title: Prediction of delivery mode with transperineal ultrasound in women with prolonged first stage of labor.
abstract: OBJECTIVE
  To investigate if fetal head-perineum distance and angle of progression measured with two-dimensional (2D) and three-dimensional (3D) transperineal ultrasound could predict outcome of labor in primiparous women with prolonged first stage of labor.
  
  
  METHODS
  This was a prospective observational study of 110 primiparous women with singleton cephalic presentation at term diagnosed with prolonged first stage of labor. Digital assessment of fetal station was related to the ischial spine. Fetal head descent was measured with transperineal ultrasound as the shortest distance from the fetal head to the perineum, and the angle between the pubic symphysis and the fetal head. Receiver-operating characteristics (ROC) curves were constructed and 2D and 3D data acquisitions were compared. The stored 3D volumes were assessed by an examiner blinded to all other data. Vaginal delivery vs. Cesarean section was the primary outcome.
  
  
  RESULTS
  Cesarean section was performed in 25% of the women. Areas under the ROC curves for prediction of vaginal delivery were 81% (95% confidence interval (CI), 71-91%) (P < 0.01) and 76% (95% CI, 66-87%) (P < 0.01) for fetal head-perineum distance and angle of progression, respectively, as measured by 2D ultrasound and 66% (95% CI, 54-79%) for digital assessment of fetal station (P = 0.01). In 50% of women fetal head-perineum distance was ≤ 40 mm and 93% (95% CI, 83-97%) of them delivered vaginally vs. 18% (95% CI, 5-48%) with distance > 50 mm. In 48% of women the angle of progression was ≥ 110° and 87% (95% CI, 75-93%) of them delivered vaginally vs. 38% (95% CI, 21-57%) with angle < 100°. Results from 2D and 3D acquisitions were similar.
  
  
  CONCLUSIONS
  Fetal head-perineum distance and angle of progression measured with 2D or 3D ultrasound can predict labor outcome, with similar predictive values for the two techniques.
authors.affiliation: Department of Obstetrics and Gynecology, Stavanger University Hospital, Stavanger, Norway. eatorkildsen@hotmail.com
authors.forename: E A
authors.initials: EA
authors.lastname: Torkildsen
authors.forename: K Å
authors.initials: KÅ
authors.lastname: Salvesen
authors.forename: T M
authors.initials: TM
authors.lastname: Eggebø
mesh_terms: D000293:Adolescent; D000328:Adult; D002584:Cervix Uteri / Q000000981:diagnostic imaging*; D002585:Cesarean Section / Q000379:methods / Q000706:statistics & numerical data*; D036861:Delivery, Obstetric / Q000379:methods*; D005260:Female; D005333:Fetus / Q000033:anatomy & histology; D006801:Humans; D007746:Labor Presentation; D007743:Labor, Obstetric / Q000502:physiology; D010502:Perineum / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011446:Prospective Studies; D016216:Ultrasonography, Prenatal / Q000379:methods; D055815:Young Adult