Induction of Labour Flashcards
What is induction of labour?
The process of starting labour artifically
What proportion of pregnancies will require induction?
Approx 1 in 5
In general, why might IoL be performed?
- If it is thought that the baby will be safer delivered than remaining in utero
- If there are concerns regarding the mother’s health
What are the indications for induction of labour?
- Prolonged gestation
- Premature rupture of membranes
- Maternal health problems
- Fetal growth restriction
- Intrauterine fetal death
When should women with uncomplicated pregnancies be offered induction?
Between 40+0 and 40+14 week’s gestation
What is the aim of inducing labour in prolonged pregnancy?
Avoid the risks of fetal compromise and stillbirth associated with prolonged gestation
What should be done if the patient declines induction of labour for prolonged gestation?
The frequency of monitoring from 42 weeks onwards should be increased
What should be done for premature rupture of membranes over 37 weeks?
Either IoL or expectant management for a maximum of 24 hours
What % of women will spontaneously go into labour within the first 24 hours of premature rupture of membranes?
84%
Why should women not go for more than 24 hours with premature rupture of membranes?
Increases the risk of chorioamnioitis
What should be done in preterm premature rupture of membranes if <34 weeks gestation?
Delay IOL unless obstetric factors indicate otherwise, e.g. fetal distress
What should be done in preterm premature rupture of membranes if >34 weeks gestation?
The timing of IOL depends on risk vs beenfits of delaying pregnancy further, e.g. increased risk of infection
What maternal health problems are common indications for IOL?
- Hypertension
- Pre-eclampsia
- Diabetes
- Obstetric cholestasis
What is the second most common indication for induction of labour?
Fetal growth restriction
What is the aim of IOL for fetal growth restriction?
To deliver the baby before there is fetal compromise
When should IOL be offered for intrauterine fetal death?
If the mother is physically well with intact membranes
What are the absolute contraindications for IOL?
- Cephalopelvic disproportion
- Major placenta praevia
- Vasa praevia
- Cord prolapse
- Transverse lie
- Active primary genital herpes
- Previous classical C-section (midline incision)
What are the relative contraindications for IOL?
- Breech presentation
- Triplet or higher order pregnancy
- Two or more previous low transverse C-sections
Can IOL be offered to women who have had a previous C-section?
Yes, after she has been seen and assessed by a consultant
What should a woman having IOL after a previous C-section be made aware of?
She is at increased risk of emergency C-section and uterine rupture
What are the main methods of IOL?
- Vaginal prostaglandins
- Amniotomy
- Membrane sweep
What methods of IOL have a lack of evidence
- Homeopathy
- Acupuncture
- Sex (with the partner not a HCP)
What is the mainstay of induction of labour and the preferred primary method by NICE?
Vaginal prostaglandins
How do vaginal prostaglandins work in IOL?
They prepare the cervix for labour by ripening, and has a role in contraction of smooth muscle of uterus
What forms do vaginal prostaglandins come in?
- Tablet
- Gel
- Controlled-release pessary
What constitutes 1 cycle of the tablet/gel routine of vaginal prostaglandins for IOL?
1 cycle = 1st dose + 2nd dose if labour not started within 6 hours
What constitutes 1 cycle of the pessary regime of vaginal prostaglandins for IOL?
1 cycle = 1 dose over 24 hours
What is the recommended maximum number of cycles when using vaginal prostaglandins for IOL?
1 cycle in 24 hours
How long can IOL with vaginal prostaglandins take?
Days
What is an amniotomy?
Where membranes are ruptured artificially using an instrument called an amnihook
How does amniotomy work
It releases prostaglandins in an attempt to expedite labour
When can amniotomy be peformed?
Only if the cervix is deemed as ripe
What is often given alongside an amniotomy?
An infusion of artificial oxytocin (Syntocinon)
What is the purpose of giving Syntocinon alongside amniotomy?
To increase the strength and frequency of contractions
How is the dose of Syntocinon given alongside amniotomy determined?
Start low and titrate upwards, until there are 4 contractions every 10 minutes
What are the NICE guidelines regarding the use of amniotomy +/- oxytocin?
It should not be used as the primary method of IOL, unless the use of prostaglandins is contraindicated.
Give an example of when the use of prostaglandins might be contraindicated
High risk of uterine hyperstimulation
When is the membrane sweep indicated?
Between 40 and 41 weeks gestation in nulliparous women, and 41 weeks in multiparous women
What is the membrane sweep classified as?
An adjunct to IOL
What does performing a membrane sweep achieve?
It increases the likelihood of spontaneous delivery, reducing the need for formal induction
How is the membrane sweep performed?
By inserting a gloved finger through the cervix and rotating it against the fetal membranes
What is the aim of the membrane sweep?
To separate the chorionic membrane from the decidua
What does separating the chorionic membrane from the decidua achieve?
Helps to release natural prostaglandins in an attempt to kick-start labour
What monitoring is done in induction of labour?
- Bishop’s score
- Cardiotocography
What is the Bishop’s score an assessment of?
Cervical ripeness
What is the assessment of cervical ripeness in the Bishop’s scored based on?
Measurements taken during vaginal examination
When is the Bishop’s scored checked?
Prior to induction, and during induction to assess progress (6 hours post tablet/gel, 24 hours post pessary)
How is the Bishops score interpreted?
- A score of 7 or more suggests the cervix is ripe or ‘favourable’
- A score of under 4 suggests that labour is unlikely to progress naturally, and prostaglandin tablet/gel/pessary will be required
What does the cervix being ‘favourable’ mean?
There is a high chance of a response to interventions made to induce labour
What might happen if there is a failure of the cervix to ripen despite the use of prostaglandins?
May need C-section
When should a CTG be used in induction?
- Prior to induction of labour
- After induction of labour, when contractions begin
- If oxytocin infusion is started
Why should a CTG be done before the induction of labour?
A reassuring fetal heart rate must be confirmed by CTG
What CTG monitoring should be done after the induction of labour, when contractions begin?
Fetal heart rate should be assessed using continuous CTG until a normal rate is confirmed
How should the fetal heart rate be assessed after induction of labour when the CTG has confirmed a normal heart rate?
Intermittent auscultation
What CTG monitoring should be done if oxytocin infusion is started?
Continuous CTG throughout labour
What are the complications of induction of labour?
- Failure of induction
- Uterine hyperstimulation
- Cord prolapse
- Infection
- Pain
- Increased rate of further intervention
- Uterine rupture
In what % of cases does failure of induction occur?
15%
What should be done if failure of induction occurs?
Should offer a further cycle of prostaglandins, or C-section
In what % of cases of IOL does uterine hyperstimulation occur?
1-5%
What is uterine hyperstimulation?
When contractions last too long or are too frequent
What can uterine hyperstimulation lead to?
Fetal distress
How can uterine hyperstimulation caused by IOL be managed?
Tocolytic agents, such as terbutaline
When can cord prolapse occur in IOL?
At the time of amniotomy, particularly when the presentation of the fetal head is high
How is the risk of infection during IOL reduced?
By using pessary (vs tablet/gel)
Why is the risk of infection during IOL reduced when using the pessary?
Fewer vaginal examinations are required to check progress
Is IOL more or less painful than spontaneous labour?
More
What is often required as pain relief in IOL?
Epidural
What % of cases of IOL require an emergency C-section
22%
What % of cases of IOL require instrumental delivery?
15%
