Doppler-device versus Pinard stethoscope: Evidence from RCTs
In addition to the practically perceived accuracy, the hand-held
Doppler-device has additional advantages of ease, simplicity and
reassurance to the mother of hearing the fetal heart sounds. Why do then
guidelines 1-4,11 maintain that that the
Doppler-device or Pinard are equally preferable? Indeed, a systematic
scoping review of many aspects of IA was unhelpful for practice
improvement but highlighted only one conclusion namely
“there was no evidence to
recommend Doppler-device instead of Pinard”.7 But is
this sole conclusion valid? Is the evidence judiciously interpreted and
then appropriately applied? Does statistics often leads scientists to
deny differences that are clear to see or
experience?8,19
There are four RCTs of “Doppler vs Pinard” including 8436 women, all
from African countries.7,20-23 In three studies the
facility of CTG was not available/used at all.20-22 In
contrast, CTG is the recommended recourse after abnormal IA in developed
countries to optimise perinatal outcome.1-4 Only one
study 23 from a teaching university hospital had CTG
facility available (for a separate group); but it appears that the
Doppler and Pinard groups did not have CTG after detection of
abnormalities on IA. The perinatal outcome was much worse in the Pinard
than in the Doppler group (neonatal convulsions 6 vs 0, hypoxic
encephalopathy 7 vs 1, perinatal mortality 5 vs 2), but the differences
were not statistically significant due to small patient numbers (312 and
310) in the two groups.23 Most importantly all four
study protocols only required detection of FHR baseline in the abnormal
range (<120 or >160 beats/minute); but the
detection of late decelerations was not
required/advised.20-23 This was indeed the standard
recommendation by the World Health Organisation (WHO) when these RCTs
were performed.24 This recommendation has only
recently been upgraded by the WHO 11 to include
decelerations thus making these RCTs 20-23 outmoded.
The main perceptible advantage of Doppler-device is the improved
detection of FHR decelerations. Thus, for reasons above it can be
concluded that the results from these African RCTs7,20-23 cannot be extrapolated to the obstetric
practice in developed countries.