title: Second-Trimester Anterior Cervical Angle in a Low-Risk Population as a Marker for Spontaneous Preterm Delivery.
abstract: OBJECTIVE
  The aim of this article is to assess the use of the anterior cervical angle (ACA) as a predictor of spontaneous preterm delivery (sPTD) at 20+0-24+6 weeks of gestation in an unselected population.
  
  
  METHODS
  We conducted a nested case-control study that included 93 women who later delivered spontaneously <34 weeks of gestation and 225 controls. The ACA was assessed retrospectively on all selected images using ImageJ® software. The concordance correlation coefficient was determined for the assessment of interobserver variability. Continuous variables were adjusted by maternal characteristics and expressed as the z-score or multiples of the expected normal median (MoM) of the unaffected group. Logistic regression analysis was used to evaluate whether any maternal characteristics and ultrasound variables were significantly associated with sPTD <34 weeks.
  
  
  RESULTS
  ACA z-score values were significantly greater in women who later delivered <34 weeks compared to controls (ACA z-score = 1.32 ± 0.57 vs. -0.09 ± 0.35; p = 0.035). The best prediction of sPTD <34 weeks was provided by a model that combined cervical length (CL) MoM, ACA z-score and maternal characteristics. For a fixed false-positive rate of 10%, the detection rate for this model was 37.6%.
  
  
  CONCLUSIONS
  A model combining maternal history, CL and ACA at 20+0-24+6 weeks of gestation can predict approximately 40% of the severe preterm births.
authors: Fetal Medicine Unit, Department of Obstetrics and Gynecology, Hospital Clínico, Universidad de Chile, Santiago, Chile.
authors: Alvaro
authors: A
authors: Sepúlveda-Martínez
authors: Francisco
authors: F
authors: Díaz
authors: Hernán
authors: H
authors: Muñoz
authors: Enrique
authors: E
authors: Valdés
authors: Mauro
authors: M
authors: Parra-Cordero
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007752:Obstetric Labor, Premature / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000502:physiology; D047928:Premature Birth / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Cervical angle; Cervical length; Preterm delivery; Screening; Second trimester