Induction of labour

Question 1

What is induction of labour?

Answer 1

The process of starting labour artificially

Question 2

What proportion of pregnancies require an induction?

Answer 2

1 in 5

Question 3

When is induction of labour performed?

Answer 3

When it is thought the baby will be safer delivered than remaining in utero or for reasons concerning the mothers health

Prolonged gestation (40+0 - 40+14 weeks)

Premature rupture of membranes (>37weeks)

Maternal health problems - maternal hypertension, pre-eclampsia, diabetes and obstetric cholestasis

Foetal growth restriction

Intrauterine foetal death - if mother physically well with intact membranes

Question 4

What is the aim of IOL in foetal growth restriction?

Answer 4

Aim to deliver baby prior to foetal compromise

Question 5

List the absolute contraindications to induction of labour

Answer 5

Cephalopelvic disproportion

Major placenta praevia

Vasa praevia

Cord prolapse

Transverse lie

Active primary genital herpes

Previous classical caesarean section - can be performed if consultant thinks is safe however increased risk of emergency c-section and uterine rupture

Question 6

List the methods of induction

Answer 6

Vaginal prostaglandins
Amniotomy
Membrane sweep

Question 7

How do vaginal prostaglandins work?

Answer 7

Prepare the cervix for labour by ripening it and have a role in the contraction of the smooth muscle of the uterus

Question 8

What preparations do vaginal prostaglandins come in?

Answer 8

Tablet
Gel
Controlled release pessary

Question 9

Describe the tablet/gel prostaglandin regimen

Answer 9

1 cycle = 1st dose, plus a 2nd dose if labour has not started 6 hrs later

Question 10

Describe the pessary regimen of prostaglandins

Answer 10

1 cycle = 1 dose over 24 hours

Question 11

What is amniotomy

Answer 11

Where the membranes are ruptured articicially using an amnihook

Releases prostaglandins in an attempt to expedite labour

Only performed when cervix is deemed as ripe

Often infusion of oxytocin (syntocinon) will be given alongside acting to increase the strength and frequency of contractions - aim is to start low and titrate up until 4 contractions every 10 mins

Question 12

What is a membrane sweep?

Answer 12

Insert a gloved finger through the cervix and rotate it against foetal membranes, aiming to separate the chorionic membrane from the decidua - helps to release natural prostaglandins in an attempt to kickstart labour

Question 13

When is membrane sweep offered?

Answer 13

40-41 weeks gestation to nulliparous women

41 weeks to multiparous women

Question 14

What is the Bishop score?

Answer 14

Assessment of cervical ripeness - based on measurements taken during vaginal examination

Checked before induction and during induction to assess progress

Question 15

What does a bishop score of >7 indicate?

Answer 15

Cervix is ripe or favourable - high chance of a response to interventions made to induce labour

Question 16

What does a bishop score of <4 indicate?

Answer 16

Labour is unlikely to progress naturally and prostaglandin gel/tablet/pessary will be required

Question 17

How is station of the foetus measured?

Answer 17

in relation to ischial spine

Question 18

Describe how cardiotocography is used to monitor in induction of labour

Answer 18

Prior to induction a reassuring foetal HR must be confirmed
After initiation of IOL, when contractions begin assess foetal heart rate using continuous CTG until normal rate is confirmed
Subsequently assess using intermittent auscultation
If an oxytocin infusion is started, monitor using continuous CTG throughout labour

Question 19

List the complications of induction of labour

Answer 19

Failure of induction
Uterine hyperstimulation  
Cord prolapse
Infection 
Pain 
Increased rate of further intervention 
Uterine rupture

Question 20

What is offered for failure of induction?

Answer 20

Further cycle of prostaglandins or c-section

Question 21

Describe uterine hyperstimulation

Answer 21

Contractions last too long and are too frequent

Question 22

What can uterine hyperstimulation cause?

Answer 22

Foetal distress

Question 23

How is uterine hyperstimulation managed?

Answer 23

Terbutaline - tocolytic agent (anti-contraction)