METHODS
We conducted an observational analytical predictive prospective
monocentric study of attempts at mid-cavity VAD performed between
January 2010 and December 2018 in the Maternity Unit of the University
Hospital of Besançon, France.
All attempts at mid-cavity VAD with epidural analgesia, after 37 weeks
of gestation, in singleton pregnancy with a vertex presentation were
included. The mid-cavity was defined as a fetal head that was no more
than one-fifth palpable per the abdomen and a leading point of the skull
above station plus two centimetres but not above the ischial
spines10,13. In our study, this corresponded to a
head-perineum distance measured by trans-perineal ultrasound that was
greater than or equal to 40 mm at the beginning of the VAD, without
compression of the soft tissue against the pubic bone, as described by
Maticot-Baptista et al. and ISUOG20,21. We also
included the few high-cavity VADs defined by head-perineum distances
greater than 60 mm.
The safety conditions for performing a mid-cavity VAD were strict and
corresponded to our usual practices: performance of the VAD by a senior
obstetrician, with preliminary ultrasound verification of the fetal head
position and station, with placement of appropriate analgesia, alerting
of the anaesthetist and paediatrician, informing the woman of the
possibility of failure, and obtaining her verbal consent. The
obstetrician decided on the conditions of the VAD attempt: type of room
and eventual concomitant preparation of C-section equipment. The
eventual anticipated extension of epidural anaesthesia was either
requested by the obstetrician or decided by the
anaesthetist to reduce the
incision delay in case of C-section. It corresponded to a first epidural
top-up administered during the preparation or the realization of the VAD
before the potential decision of C-section: clonidine 50 to 75 µg and/or
lidocaine 2 % 5 cc and/or sufentanil 5 to 10 µg, depending on the
anaesthetist’s preference. In case of failed VAD, a second top-up was
administered just after the C-section decision. In case of failed VAD in
a classical delivery room, women were transferred to the surgical room
for the C-section.
Both successful and failed attempts leading to an emergency C-section
were included. Sequential uses of instruments (failed VAD followed by
successful spatula- or forceps-assisted delivery) were considered
successful attempts.
The study was approved by a local ethical committee (Comité de
Protection des Personnes Est II) and by the French data protection
agency (CNIL: Commission nationale de l’informatique et des libertés)
under report number 2051119v0. The study was registred on
ClinicalTrials.gov (identifier: NCT03853499).
No specific funding was received for this study.