INTRODUCTION
During the active second stage of labour, operative deliveries may be
indicated for fetal distress or dystocia1.
Obstetricians need to choose between an immediate caesarean section
(C-section) and an attempt at operative vaginal delivery (OVD), which
has an estimated failure risk from three to seven
percent2–6.
The American College of Obstetricians and Gynecologists (ACOG) and the
Society for Maternal-Fetal Medicine consider that OVDs performed by
experienced operators are safe and acceptable alternatives to
C-sections2. Mid-cavity OVDs are associated with more
birth and obstetric trauma than low-cavity OVDs and
C-sections7–10. Nevertheless, the ACOG and the Royal
College of Obstetricians and Gynaecologists (RCOG) consider that
mid-cavity OVD performed by experienced operators can be reasonable in
selected cases. The French College of Gynaecologists and Obstetricians
considers that the available scientific data are insufficient to
contraindicate it2,10-13.
The majority of OVDs are conducted in classical delivery
rooms14. According to the RCOG, mid-cavity OVDs have a
higher failure risk. They should therefore be considered as a trial and
conducted in a place where an immediate C-section could be
undertaken10,13. A trial in an operating theatre could
reduce the delay between failed OVD and C-section and thus reduce
neonatal morbidity. However, in the case of a successful OVD, the delay
associated with transfer to the theatre may worsen neonatal
outcomes10,13. As specified in a Cochrane Review, the
transfer decision is subjective, and no current evidence can influence
the practice of mid-cavity OVDs14.
Vacuum use has recently increased: the vacuum is now the most used
instrument, particularly in Europe and in the United
States15–18.
Risk factors for failed OVDs are well described and include a high
station of the fetal head3,4,6,10,
primiparity5, macrosomia3–6,10,
prolonged labour5,19, high maternal
weight10,19, labour induction5,19,
prolonged pregnancy3, and the occiput-posterior
position3,5,6,10. A score comprising these different
factors could help obstetricians select women with a high failure risk,
for whom an attempt at mid-cavity OVD should be conducted in the
theatre, with additional precautions: anticipated extension of epidural
analgesia and concomitant preparations of C-section equipment.
The principal objective was to identify risk factors strongly associated
with failed mid-cavity vacuum-assisted delivery (VAD) and to construct a
risk model that could be used to guide obstetricians in choosing between
a standard delivery room or an operating theatre.
The secondary objective was to compare maternal and neonatal outcomes
according to the place and the conditions of the VAD
attempt.