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Trial of instrumental delivery: a retrospective cohort study
  1. N Panagiotopoulou,
  2. K Gossage,
  3. C Rice
  1. North Manchester General Hospital, Manchester, UK


Introduction 10–15% of all vaginal births,1,2 require operative delivery. In a minority of these cases, a trial of instrumental delivery in theatre is advisable. However this is associated with longer time interval to delivery and potential increased risks of perinatal mortality and morbidity.

Objectives Assessment of trials of instrumental delivery in theatre. Outcomes: reason for decision, success rate and decision-to-delivery intervals.

Methods Retrospective cohort of 41 women who underwent trial of instrumental delivery in theatre at North Manchester General Hospital, Pennine Acute NHS Trust over 9 months.

Results 2030 deliveries occurred at NMGH in 9 months. Operative vaginal delivery rate was 9%. 41 (2%) were managed as a trial in theatre. Mid cavity delivery was the indication in the majority of cases (83%) while more than one indication was present in 70% of cases. The success rate was 70% with 29 women achieved a vaginal delivery. Mid cavity was the risk factor for the majority of women (66.67%) who had a Caesarean section delivery followed by occipito-posterior position (58%). Epidural top-up or spinal analgesia was used with no statistical significant difference the success (OR 2.4, 95% CI 0.51 to 11.19, p=0.23). The mean decision-to-delivery interval was 50 min (31, 150 min).

Prostin (n=23)Propess (n=30)Balloon (n=25)
Initial Bishop's score33.33.7
Induction-delivery mean34 h 45 min28 h 40 min26 h 20 min
Induction-delivery median31 h23 h 20 min26 h 35 min
Vaginal delivery (%)676764
Instrumental delivery (%)1216.511
Caesarean section (%)2116.525
Neonatal unit admission210
Mean birthweight (g)342935743190
Nights hospital stay3.62.62.

Conclusion Mid cavity delivery was the most common indication for trial of instrumental delivery and most common reason for failed delivery. Decision-to-delivery interval is prolonged in cases of trials of instrumental delivery, this could lead to significant mortality or morbidity.

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