Mayday 1C: Auscultation ~ traditional & scientifically-validated way to listen to FHR

by faithgibson on May 1, 2019

in Economic Issue$, Electronic Fetal Monitoring

Auscultation (also known as hands-on listening) is a non-continuous method used since the early 20th century to monitor fetal well-being (i.e. the verb, not the machine) during active labor.

A physician, midwife or L&D nurse uses a fetoscope or hand-held Doppler to regularly listens to the fetal heart rate and rhythm and record the information on the mother’s chart.

Studies on the efficacy of electronic fetal monitoring are always contrasted to the outcomes of auscultation. While the word ‘auscultation’ often does not appear in the same sentence as the study’s conclusion, nonetheless the comparison is always between EFM and auscultation, not between monitoring with EFM versus no monitoring

The Science-based Standard for Healthy Women with low-risk pregnancies is not EFM

Hands-on auscultation is the “control” against which all studies on the efficacy and effectiveness is EFM is measured.  When reading studies that found no benefit to c-EFM, that finding validated auscultation as having equal or better outcomes.

Based on this scientific evidence, auscultation is the preferred standard of care during the active stages of labor for women with normal pregnancies. Auscultation, or ‘hands-on’ monitoring, is already is a routine part of the care provided by midwives and some family physician birth attendants.

Using a fetoscope or hand-held Doppler, the L&D nurse or other professional birth attendant regularly listens to the fetal heart every 30, 15 or 5 minutes, a frequency that depends on the stage of labor and baby’s response to long and strong contractions.

By counting the heart rate for one full minute (or longer, but never shorter), the ‘beats per minute’ heart rate (bpm) and its rhythm (regular, irregular, with or w/o accelerations and with or w/o decelerations) are identified and recorded on the mother’s labor chart.

Auscultation uses the same four parameters of information for determining fetal well-being first taught by Dr. Joseph DeLee in the 1920s and still used today for interpreting c-EFM strips.

The standard for fetal wellbeing is determined by the presence of:

    • a normal baseline
    • normal variability
    • normal accelerations
    • no pathological decelerations
  • The normalcy of the FH rate and rhythm  relative to these four factors is used to determine if a ‘reassuring’ pattern is, or isn’t, present.

This same auscultation criteria is consistent with the current systematic approach to interpreting the electronic fetal monitor tracing. In 2008, the National Institute of Child Health and Human Development (NICHHD) convened a workshop to revise the accepted definitions for electronic fetal monitor tracing and introduce a new classification scheme for decision-making with regard to EFM tracings. However, this on-going assessment model both reflects and applies to auscultation as well.

The NICHHD task force identified the key elements for assessing fetal wellbeing in EFM to be the same ones used in auscultation:

(1) baseline heart rate
(2) presence or absence of variability
(3) interpretation of periodic changes

This system also conforms to the Advanced Life Support in Obstetrics course mnemonic: DR C BRAVADO as a memory tool for the systematic interpretation of fetal monitoring data.

DR = Determine Risk, which refers to the ongoing assessment of both maternal and fetal risk factors each time the FHR is monitored. 

C = Maternal Contractions, the status of which is constantly factored into the birth attendant’s on-going determination of risk. For example, a modest FHR deceleration during a long, strong pushing contraction would be considered normal, whereas the same type of deceleration during latent labor would not be considered normal.   

Fetal monitor strip/FHR via auscultation: BRAVD
B = baseline rate, V = variability, A = accelerations, and D = decelerations

O = overall assessment and interpretation of fetal wellbeing (or lack thereof) 

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