Key content
Oxytocin is a well-established drug with a long history of use.
The generation of intrauterine pressure is a result of myometrial
activity, but is attenuated by a softening cervix.
The introduction of active management regimens have not
changed the outcome of labour as we envisaged.
Too many babies suffer asphyxia as a result of misuse of oxytocin.
Some form of education programme must be developed to warn of
the dangers of this very useful drug.
Better training and education programmes must be in place for
midwives and obstetricians for labour management and
cardiotography interpretation.
Learning objectives
To outline the history of the development of oxytocin.
To understand the mechanism of intrauterine
pressure development.
To understand the methods of intrauterine pressure measurement
and assessment.
To understand the development of principles of active
management with a discussion of the subsequent studies analysing
the results of such labour management.
To outline the medicolegal aspects of labour augmentation, with
particular reference to oxytocin use.
To discuss possible implications for the future.
Ethical issues
Should all women be given the information that oxytocin
augmentation of slow labour may reduce the duration of labour by
several hours but does not change the mode of delivery, whilst
carrying a risk of causing fetal asphyxia?
Should women sign informed consent before their labours
are augmented?
Should augmentation of labour only be undertaken under the
direct supervision of a senior clinician?
Keywords: active management / augmentation / labour /
medicolegal / oxytocin / uterine activity
Introduction
Measurement of uterine activity
Tachysystole or hysperstimulation
Oxytocin regimens: active management
Cochrane reviews
A 2013 Cochrane review24 of studies relating to the use of
oxytocin for the treatment of ‘slow labour’ reviewed eight
studies involving 1338 low-risk women in the first stage of
spontaneous labour at term. In this review, oxytocin did not
reduce the need for caesarean sections or forceps deliveries,
and neither did it increase the number of vaginal deliveries
when compared with no treatment or delayed oxytocin
treatment. Oxytocin did shorten labour, but only by 1.3
hours on average. However, in this review, it did not seem to cause harm to the mother or baby, although the sample size
was too small to determine if its use had an effect on
perinatal mortality.
The future
Oxytocin is a useful drug. Its use is essential in many cases to
induce labour, and with it we can control the contractility of
the uterus. However, it is also a dangerous drug. Before we
use it in cases of slow labour we need to consider potential
causes other than poor uterine activity, for example, a full
bladder, a cervix that needs time to ripen, malposition of the
fetal head, even occasionally disproportion (increasingly seen
with macrosomia); and the implications of artificially
increasing uterine contractility.
Consideration needs to be given to whether the cervix is
tightly closed, whether there is a uterine scar and whether the
CTG is normal. Most of the issues surrounding the
medicolegal cases are multifactorial. Misinterpretation of
fetal heart rate monitoring combined with increasing doses of
oxytocin is a common finding in cases of fetal demise or
acidaemia. The failure to recognise hypertonicity/tachysystole
as a consequence of increasing doses of oxytocin is also
something that continues to occur with depressing regularity So what can be done to improve the situation? As
professional groups, doctors and midwives should be
certified to have been on a proper CTG interpretation
training course. This should be a thorough training course
and not a single lecture. They should also have been
appropriately assessed as being capable of recognising the
majority of CTG abnormalities. Such a course should include
information on the physiology of uterine activity, the use of
oxytocin and the principles of labour management, perhaps
emphasising the primary importance of one-to-one care.
Training (including reassessment of ability) should be
repeated at regular intervals, perhaps annually. What is
clear is that if we continue to use oxytocin as we currently do
we will continue to cause fetal asphyxia and fetal death with
all the consequences that entails.