Intrapartum

[OBSTETRICS] INTRAPARTUM ASSESSMENT

INTRAPARTUM ASSESSMENT



 Nowadays, almost all women undergo electronic fetal
heart rate monitoring during labor. It used to be that this
was introduced only to those who were high risk.


INTERNAL ELECTRONIC FETAL HEART RATE MONITORING
 Fetal Heart Rate is measured by attaching a bipolar spiral
electrode that penetrates the fetal scalp

 This means that the bag of water is to be ruptured
 A small incision is made to attach the spiral
electrode to the scalp (Picture Above) FETAL ECG (SCALP ELECTRODE):
PREMATURE ATRIAL CONTRACTION
 P wave, QRS complex and T wave is amplified  Sometimes, if the time interval from one R to the next R
 R wave voltage is shorter, it may be due to heart rate acceleration 
 Portion of the ECG most reliably detected May be interpreted as Premature Atrial Contraction
(PAC)
 t2  Shorter = Premature Atrial Contraction


EXTERNAL (INDIRECT) ELECTRONIC FETAL HEART RATE
MONITORING
 Fetal Heart Rate is detected through the maternal
abdominal wall using UTZ Doppler principle

 This is a non-invasive technique of electronic fetal
heart rate monitoring
 Most commonly used in most hospitals
(Picture Above) INTERNAL ELECTRONIC FETAL HEART RATE - You do not have to rupture the bag of water
MONITORING - You do not have to puncture the scalp and attach
 Electrode is attached to the fetal scalp  Attached to the the fetal electrode
cardiac monitor
 Consist of a transducer that emits UTZ and a sensor to detect
 Cardiac monitor will register the FHR pattern
a shift in frequency of the reflected sound
 F: Fetal heart wave secondary to fetal heart rate
 Coupling gel must be applied because air conducts UTZ
 M: Maternal heart rate  Weaker one
poorly
 Although the scalp electrode is attached to the fetus,
because of the loud sound produced by the maternal
heart rate, this can also be reflected. But since
electrode is attached to the fetal scalp, then,
understandably, this fetal heart pattern should be
more prominent
 However, if the fetus is dead and the scalp lead is
attached to the fetus, then the maternal heart sounds
will be louder and more prominent, and you will not
be able to appreciate the fetal heart rate at all.

 Time (t) in Milliseconds  Time interval between two R-
waves
 Premature Atrial Contraction  Heart rate acceleration
when the interval (t2) is shorter than the preceding one
 Beat to Beat Variability  Phenomenon of continuous R-to- (Picture Above) EXTERNAL (INDIRECT) ELECTRONIC FETAL
R wave fetal heart rate computation HEART RATE MONITORING

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, [OBSTETRICS] INTRAPARTUM ASSESSMENT


 Doppler is placed on the abdomen to where the fetal  30 beats per minute/per vertical cm (30-240 beats/min)
heart tones are most audible.  3 cm/min chart recorder paper speed

 We use the faster 3cm/min paper speed rather than
the slower 1cm/min paper speed because the slower
 AUTOCORRELATION
1cm/min paper speed will not reflect the variations in
 Reflected UTZ signals from moving fetal heart valves are
the fetal heart rate pattern.
analyzed through a microprocessor that compares
incoming signals with the most recent previous signal
 Based on the premise that the FHR has regularity whereas BASELINE FETAL HEART ACTIVITY
“noise” is random without regularity  Refers to the modal characteristics that prevail apart from
periodic accelerations or decelerations associated with
 Before the cardiac tracing appears on the togograph
uterine contractions
paper, electronic editing is done by the monitor
 Beat-to-Beat variability, Fetal Arrhythmia
 Noise will be eliminated and what will be seen in
the cardiotocogram will be the fetal tracing  Beat-to-Beat Variability  Also same as baseline fetal
heart activity
DISADVANTAGES  Sinusoidal or Saltatory Fetal Heart Rates
INTERNAL ELECTRONIC EXTERNAL ELECTRONIC  Normal Baseline FHR  110-160 beats/min
FETAL HEART RATE FETAL HEART RATE
MONITORING MONITORING BRADYCARDIA
 Necessitates membrane  Does not provide the  FHR <110 beats per minute
rupture and uterine precision of FHR  Mild = 100 – 119 (No fetal compromise)
invasion measurement or the  Moderate = 80 – 100
quantification of uterine
 Severe = <80 lasting for 3min
pressure afforded by
internal monitoring
POSSIBLE CAUSES OF FETAL BRADYCARDIA:
 Congenital Heart block
 Internal Electronic FHR Monitoring
 Fetal Compromise
 More accurate
 Maternal Hypothermia
 External Electronic FHR Monitoring
 Severe Pyelonephritis
 Non-invasive procedure  Less prone to
complications
 Maternal Hypothermia
 Usually during general anesthesia
SCALING FACTORS
TACHYCARDIA
 FHR > 160 beats per minute
 Mild = 161-180
 Severe = >180

POSSIBLE CAUSES OF FETAL TACHYCARDIA:
 Maternal Fever
 Maternal Infection
 Fetal Compromise
 Cardiac Arrhythmias
 Administration of Parasympathetic Drugs (Atropine)
 Sympathomimetic Drugs (Terbutaline)

(Picture Above) Fetal heart rate obtained by scalp  Maternal Fever
electrode (upper panel) and recorded at 1 cm/min  Most commonly due to premature rupture of
compared with that at 3 cm/min chart recorder paper membrane leading to chorioamnionitis
speed. Concurrent uterine contractions are shown (lower
panel).  Key features to distinguish fetal compromise in association
w/ tachycardia  Concomitant Heart Rate Decelerations

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