Fetal Monitoring Flashcards
causes of adverse fetal neonatal outcomes
antepartum complications
suboptimal uterine perfusion
placental dysfunction
intrapartum events
why is fetal heart monitoring so important?
early recognition of changes in FHR can serve as a warning to physician to intervene and prevent irreversible brain injury or death
external monitoring for uncomplicated pregnancy
q30 minutes in active phase of stage 1
q15 minutes in stage 2
external monitoring for complicated preganancy
q15 minutes in active phase of stage 1
q5 minutes in stage 2
what provides the most accurate FHR tracings?
internal monitoring
components of external fetal monitoring
doppler ultrasound overlying the fetal heart
pressure-sensitive tocodynamometer - records contractions
components of internal fetal monitoring
fetal scalp electrode
intrauterine pressure catheter
what happens to placental exchange of gases during contraction?
temporarily stops due to:
compression of uterine myometrial vessels
compression of umbilical cord
compression of fetal head
how long can a fetus last without oxygen?
1-2 minutes due to fetal oxygen reserve
what is the result of severe fetal hypoxia
anaerobic metabolism resulting in accumulation of pyruvic and lactic acid = acidosis
what is a normal uterine contraction?
5 contractions or less in 10 minutes averaged over a 30 minute window
what is uterine tachysystole?
> 5 contractions in 10 minutes averaged over a 30 minute window
presence or absence of associated FHR decelerations
baseline FHR
110-160
causes of fetal bradycardia (< 100 bpm)
fetal hypoxia (late sign) obstetric anesthesia pitocin maternal hypotension prolapsed or prolonged compression of umbilical cord heart block
causes of fetal tachycardia ( > 160 bpm)
*fetal infection (chorioamnionitis)* most common! fetal hypoxia (early sign) medications arrhythmias prematurity maternal fever
FHR variability
amplitude
decrease may be an indication of fetal distress
causes of decreased variability
prematurity sleep cycle maternal fever fetal tachycardia congenital anomalies maternal hyperthyroidism maternal drugs/substances
are FHR changes during contractions normal?
yes!
acceleration or deceleration
physiological accelerations
an abrupt increase in FHR is a normal and reassuring response
≥ 32 weeks FHR ≥ 15 bpm above baseline for < 2 minutes
< 32 weeks FHR ≥ 10 bpm above baseline for < 2 minutes
causes of physiological accelerations
spontaneous fetal movement
scalp stimulation or vibroacoustic stimulation
vaginal exam
physiological decelerations
occurs in response to uterine contractions:
head compression
umbilical cord compression
late deceleration
caused by uterine placental insufficiency (UPI)
indicates fetal metabolic acidosis and low arterial pH
what type of deceleration occurs during pushing?
prolonged decelerations
≥ 2 mins but < 10 mins
sinusoidal pattern of FHR
smooth, sine wave-like pattern
seen with fetal anemia
category I tracing
baseline 110-160 bpm
moderate variability
no late or variable decelerations
accelerations and early decelerations may be present
tx for recurrent variable deceleration
amnioinfusion to reduce cord compression
normal saline instillation via transcervical IUPC
category II tracing
intermittent variable decelerations recurrent variable decelerations minimal or absent variability recurrent late decelerations prolonged decelerations tachy brady tachysystole variable, late or prolonged during pushing
tx for category II tracing
lateral positioning IVF bolus O2 decreased oxytocin modification of pushing efforts
category III tracing
absent baseline variability
tx for category III tracing
scalp stimulation test
if test shows no acceleration, prepare for delivery
fetal scalp stimulation
used to determine fetal sleep vs acidosis
normal response is acceleration of 15 bpm lasting 15 seconds
does FHR monitoring reduce risk of cerebral palsy?
nope
