INTRAPARTUM FETAL MONITORING

Dr Manal Behery Professor OB&GYNE

2014

Methods available for fetal monitering in labor

Intermittent auscultation

CTG Fetal electrocardiography Scalp stimulation

Vibroacoustic stimulation

Fetal scalp sampling PH determination

Fetal pulse oximetry

Types of Intermittent Monitors

Intermittent Auscultation

The three unique risk factors for fetus during labor

Factor of uterine contraction

Factor of cord accident

Factor of head compression

Factor of uterine contraction

Oxy –Hb 0.19 micromol/100Gm of brain Cerebral O2 saturation 9%• In spite of this slightly worrying picture, Nothing

harmful effect happen if fetus is healthylabor contraction are normalPlacenta has adequate reserve

Factor of head compression

Some degree of compression is inevitable during normal labor But

Excessive compression over long period causing supermoulding as in obstructed labor may cause fetal hypoxia

Factor of cord accident

Only during labor cord prolapse ,presentation and entanglements become apparent either by compression or stretch secondary to uterine contraction

Aim of intrapertum fetal monitering

1- to detect the earliest stages of hypoxia so

therapy can be directed to prevent asphyxia and asphyxial damage( e.g Cerebral palsy)

2-To Improve perinatal morbidity & mortality

What is Cardiotocography(CTG)?

It is a paper record of the continuous FHR blotted simultaneously with a record of uterine activity

Ultrasound (cardio) transducer

Tocotransducer

CTG records

Non stress test without uterine contractionStress test

in correlation to uterine contraction

External monitoring

Internal monitoring

Intrapartum Fetal monitoring CTG

FHR trace(4 components)

Base line FHR

Baseline variability

Accelerations

Decelerations

Baseline FHR

The dominant reading taken ≥10 min

Normal baseline FHR 110-160(pbm)

Controlled by atrial pacemaker

Baseline FHR

Tachycardia FHR>160 bpm

Baseline bradycardia FHR<110bpm

Baseline varibility

The Oscaltatory pattern of FHR when recorded on a graph.

Short term(beat t0 beat) is the fluctuation of HR over short interval

Long term is the fluctuation over long interval(≥2 min) Indicates mature fetal neurologic system

Baseline varibility

Short term variability (scalp electrode)

Long term variabilitydefined as 3-5 cycle/min

Baseline varibility

No variability (0-2 ครั้��ง/นาที)

Mark variability (>25 ครั้��ง/นาที)

Moderate variability (11-25 ครั้��ง/นาที)

No variability (0-2 ครั้��ง/นาที)

Moderate variability (11-25 ครั้��ง/นาที)

Minimal variability (3-4 ครั้��ง/นาที)

Accelaration

Increase in FHR with contraction or with other activities

Increase15pbm lasting 15 sec

Return to base line <2 min

Accelaration

Decelerations Decelerations

Transient slowing of FHR below The baseline level> 15 bpm

and lasting for 15 sec. or more.

Early Decelerations

Uniform

Synchronous with contraction (mirror image) Rarely fall below 110 (pbm) Due to head compression

Should not be disregarded if they appear early in labor or Antenatal.

Early Decelerations

Late Deceleration

Uniform

Start after peak of contractionAssociated with decreased Variability

Reflect a baroreceptor responseIndicate fetal hypoxia

Late Deceleration

Repetitive late decelration

increases risk ofUmbilical artery acidosis

Apgar score < 7 at 5 ms

Cerebral palsy If associated with

decrease or loss ofvariability

Variable Deceleration (the most common type)

Varible in appearance and Timing.May be assoicated with increased variability .

Reflect umbilical cord compression

• Of no clinical significance if non recurrent

.

Variable Deceleration

Tyes of decleration

Prolonged Deceleration deceleration

A deceleration that lasts more than 90 seconds (but less than 10 minutes)

Drop in FHR of 30 bpm or More

Reduction in O2 transfer to placenta.

Associated with poor neonatal outcome

Prolonged Deceleration

What are the features of a normal tracing?

Baseline FHR 110-160 BPM

Baseline Variability > 5 pbm (10-25)

2 Accelerations > 15 BPM > 15 sec / 20 min trace

No decelrations

Normal -Reassuring CTG

Interpertation of CTG

Normal -Reassuring(R)- CTG with all 4 Features

Suspicious (equivocal)- one non reassuring category and reminder are reassuring

Abnormsal -Non reasurring (NR) - 2 or more non-reassuring categories or one or more abnormal categories.

Interpertation of CTG

Consider Intrapartum / antepartum trace.Stage of labourGestationFetal presentation.Any augmentationMedications

Is Normal CTGs always Reassuring?

With normal CTC the chance of fetus to develop hypoxia is 1.5% due to unpredictable acute events

So a normal CTG is always Reassuring

Is NR CTGs always worrisome ?

60% CTG in Labour have 1 abnormal feature

Only 15-20% of NR CTGs are pathological.

High false positive rate with unnecessary operative intervention for fetal distress.

Thus NR CTG is not always worrisome.

?? To reduce CS….

Consider these factors with abnormal CTG

Maturity of the fetus Reduced variability and baseline tachycardia is

conmen in preterm

State of maternal pulseDrugs may cause maternal and fetal tachycaedia

Check blood pressure for hypotension in patients on epidural.

Consider these factors with abnormal CTG

Posture of patient during CTGo Supine position give abnormal tracing o Some cord compression can get released by

change posture and must be tried with variable deceleration

Congenital fetal malformation Color Doppler of fetal heart to exclude congenital

heart block

Correct reversible causes

Change mother position from supine to left lateral position-----increase uterine blood flow

Improve maternal oxygenation—100% O2 by masK

Correct maternal hypotension –IV fluid

Decrease or stop any oxytocin infusion

Remove vaginal prostaglandins

Secondary tests of fetal well-being

Vibro-acoustic stimulation

Used as a substitute for scalp sampling when CTG –is NR

Normal ----------if FHR acceleration > 15 bpm for 15 seconds within 15 seconds after the stimulation with prolonged fetal movements.

Abnormal ----Only 50% have acidotic PH

Fetal blood sampling

If the pH >7.25 --- observe. If the pH 7.2 and 7.25---repeated within 30 minutes.

If the pH <7.2----repeat immediately

If pH still low -- Prompt delivery

Scalp stimulation. Firm digital pressure

Gentile pinch by atramatic Allis forceps

Fetal pulse oximetry.

THANK YOU