Can Ultrasound Predict Labor Outcome in Operative Vaginal Deliveries?
Condition: Prolonged Labour
Study type: Observational

Summary: 
      To assess whether ultrasound methods can predict outcome of operative vaginal deliveries in
      nulliparous women at term with singleton pregnancies and prolonged second stage of labor.

      To compare different ultrasound assessments Compare digital assessments and ultrasound
      findings. Investigate if movement of the fetal head during active pushing is a predictive
      factor

      Null hypotheses:

        -  Ultrasound measurements cannot predict outcomes of operative vaginal delivery.

        -  Ultrasound is not better than digital examination in predicting delivery outcome.

        -  Movement of fetal head with active pushing is not a predictive factor.
    

Detailed description: 
      The physician responsible for the labor will perform digital examinations (fetal station and
      position and cervical dilatation). Fetal station will be related to the ischial spine from -5
      to +4 as described by WHO and illustrated in Figure 111. Another obstetrician or midwife
      blinded to the results from the clinical examination will perform the ultrasound
      measurements. The physician responsible for the labor will be blinded to the ultrasound
      measurements.

      Ultrasound examinations between contractions

      Due to considerations described below, only one recording/acquisition will be performed of
      each of the following:

      A) Head position B) Head-perineum distance C) Midline angle D) Angle of progression E) 3D
      sagittal transperineal acquisition In addition single scans are performed during active
      pushing as described under B) and D) (and a 3D sagittal scan when possible).

      A) Head position Position will be assessed in 2D with a transabdominal scan as described by
      Akmal4 and 3D in a transperineal scan as described by Ghi et al22. Fetal head position will
      be recorded as a clock dividing the circle in 24 divisions

      Positions ≥02.30 and ≤03.30 hours should be recorded as left occiput transverse and positions
      ≥08.30 and ≤09.30 as right occiput transverse. Positions >03.30 and <08.30 should be recorded
      as occiput posterior and positions >09.30 and <02.30 as occiput anterior.

      Head-perineum distance will be assessed with transperineal ultrasound. The women will be
      examined lying flat (or almost flat) in bed with flexed hips and knees position. The bladder
      should be emptied immediately before the ultrasound examination.

      Head-perineum distance will be measured as the shortest distance between the outer bony limit
      of the fetal skull and the perineum with a transabdominal transducer placed transperineally
      between the labia in a transverse view (posterior fourchette - posterior commissure of the
      labia minor)

      Midline angle will be measured as described by Ghi22. In a transverse transperineal scan the
      angle between the midline of the fetal head and a sagittal line through the maternal pelvis
      will be measured. This recording will also be performed in a transverse scan.

      Angle of progression will be measured as described by Barbera and Kalache as the angle
      between the long axis of the symphysis pubis and the tangent of the skull in a transperineal
      sagittal scan.

      The following outcome variables will be recorded upon delivery Main outcome

        -  Time from start of vacuum assisted traction to delivery (the entire body is delivered)
           Secondary outcomes

        -  Number of contraction before delivery

        -  Number of cup detachments

        -  Successful/failed vaginal operative delivery

        -  Forceps applied/not applied

        -  Perineal tears

        -  APGAR score of newborn.

        -  Arterial umbilical cord blood pH and BD (base deficit) values.

        -  Position at delivery

      Statistics:

      The time interval between start of operative vaginal delivery and delivery will be evaluated
      for the fetal head-perineum distance and angle of progression using survival analyses
      (Kaplan-Meier analyses and Cox regression analyses).

      Categorical variables will be analyzed using Chi-square test and Fischer exact test, and
      continuous variable will be analyzed using T-test or Mann-Whitney U-test.

      The predictive values for a successful operative vaginal delivery will be evaluated using
      receiver-operating characteristics (ROC) curves. The area under the curve (AUC, - 95% CI) is
      considered to have discriminatory potential if the lower limit of the CI exceeded 0.5.

      Ultrasound measurements, digital assessment of station and dilatation, induction of labor,
      maternal age, gestational age and birth weight will be analyzed in logistic regression
      analyses with vaginal delivery vs. cesarean section as dependent variable.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Nulliparous women with a singleton live fetus in cephalic presentation at term (≥ 37 weeks)
        with prolonged active second stage and a clinical decision to expedite delivery by vacuum
        due to poor progression
      
Keywords: labour; dystocia; operative delivery; vacuum; ultrasound