Fetal heart rate monitoring Flashcards
late decels
characteristics, likely cause, and mgmt
characteristics
>15bpm drop lasting 15sec ( or <15bpm drop, if also reduced variability (<5bpm)
>uniform/ repetitive
»slow onset from mid to end of contraction, lowest point is >20sec after peak of cx contraction started, recovers after Cx finished
likely cause
hypoxia (the longer the late decel, the worse)
management
Consult
what is a prolonged decel
Drop in baseline FHR >90 sec - 5min
what are reasons for reduced variability
fetus sleeping (most common- but shouldn’t be for longer than 40mins)
fetal acidosis (due to hypoxia) –more likely if there are also late decels
fetal tachycardia
drugs- opiates, mg sulphate
preterm
congenital heart abnormalities
variable decels
characteristics
repetitive or intermittant depth / duration
usually with a contraction- typically rapid onset and recovery
- may / may not have shouldering
likely cause
with shouldering- normal physiological response- cord compression
if no shouldering- could indicate fetus becoming hypoxic
mgmt
assess for any “ complicated features-“
if no complicated features, generally assume baby is having eustress and coping ok
if variable decels are persistent consider changing position / more monitoring
complicated variable decels
features that indicate liklihood of fetal hypoxia
- rising baseline or fetal tachycardia
- reducing baseline variability
-slow return to baseline after cx - large amplitude of decel i.e. drop by 60bpm, or to 60bom, or lasting longer than 1min
- presence of smooth post decel overshoots
what is shouldering?
What does it indicate
HR accelerates at start of cx, then rapidly decelerates, then rapidly accelerates.
Presence indicates fetus is not hypoxic and adapting to reduced blood flow (usually cord compression)
definition of deceleration
abrupt decrease in FHR baseline >15bpm for >15 sec
CTG - definition of normal baseline variability
“minor fluctuations in baseline FHR- occur 3-5cycles / min
6-25bpm
‘reassuring baseline’ is >5
Definition of acceleration
> 15bpm increase in baseline, lasting >15 sec
Normal and reassuring to have accelerations (although unclear whether there is an issue if there is absence of accelerations )
preterm accelerations smaller
What is a sinusoidal CTG pattern
indicators:
smooth wave like pattern, 2-5 cycle / min
no accels/ decels in 20mins
no variability
Indication
severe fetal hypoxia or anaemia, maternal or fetal haemorrhage
CONSULT
what is management of abnormal CTG
? Checking maternal pulse/attach maternal probe if not recorded by toco
? Checking positioning of CTG transducer
? Maternal position change to increase utero-placental perfusion and/or alleviate cord
compression
? Continuing or commencing continuous EFM
? Identification of any reversible cause of the abnormality and initiation of appropriate action
(e.g. correction of maternal hypotension, cessation of oxytocin infusion* and/or acute tocolysis
for excessive uterine activity)
? Consideration of fetal blood sampling
? Escalation of care
what is a bradycardia
what does this mean
fall in FHR baseline for >5mins
LIKELY to be associated with significant fetal compromise
IMMEDIATE management
what is a normal reassuring CTG
Baseline btn 110-160
variability present (6-25)
2 accelerations in 10-20mins (>15bpm, for >15sec)
no decels
what is most important aspect of CTG
variability –> fluctuating 5-25bpm over 10-20 sec
what is increased variability?
> 25
what is reduced variability
3-5bpm
what is absent variability
<3 bpm
how do we identify baseline FHR
rate in absence of both movements + cx
how do we define baseline bradycardia- what are possible reasons?
<100bpm, lasting >10mins
reasons
hypoxia
drugs
congenital
hypotehermia
how do we define tachycardia - what are possible reasons?
> 160bpm for more than 10mins
maternal fever
fetal infection
hypoxia
prem babies (<34wks) - normal
when can you use Dawes redman
Antenatal only- NOT intrapartum
Early decels -
characteristics, likely cause, and mgmt
characteristics
15bpm drop, for 15 sec
uniform / repetitive
slow early onset in cx, slow return to bsaeline by end of cx
Likely cause
head compression, pethadine, sleep trace
how do we interpret this
- this classifies as “non reassuring / “suspicious” / “abnormal but unlikely to be compromising”)
uterine hypertonus / hypersystole
cx lasting >2mins
or cx occuring within 60seconds of each other
without FHR ABNORMALITY
uterine hyperstimulation
definition
referral
mgmt
either uterine tachysystole (>5cx:10) or hypertonus (>2mins or <60sec rest between)
AND FHR abnormalities
Referral
CONSULT
mgmt
- Reduce / cease oxytocin
- continuous monitoring / stay with woman
- consider tocolytic + urgent delivery
uterine tachysystole
> 5 contractions in 10mins
without FHR abnormalities
when is Dawes- Redman appropriate
> 28 wks
AN only (not intrapartum)
when can you start using continuous CTG
> 26 wks
what is moderate bradycardia, what is abnormal bradycardia?
moderate-100-109bpm
abnormal <100bpm
what is moderate tachycardia?
what is abnormal tachycardia
moderate: 160-180bpm
abnormal >180bpm
intermittant auscultation
protocol
1st stage-
every 15-30mins
listen for at least 1min
record as single rate, and any accelerations /decels heard
2nd stage
every 5mins (or every cx)
listen for 30-60 sec from end of cx
listen to maternal pulse hourly (at least)
What are risks associated with fetal scalp electrodes
what are contraindications
bruising / scratching baby’s scalp
risk of infection to mum / baby, or from mum to baby
contraindicated- HIV, herpes, hepatitis
what does the evidence say about CTG use in low/high risk pregnancy
CTG associated with
* signficiant decrease in neonatal seizures
* increase of CS / operative birth
* no difference in perinatal death / cerebral palsy
NOT recommended for low risk women
what is normal preterm baseline
higher than term
what is normal baseline for post term fetus
90-100 bpm (as parasympathetic system is maturing)
