Introduction A Cardiotocograph (CTG) is a record of the fetal
heart rate (FHR) either measured from a transducer on the abdomen
or a probe on the fetal scalp. In addition to the fetal heart rate
another transducer measures the uterine contractions over the
fundus
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Abbreviation: CTG = Cardiotocograph What does "Cardiotocograph"
mean? Cardio = heart Toco = contractions (of uterus during labour)
Graph = machine to record Cardiotocograph = machine to record the
heart rate (fetal heart) and contractions of uterus during
labour
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Physiology During labour the fetus can become stressed. The
heart rate of the fetus is monitored throughout labour so stress
can be detected early. The contractions are monitored also so that
the midwife and mother know when the contraction is occurring and
also to check for fetal distress during the contraction.
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Units of measurement Fetal heart rate: BPM (beats per minute)
Contractions: contractions\ 10 minutes. IUP: mmHg
Interpretation The CTG trace generally shows two lines. The
upper line is a record of the fetal heart rate in beats per minute.
The lower line is a recording of uterine contractions from the
toco. The trace may also have markings on it that are indications
that the mother has felt a fetal movement (operated by a switch
given to the mother)
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Baseline Rate This should be between 100 and 160 beats per
minute (BPM) and is indicated by the FHR when stable (with
accelerations and decelerations absent). It should be taken over a
period of 5 - 10 minutes. The rate may change over a period of time
but normally remains fairly constant.
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Bradycardia This is defined as a baseline heart rate of less
than 110 bpm. If between 110 and 100 it is suspicious whereas below
100 it is pathological. A steep sustained decrease in rate is
indicative of fetal distress and if the cause cannot be reversed
the fetus should be delivered
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Tachycardia A suspicious tachycardia is defined as being
between 160 and 170 whereas a pathological pattern is above 170.
Tachycardias can be indicative of fever or fetal infection and
occasionally fetal distress (with other abnormalities). An epidural
may also induce a tachycardia in the fetus
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Baseline variations The short term variations in the baseline
should be between 10 and 15 bpm (except during intervals of fetal
sleep which should be no longer than 60 minutes). Prolonged reduced
variability along with other abnormalities may be indicative of
fetal distress
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Accelerations This is defined as a transient increase in heart
rate of greater than 15 bpm for at least 15 seconds. Two
accelerations in 20 minutes is considered a reactive trace.
Accelerations are a good sign as they show fetal responsiveness and
the integrity of the mechanisms controlling the heart
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Decelerations These may either be normal or pathological. Early
decelerations occur at the same time as uterine contractions and
are usually due to fetal head compression and therefore occur in
first and second stage labour with decent of the head. They are
normally perfectly benign. Late decelerations persist after the
contraction has finished and suggest fetal distress.
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A normal CTG is a good sign but a poor CTG does not always
suggest fetal distress. A more definitive diagnosis may be made
from fetal blood sampling but if this is not possible or there is
an acute situation (such as a prolonged bradycardia) intervention
may be indicated
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Uterine contractions monitoring Count the number of
contractions to determine the pattern of uterine contractions is it
normal, hypoactive, or hyperactive. Normal number of contractions
3-4 contractions \10 min. Determine the strength of the
contractions (IUP) as apeare in the trace by mmHg.
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Nursing Interventions if Uterine Hyperstimulation or Fetal
Distress Occur: RationalInterventions 1-To improve fetal-placental
blood flow. 1-Turn woman on her left side. 2-To provide adequate
intravascular volume, support maternal BP, and I.V route for
emergency medications. 2-Increase primary I.V rate up to 200 ml/hr
unless contraindicated.
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Continue RationalInterventions 3-To saturate the blood with
oxygen as much as possible to prevent fetal anoxia. 3-Give oxygen 6
to 10 l/min ( per protocol) by face mask. 4-This indicate induction
failed. If membrane intact discontinue induction and try again
later. If membrane ruptured cesarean birth may be necessary.
4-Notify doctor