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135: Pregnancy outcome and mode of delivery following a previous operative vaginal delivery

      Objective

      Limited data exists regarding the consequences of operative vaginal delivery(OVD) on subsequent pregnancies. Our aim was to assess pregnancy outcome and mode of delivery in women with a previous OVD.

      Study Design

      A case control study of all nulliparous women who underwent OVD in a single tertiary center during 1993-2006 (N=4153). The control group included nulliparous women who underwent spontaneous vaginal delivery(SVD) during this time period in a 2:1 ratio, matched by maternal age and gestational age at delivery (N=8306). The outcome of subsequent delivery for women in the study and control groups was compared (N=1396 and N=2591,respectively). Women with multiple-gestations, non-vertex presentations, or any other contraindications for vaginal delivery were excluded.

      Results

      1)Out of 83,351 deliveries during the study period, 5,120 (6.1%) were by OVD, of which 81% involved nulliparous women(N=4153). 2) Women with a previous OVD were at increased risk for recurrent OVD (OR=3.9, 95%-CI 2.5-5.9) and CS (OR=1.9, 95%-CI 1.5-2.5) on subsequent pregnancy. 2) Prolonged 2nd stage was the most common indication for recurrent OVD (80%)in women with a previous OVD, compared with only 34% in women with a previous SVD. 3)The risk of intrapartum-neonatal trauma(1.5% vs. 0.6%) and 3rd-4th-degree lacerations (0.7% vs. 0.2%) was significantly higher in the group of women with a previous OVD (p<0.01). 4)The following factors were associated with increased risk for recurrent OVD: failed vacuum extraction (OR=2.8, 95%-CI 1.4-5.8), prolonged 2nd-stage as the indication for OVD (OR=2.1, 95%-CI 1.2-3.6) on the index pregnancy, time from first pregnancy >3y (OR=3.8, 95%-CI 1.2-12.5), higher fetal-weight on subsequent pregnancy (OR=2.1, 95%-CI 1.2-3.3), and persistent occipito-posterior position (OR=13.8, 95%-CI 4.8-21.2) and the use of epidural (OR=1.8, 95%-CI 1.1-3.3) during subsequent pregnancy.

      Conclusion

      Nulliparous women undergoing OVD are at increased risk for recurrent OVD, cesarean section, perineal trauma and neonatal trauma upon their subsequent pregnancy.