Comparison of perinatal outcomes for all modes of second stage
delivery in obstetric theatres: a retrospective observational
study
Leo Gurney1, Bassal H Al Wattar2,
Ali Sher3, Carlos Echevarria4, Helen
Simpson3
1 West Midlands Fetal Medicine Centre, Birmingham Women’s and Children’s
NHS Foundation Trust, Birmingham, UK
2 Warwick Medical School, University of Warwick, Coventry, UK
3 Maternity department, James Cook University Hospital, Marton Road,
Middlesbrough, UK
4 Respiratory department, Royal Victoria Infirmary, Newcastle Upon Tyne
Running title: Perinatal outcomes for second stage delivery
Abstract
Objective
To compare rates of vaginal delivery and adverse outcomes of
instrumental delivery trials in obstetric theatre compared to primary
emergency full dilatation Caesarean section
Design
Retrospective cohort study
Setting
University teaching hospital
Population
Women with singleton, non-anomalous, pregnancy undergoing instrumental
delivery trial in obstetric theatre
Methods
Data was collected from consecutive cases during 2014 until 2018 using
clinical records. Multivariate regression analysis was used comparing
groups per first delivery attempt.
Main Outcome Measures
Primary outcome was completion of vaginal delivery between all methods
of instrumental delivery. Secondary outcome was a composite of immediate
perinatal adverse outcomes for instrumental delivery modes and primary
full dilatation Caesarean section.
Results
From 971 deliveries analysed: ventouse delivery was significantly less
likely to achieve vaginal delivery compared to Keilland’s forceps
delivery (OR 0.42, 95%CI 0.22-0.79). Once confounding factors were
adjusted for, adverse outcome rates were less frequent in the Keilland’s
forceps group compared with primary full dilatation Caesarean section
(OR 0.37, 95% CI: 0.16-0.81), however the receiver operating
characteristic curve produced from this model demonstrated low
predictive value (AUC 0.64).
Conclusions
Attempting instrumental delivery in delivery suite theatre, as an
alternative to primary emergency full dilatation Caesarean section, is
both reasonable and safe. Ventouse delivery in this situation may be
associated with a higher chance of failure than other modes of
instrumental delivery, thus making appropriate choice of delivery method
of paramount importance according to each clinical situation.
Funding
None
Keywords
Caesarean section, Keilland’s forceps, ventouse, trial of instrumental
delivery
Tweetable abstract
Instrumental delivery trials in theatre
are safe but use of ventouse associated with higher rate of failure.
Introduction
Rates of Caesarean section are increasing progressively; a trend
observed in both developed and developing countries 1.
As well as exposing women and babies to immediate surgical risks, a
Caesarean section will characterise any subsequent pregnancy as higher
risk: conveying on the mother novel pregnancy risks including
complications such as placenta accreta or uterine scar rupture, and
leading to a need for increased resources to manage such pregnancies2. Several health authorities including the World
Health Organisation and medical colleges have prioritised efforts to
reduce the rate of unnecessary Caesarean section and resulting harm to
mothers 3, 4.
The use of instruments to aid vaginal delivery in the second stage of
labour is common practice in many countries. Reasons for this include: a
failure for birth to occur promptly, concern regarding fetal distress,
maternal request for assistance or a need to shorten the second stage
due to maternal illness 5. A patient will be
transferred from delivery suite room to obstetric theatre for a ‘trial
of instrumental delivery’ if a more challenging delivery is anticipated,
common reasons for transfer including fetal malposition, maternal
obesity, or to optimise maternal analgesia 6.
Clinicians must choose the most appropriate method of delivery from the
options of: Keilland’s rotational forceps delivery (KFD), direct forceps
delivery (DFD), initial rotation of a baby manually followed by
non-rotational forceps delivery (MR+FD) or ventouse delivery (VD). If
instrumental delivery is not deemed suitable or is unsuccessful, then
recourse to delivery by primary emergency full dilatation Caesarean
(pEmCS) section is required 7.
Internationally, rates of instrumental deliveries are declining due to
concerns regarding associated complications such as neonatal injury or
maternal perineal trauma, a decrease that becomes self-perpetuating as
clinicians become less familiar and confident to perform such deliveries8. As a corollary, primary full dilatation Caesarean
sections are increasing 9; however, such deliveries
are associated with high rates of maternal and neonatal morbidity10 , and can increase the risk of preterm birth in a
subsequent pregnancy 11.
Observational studies comparing outcomes of instrumental delivery in
obstetric theatre have demonstrated that Keilland’s forceps delivery may
be associated with an increased chance of successful vaginal delivery
compared to other forms of instrumentation without a significant
increase in exposure to maternal or neonatal risks12-14. However, data is limited comparing immediate
perinatal adverse outcomes from all four instrumental delivery types and
many studies do not include primary emergency Caesarean section as a
control group.
This study aimed to address this deficit by examining all obstetric
theatre trials of second stage delivery over a 5-year period, in a
university teaching hospital where all methods of instrumental delivery
are routinely practised. The primary objective was to examine completion
rates of vaginal delivery between all four forms of instrumental
delivery (KFD, DFD, MR+FD, VD), taking possible confounding factors into
account. The secondary objective was to compare immediate perinatal
adverse outcomes between instrumental delivery groups and the pEmCS
group.
Methods