Intermittent auscultation (surveillance) of fetal heart rate in labor: a progressive evidence-backed approach with aim to improve methodology, reliability and safety

Abstract

Intermittent auscultation (IA) of fetal heart has become acceptable in low risk labors even in the developed countries. However, the instances of birth asphyxia occur despite adhering to the guidelines. Such outcomes need not be the inherent limitations of IA, but improvements in the IA regime are highly desirable. The systematic analyses of available studies have been unhelpful to ascertain an optimal regime or suggest improvements. This analytical review uses detailed modeling and reasoning to examine/propose safe and effective regime. It counters a misconception that the Doppler-device is not superior to Pinard stethoscope in usability, accuracy and thereby decision making. Importantly, the Doppler-device should not be used to actually count the fetal heart tones (like a Pinard stethoscope) as insisted by many guidelines. The review demonstrates that counting to 120–160 over a minute is arduous, superfluous and fraught with fallacies and risks. Observation of the digital read-out of the fetal heart rate (FHR) and its trend during the auscultation duration is far more informative. IA should focus on the two FHR parameters namely the baseline and late decelerations. Detection of additional FHR changes like overshoots, cycling or accelerations do not add value. Doppler-device FHR readouts over a steady pattern (commonly just before the contraction) best represent the baseline. FHR observation (IA) should commence in the later part of the contraction and continue till the beginning of next contraction and need not arbitrarily end at 1 min (a legacy of preoccupation with actual counting). Heightened awareness is required to detect late decelerations at the end of contractions. It would suffice to perform IA over a couple of contractions every 20–30 min during the first stage of labor. This improved methodology would avoid mistakes and improve the detection of FHR abnormalities to enhance patient safety in future practice guidelines.

Keywords:

• Intrapartum fetal monitoring
• intermittent auscultation
• late decelerations
• Doppler fetal heart rate monitor
• Pinard stethoscope

Acknowledgements

The author is grateful to the midwives in his institute and other hospitals who have always showed keen interest and willingness to participate in studies sharing their wisdom and experience in IA and CTG.

Contribution to authorship

The author conceived the review, performed the literature search and wrote the contents.

Disclosure statement

The author has no conflict of interest or funding to declare. The article is based on author’s hands-on experience of IA for 8 years, followed by experience in CTG for 25 years.