Intermittent Auscultation or Intermittent FHR surveillance?
The question may sound strange. IA is an old term when fetal heart rate (FHR) could only be listened to and counted with stethoscope. Moreover, the very early hand-held Doppler-devices produced only audible tones but no numerical readout of FHR. But for the last 25 years the Doppler-devices continuously display the instantaneous FHR as beats per minute. Hence, this very basic facility means that it is not a must to actually count the fetal heart tones anymore, even if or just because we continue to use the old term ‘auscultation’. Is it really worth changing the terminology of IA to something like ‘intermittent FHR surveillance/observation’? Thus, the idea that IA must involve the skill in listening and actually counting sounds9,10 is out-dated and best discarded. For example, a proposed ‘intelligent IA’ states, “In conclusion, the recommendation should be to listen for at least a full minute and count the baseline, the steady rate, but listen for accelerations and decelerations.” A bit of detailed consideration reveals this foundational recommendation to be full of contradictions (hence void). If one actually counts for one minute, it is not possible to know in advance whether one is starting with a late deceleration or one is going to encounter an acceleration. Moreover, after ‘listening’ to a deceleration or acceleration, only a part of the one minute (not counted separately) would be the ‘steady rate i.e. the baseline’. Then one has not really counted the steady rate separately at all but only the average rate over the full one minute (including the acceleration/deceleration). Extending beyond one minute would require restarting the count from zero again and deciding when to stop counting (when will one be satisfied that one has managed to count the steady the steady rate separately, how?). It is far more accurate, reliable and convenient to simply watch the FHR numerical display on the Doppler-device and observe the FHR figure accelerate or decelerate (approximately how much as well) or remain steady during the entire or part of the duration of auscultation (a minute or flexibly more as much as required).6 One can decide which part of the observation showed the steady FHR most likely to represent the baseline. In presence of late decelerations or accelerations, the baseline rate is likely to be observed a bit before or during early part of the contraction.6 Many guidelines (wrongly) persist with the preoccupation of actually counting the fetal heart tones1,2; while the WHO guidelines11ambiguously mention, “Each auscultation should last at least 1 minute; if the FHR is not always in the normal range (I.e. 110-160bpm), auscultation should be prolonged to at least three contractions.” Clearly, the paradox is that one can confirm FHR to be always in the 110-160 range during the auscultation period only by looking at the actual numerical FHR display on the Doppler-device or by a complicated ‘multiple count strategy’4 but not at all by simply counting the fetal heart tones for 1 minute or more.