Introduction
Intermittent auscultation (IA) of fetal heart rate (FHR) is approved for
fetal monitoring in low-risk labours in most developed
countries.1-4 In the UK it is expected that up to 50%
of women may have IA.1 However, IA as well as
cardiotocography (CTG) are often criticized as ‘evidence free zones.’
Consequently, a small number of sceptics demand abandonment of CTG
itself, 5 not a practical prospect for very good/valid
reasons. There are many more detractors of IA (personal communications)
who question the few randomised controlled trial (RCTs) showing
equivalent outcomes with IA and CTG. The gold standard of evidence in
medicine remains RCTs. But, very large studies required for definitive
guidance for IA are unlikely to come. As a result, there has been
proliferation of several different regimes of IA.1-4Instances of serious intrapartum asphyxia continue to occur despite
complying with the recommended regimes 6 highlighting
the scope and need for improvements. A recent comprehensive systematic
review of 26 studies and 11 guidelines concluded that the optimal regime
of IA (frequency, duration, method) remains unproven.7Similarly, many other systematic analyses have failed to provide
practical suggestions for improvement.6
Empiricism remains at the heart of science and statistics is said to be
its grammar. Interestingly, ‘thought experiments’ have contributed to
many major advances, not just in physics. Critical thinking is now
considered at least as important as the statistical
tests.8 This review is not based on anecdotes but
evaluates IA regimes and possible improvements by detailed modelling and
reasoning, consistent with methods adopted in many consensus
guidelines.1-4 Any evidence when available is
supplemented with experience and observational knowledge gained from
CTG. The focus is on the actual method of IA only. Other aspects of IA
are outside the remit. Some of the discussion may appear very simple,
obvious and intuitive, but still needs to be presented for reflection
and bringing about practical improvements.