US for identifying cases with a cervical length <25 mm was evaluated.
  
  
  RESULTS
  Twenty-one out of 220 cases (9.5%) had a cervical length <25 mm by transvaginal US. Only 43% (n = 9) of patients with a short cervix were correctly identified by transabdominal US. In patients with a cervical length of <25 mm by transvaginal US, transabdominal measurement of the cervix overestimated this parameter by an average of 8 mm (95% LOAs, -26.4 to 10.5 mm). Among women without a short cervix, transabdominal US underestimated cervical length on average (LOA) by 1.1 mm (95% LOAs, -11.0 to 13.2 mm). Transvaginal US was also more reproducible (intraclass correlation coefficient: (ICC) (0.96; 95% CI, 0.94 to 0.97) based on comparisons between 2D images and immediately acquired 3D volume datasets relative to transabdominal US (ICC: 0.71; 95% CI, 0.57 to 0.84). Transvaginal US detected 13 cases with funneling and six cases with sludge whereas only three cases of funneling and one of sludge were detected by transabdominal US.
  
  
  CONCLUSIONS
  Transabdominal measurement overestimated cervical LOA by 8 mm among women with a short cervix and resulted in the underdiagnosis of 57% of cases.
authors.affiliation: Perinatology Research Branch, NICHD, NIH, DHHS, Detroit, MI 48201, USA.
authors.forename: Edgar
authors.initials: E
authors.lastname: Hernandez-Andrade
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
authors.forename: Hyunyoung
authors.initials: H
authors.lastname: Ahn
authors.forename: Youssef
authors.initials: Y
authors.lastname: Hussein
authors.forename: Lami
authors.initials: L
authors.lastname: Yeo
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Korzeniewski
authors.forename: Tinnakorn
authors.initials: T
authors.lastname: Chaiworapongsa
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Hassan
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging; D000293:Adolescent; D000328:Adult; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging* / Q000517:prevention & control; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging / Q000453:epidemiology; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal / Q000379:methods* / Q000706:statistics & numerical data; D014621:Vagina / Q000000981:diagnostic imaging; D055815:Young Adult