Fear of failure: are we doing too many trials of instrumental delivery in theatre?

Objectives: Cesarean section has largely replaced the role of difficult midcavity instrumental deliveries. The aim of this study was to determine the trend in trials of instrumental delivery as well as the maternal and fetal factors associated with successful and failed trial of instrumental deliveries.
Setting: North Middlesex University Hospital, a teaching hospital in London.
Study Design: A retrospective review of trials of instrumental delivery in theatre involving singleton term pregnancies between 2000 and 2005.
Results: Of the 114 trials, 82 (40 forceps and 42 vacuum extraction) were successful. Women who had successful trials were similar in age (27.8+/-5.9 vs. 27.1+/-5.4 yrs), gestation (40.5+/-2.1 vs. 40.5+/-1.1 wks) and parity (0.4+/-1.2 vs. 0.3+/-1.6) when compared to those who were unsuccessful (p>0.05). The two groups also had similar birth weight (3.6+/-0.7 vs. 3.7+/-0.4 kg) and duration of second stage (164.9+/-12.0 vs. 162.8+/-16.0 min) (p>0.05). Babies born following failed trial of instrumental deliveries were more likely to be acidotic (p=0.014) but admission to Special Care Baby Unit was similar in both groups. Women who had failed trials of instrumental delivery were more likely to have post-partum hemorrhage (802.7+/-100.0 vs. 425.4+/-120.0 ml) and pyrexia (15.6% vs. 6.1%) (p<0.05). Trial of instrumental delivery was twice as likely to fail if occipito-posterior and three times more likely to succeed if the presenting part was visible (p<0.05). However, 25% of babies had presenting parts well below the ischial spines but still had instrumental deliveries in theatre and 80% of this subgroup were delivered by junior trainees. Although 71.9% of trials of instrumental delivery were successful, many were relatively uncomplicated and did not necessarily require delivery in theatre.
Conclusion: Unsuccessful trials are associated with maternal rather than neonatal morbidity. The shortening of duration training as well as reduction of working hours in the United Kingdom has led to obstetric trainees being less experienced in conducting instrumental deliveries. Thus, many junior trainees may prefer to conduct relatively uncomplicated instrumental deliveries in theatre. Appropriate training and senior staff input would help reduce this.