Induction of labour

Question 1

What is the definition of induction of labour?

Answer 1

-An intervention to initiate the onset of labour in situations where the benefits of ending the pregnancy outweigh those of continuing it

Question 2

What are some indications for IOL?

Answer 2

NB not exhaustive
MATERNAL
-Diabetes
-Maternal cardiac disease
-HTN / pre-eclampsia
-Poor obstetric history
-Maternal choice
FOETAL
-IUGR
-Reduced foetal movements
-Suspected foetal macrosomia
-Intrauterine foetal death
OBSTETRIC
-Post-dates (increased risk of stillbirth)
-Pre-labour rupture of membranes (PPROM)
-Antepartum haemorrhage

Question 3

What are the contra-indications for IOL?

Answer 3

ABSOLUTE
-Acute foetal compromise
-Unstable lie (foetus moving a lot, needs to be cephalic)
-Placenta praevia
-Pelvic obstruction
RELATIVE
-Previous C-section (risk of rupturing uterine scarring)
-High parity
-Prematurity
(-Breech presentation)

Question 4

What order does the sequence of induction follow?

Answer 4

1. Membrane sweep
2. or 3. Mechanical cervical dilatation
3. or 3. Vaginal prostaglandins
4. Artificial Rupture of Membranes (ARM)
5. Oxytocin infusion protocol
6. Birth
   NB not all women will have every step

Question 5

What does a membrane sweep / stretch and sweep involve?

Answer 5

-Can initiate induction or done pre-emptively in order to prevent needing an induction
-Offered to every woman at 38-41 weeks
-Vaginal examination involving entering the cervix and using the examining finger to separate the chorionic membrane from the decidua
-Works by initiating the release of local prostaglandins which may trigger labour, encouraging effacement and dilation

Question 6

How is the cervix optimised for induction of labour?

Answer 6

MECHANICAL
-Using balloon or rod methods
PHARMACOLOGICAL
-Vaginal prostaglandins
-Inserted vaginally into posterior fornix via pessary
-Soften and shorten the cervix and cause uterine tightening
-May require several doses

Question 7

How are membranes artificially ruptured (ARM)?

Answer 7

-Using amniohook inserted through the cervix to make a hole in the membrane
-Stimulates changes to cervix partly through 1) hormone reactions increasing oxytocin and 2) increasing pressure of the foetal head on the cervix

Question 8

What occurs during augmentation?

Answer 8

-Use oxytocin (aka syntocinon when used exogenously)
-Given via slow IV infusion
-Dose titrated against contractions until they are regular / 3-4 every 10 mins
-Tocolytic (terbutaline) used in case of uterine hyper stimulation

Question 9

What are some complications of IOL?

Answer 9

-Hyperstimulation ie too many contractions (prostaglandins and syntocinon)
-Foetal distress
-Precipitate delivery
-Operative vaginal delivery
-Uterine hypertonia –> rupture
-Amniotic fluid embolus
-Cord prolapse if presenting part is not engaged

Question 10

What is the guidance for PROM?

Answer 10

PROM = pre-labour rupture of membranes
-After rupture of membranes, women most likely go into labour within 24h-48h
–Labour is highly unlikely to start spontaneously after 24h
–Offer all term women IOL at 24h due to risk of infection

Question 11

What is the Modified Bishop’s Score?

Answer 11

-Defines the method of induction
-If score 5 or less then labour is unlikely to commence without induction
-Considers:
–Dilation of cervix
–Length of cervix
–Level of descent of presenting part
–Cervical consistency
–Cervical position

Question 12

How is a cord prolapse managed?

Answer 12

-Tocolytics reduce cord compression
-Elevate to avoid compression
-Left lateral positioning
-Do not push cord back into the uterus
-Immediate C-section