Monitoring in Labour

Objectives

• Discuss fetal heart rate patterns using Continuous Electronic Fetal Monitoring (CEFM) tracings.

• Compare the evidence between EFM and structured intermittent auscultation (SIA) • Discuss relevant physiology in fetal monitoring • Describe systematic approaches in fetal monitoring using Dr C Bravado • Outline guidelines for fetal heart rate monitoring using SIA

CEFM vs. SIA

Perinatal outcomes 50% reduction in neonatal seizures (RR0.50, 95%CI 0.31-0.80) … but

no significant difference

in incidence of: - long-term neurological handicap - or perinatal mortality (RR1.74, 95%CI 0.97-3.11) (RR0.85, 95%CI 0.59-1.23) Obstetric outcomes - 66% increase in C. Section rate - 16% increase in instrumental delivery (RR1.66, 95%CI 1.30-2.13) (RR1.16, 95%CI 1.01-1.32)

Alfiveric Z et al, Cochrane Database Syst Rev 2006

Pathophysiology of FH rate changes

• Changes in FH rate patterns occur in response to changes in O 2 , CO 2 , hydrogen ions and arterial pressure • These changes are mediated via the vagus nerve, chemoreceptors & carotid body baroreceptors • It is difficult to measure fetal oxygenation and pH continuously • FH rate patterns only allow indirect assessment of fetal acid-base balance. Fetal scalp sampling is required to confirm whether the fetus is hypoxic…

Hinshaw K & Ullal A. Anaes Int Care Med (Aug 2007)

A systematic approach to CTG interpretation using EFM

DR. C. BRAVADO

D

etermine

R

isk

C

ontractions (< 5 in 10)

B

aseline

Ra

te (110-150bpm)

V

ariability (>5)

A

ccelerations-reassuring

D

ecelerations

O

verall Assessment & Plan

Few centres in Tanzania have this facility - refer to ALSO manual for further information

“

DR

C BRAVADO”

A systematic approach to CTG interpretation

D

etermine

R

isk

Assess degree of “clinical risk

”

in relation to clinical outcome

• High

Comparable to TRAFFIC LIGHTS

• Low

Risk Factors

Maternal:

• Previous Caesarean section • Pre-eclampsia • Pregnancy >42 weeks • Prolonged ROM >24 hours • Diabetes • Antepartum haemorrhage • Significant medical condition – eg cardiac

Risk Factors

Fetal:

• Intrauterine growth restriction • Oligohydramnios • Preterm labour • Multiple pregnancy • Breech presentation

Risk Factors

Intrapartum • Significant meconium-stained liquor • Abnormal FHR on auscultation  baseline <110 or >160 bpm  any decelerations after a contraction • Maternal pyrexia • Fresh bleeding in labour • Oxytocin augmentation

“

DR

C

BRAVADO”

A systematic approach to CTG interpretation

Assess

c

ontraction pattern

• Rate • Duration of contractions • Coordinate or In-coordinate?

• Baseline Tone

“

DR C

BRA

VADO”

A systematic approach to CTG interpretation

B

aseline

Ra

te

• Normal range 110-160bpm • Baseline Bradycardia <110 • Baseline Tachycardia >160 bpm

BASELINE RATE

BRADYCARDIA<110

• Gestation > 40 weeks • Cord compression • Congenital heart malformations • Drugs eg.benzodiazepines

TACHYCARDIA>160

• Excessive fetal movement • Maternal anxiety • Gestation <32 weeks • Maternal pyrexia • Fetal infection • Chronic hypoxia

“

DR C BRA

V

ADO”

A systematic approach to CTG interpretation

•

V

ariability

The presence of normal fetal heart rate variability is one of the best indicators of intact integration between the central nervous system and the heart of the fetus

Normal ≥5 bpm

VARIABILITY Persistent absence of or reduced variability is potentially ominous Reduced Normal

“

DR C BRAV

A

DO”

A systematic approach to CTG interpretation

A

ccelerations

• Increase of at least 15 bpm above the baseline for at least 15 seconds • Associated with movement or stimulation • Presence is the single best indicator of fetal well-being • An antenatal CTG should always contain accelerations to be considered normal.

ACCELERATIONS

3 examples are highlighted

“

DR C BRAVA

D

O”

A systematic approach to CTG interpretation • Early

D

ecelerations mirror contractions • Fall of <60 beats from baseline associated (almost exclusively) with excellent fetal outcome • True early uniform decelerations are rare and benign and therefore not significant

“

DR C BRAVA

D

O”

A systematic approach to CTG interpretation

Variable D ecelerations

• Most decelerations in labour are variable • Can reflect cord compression • ‘Variable’ in shape, depth and/or onset • Usually benign but …. if late or deep may imply cord prolapse or hypoxia • ‘Need to assess the frequency and duration

VARIABLE DECELERATIONS

COMPLICATED VARIABLES

“ DR C BRAVA

D

O”

A systematic approach to CTG interpretation

Late D ecelerations

• Associated with fetal compromise (hypoxia)

but only in 50-60% of cases

• Ominous if associated with: - fresh particulate meconium ‘high-risk’ clinical situation • Ominous if:  ‘lag-time’ (peak to trough) - deceleration is slow to recover

LATE

DECELERATIONS

• Begin after onset of contraction • Nadir (or trough) after peak of contraction • Return to baseline after end of contraction

Structured Intermittent Auscultation

In Active phase of labour

 MINIMUM OF 60 SECONDS after a contraction  Differentiate maternal pulse  Each 30 minutes in first stage of labour  Each 15 minutes if any risk factor  After each contraction while actively pushing

If fetal heart rate persist above 180 bpm or below 100 bpm plan delivery: • If the cervix is fully dilated and the fetal head is not more than 1/5 above the symphysis pubis (or at station 0 or below) deliver by vacuum • If the cervix is not fully dilated or the fetal head is more than 1/5 above the symphysis pubis (or above station 0) deliver by cesarean section ”Managing obstetric complications, WHO”