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Cochrane Database of Systematic
Reviews 2006 Issue 3
Types of studies
Published and unpublished
randomized trials comparing fetal biophysical profile (scoring system derived
from B-mode ultrasound monitoring of fetal movements, tone and breathing,
ultrasound assessment of amniotic fluid volume, and electronic fetal heart rate
monitoring) with other forms of antepartum fetal assessment. We anticipated
that early trials may not have used strictly random allocation and, therefore,
we planned to include trials that used a quasi-randomized method of treatment allocation
such as alternation by hospital number or woman's date of birth.
Types of participants
Women with high-risk pregnancies (hypertension, intrauterine growth
retardation, post-term, diabetes, previous stillbirth, decreased fetal
movements, antepartum haemorrhage, premature labour, Rhesus disease).
Results
When compared with conventional fetal monitoring (usually cardiotocography)
biophysical profile testing showed no obvious effect (either beneficial or
deleterious) on pregnancy outcome. There was an increase in the number of
inductions of labour following biophysical profile in the Alfirevic 1995 trial.
(If CTG has already been shown to be unreliable,
then we are really left with no method to reassure us baby is o.k. No wonder
the medical profession is nervous MM).
Discussion
Available evidence from randomized controlled
trials provides no support for the use of biophysical profile as a test of
fetal well-being in high risk pregnancies. However, the total number
of women included in this meta-analysis is only 2,839. This is a very small
number bearing in mind that overall incidence of adverse outcomes was so low
(perinatal deaths = 0.8%; low Apgar score = 2.4%); thus, one could not assume
that the biophysical profile is without value. For example, to make any
meaningful conclusion about the impact of the biophysical profile on perinatal
mortality in excess of 10,000 women would need to be studied. Furthermore, the
impact of the biophysical profile on obstetric interventions, length of
hospitalisation, serious neonatal morbidity and parents satisfaction are
virtually untested. (Looks
like it is under researched)
The increase in inductions of labour observed in the small trial by Alfirevic
and Walkinshaw (Alfirevic 1995) highlights the need for careful evaluation of
the impact of different fetal monitoring policies on a much wider range of
relevant outcomes. The observed increase in inductions in this study was
thought to be caused by the difference in the type of test used to assess
amniotic fluid volume in two groups (amniotic fluid index in the biophysical
group and maximum pool depth in the control group) rather than by the
biophysical profile itself. The amniotic fluid index was more frequently
abnormal than maximum pool depth leading to more obstetric interventions in the
biophysical profile group.
