What FHR abnormalities should IA detect?
It is important to remember that the main asset of IA is its
“simplicity” arising from the deliberate intention to detect a limited
number of most important FHR abnormalities in low risk cases. This also
accounts for its advantage over CTG namely lower medical/operative
intervention. Occam’s Razor (law of parsimony) is a well-established
scientific principle implying that (unnecessary) complexity burdens
practitioners of science reducing validity and
performance.12,13 Clinicians facing complex
multi-faceted problems need to make optimum use of their attention
‘bandwidth’ to minimise errors and facilitate appropriate timely
decisions. Midwives need to be able to devote more time and attention to
broader holistic care to normal women in low risk labours. Hence, the
safe practice of IA stemming mainly from the British obstetrics aimed to
detect the two most important FHR parameters namely the baseline and
late decelerations, as the latter generally have the most significant
correlation with fetal hypoxemia/acidemia.1 This has
been the reason for traditional recommendation of FHR auscultation for 1
minute immediately after a uterine contraction.1-3 The
detailed information/accuracy gained from CTG cannot be expected from IA
and indeed seems unnecessary at least in low risk cases as a pragmatic
compromise.1-4,6 There is good agreement that IA is
not expected to detect baseline FHR variability.1-4Descriptions like ‘timber, strength and cadence’ of fetal heart sounds7 with Pinard stethoscope (or Doppler-device) have
been rightly confined to the history. Significant rhythm irregularities
easily heard are obvious exception. Specific detailed explanation about
how to detect the two abnormalities by IA guidelines would bestow added
confidence and assurance to the nurse-midwives.