Title: Failed operative vaginal delivery – can it be predicted?
Abstract: To identify factors predicting failure of operative vaginal delivery. A retrospective cohort study of all women who underwent a trial of operative vaginal delivery between 1993 and 2006. Vacuum extraction or low forceps delivery were initially employed by physician's preference, and in cases of failed vacuum extraction either a cesarean section or a trial of forceps delivery were performed. 1) Out of 83,351 deliveries, the rate of operative vaginal delivery was 6.1% (5,120/83,351), and vacuum extraction (n=4299, 84.0%) was more common as the initial procedure compared with forceps delivery (n=821, 16.0%). 2) Failed operative delivery occurred in 8.6% (n=443) of these cases, and was significantly less common with forceps delivery than with vacuum extraction (10.0% vs. 1.3% p<0.001). 3) When vacuum extraction failed, a trial of forceps delivery was undertaken in 72.6% (n=314) of the cases with a 3.5% failure rate. 4) Failure of operative delivery was significantly more common in the case of macrosomia (8.9% vs. 2.6%, p<0.0001), persistent occipito-posterior (4.3% vs. 2.6%, p=0.03), and in the absence of analgesia (4.9% vs. 2.5%, p<0.001). 5) When analgesia was provided, the use of intravenous opiates was associated with a lower failure rate compared with epidural (1.2% vs. 2.6%, p<0.05). 6) On multivariate logistic regression analysis, the choice of forceps delivery rather than vacuum extraction (OR=0.37, 95% −CI=0.19-0.72), use of analgesia (OR=0.40, 95% −CI=0.26-0.63), persistent occipito-posterior (OR=1.80, 95% −CI=1.09-2.96), and macrosomia (OR=2.16, 95% −CI=1.17-3.98) were significant and independent predictors of failed operative delivery. Our data suggest that fetal weight and fetal head position should be included in the evaluation that precedes operative vaginal delivery. The use of analgesia should be encouraged prior to operative delivery.