Induction of Labour Flashcards
Definition of induction of labour. What is the prevelance of IOL
- The planned initiation of labour prior to its spontaneous onset.
- Around 20% of deliveries in the UK occur following IOL.
- Generally IOL occurs when the risks to the foetus and/or mother of continuing pregnancy outweigh those of delivery.
What are some common indications for IOL
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Prolonged pregnancy lasting longer than 41 weeks. Should give women with uncomplicated pregnancies every opportunity to go into spontaneous labour (labour usually starts naturally before 42+0 weeks)
Should explain that risks associated with continuing pregnancy beyond 41+0 weeks increase over time (increased likelihood of C-section, baby needing NICU admission, meconium aspiration, stillbirth and neonatal death)
In those who choose not to have IOL beyond 42+0 weeks and wish to have foetal monitoring, advise:
* Monitoring only gives a snapshot of the current situation, and cannot predict reliably any changes after monitoring ends
* Adverse effects cannot be predicted reliably even with close monitoring
* Offer opportunity to change decision in the future
Others:
* P-PROM- Do not offer IOL before 34+0 weeks unless there are additional obstetric indications (e.g infection, foetal compromise)- offer expectant management until 37+0 weeks (Should do c-section or IOL if there is any history of GBS).
* PROM at term- Should be offered expectant management for up to 24 hrs or IOL ASAP. Woman’s wishes should be respected if they choose to wait for over 24 hours after prelabour SROM (again should manage immediately with IOL or c-section if history of GBS)
* Previous C-section- women should be advised that IOL can increase the risk of emergency C-section in this circumstance, due to increased risk of uterine rupture. Some methods may not be suitable (e.g dinopostone, misoprostol)
* Maternal request- should discuss risks and benefits with mother
* Breech position- Not generally recommended for breech, but can be considered where ECV has been unsuccessful and c-section is refused/contraindicated
* Intrauterine foetal death (maternal decision)
* Suspected foetal macrosomia: options are expectant management, IOL, c-section:
* With induction of labour the risk of shoulder dystocia reduced compared with expectant management
* With induction of labour the risk of third- or fourth-degree perineal tears is increased compared with expectant management
* There is evidence that the risk of perinatal death, brachial plexus injuries in the baby, or the need for emergency caesarean birth is the same between the 2 options
* Pre-eclampsia and other maternal hypertensive disorders that indicate IOL
* GDM and Obstetric cholestasis
What are some absolute contraindications for IOL
Placenta praevia, severe foetal compromise, breech position (unless ECV unsuccessful an C-section declined). Additionally induction < 34 weeks is likely to be unsuccessful
What is the BISHOP score, how does it equate to initiation of labour
- A numerical value obtained by doing a vaginal examination, based on dilation, effacement (or length), position and consistency of the cervix and station of the foetal head with respect to the ischial spines of the pelvis.
- Score of 8 or more: cervix is ready to dilate- high chance of spontaneous labour, or good response to IOL
- Score of less than or equal to 6= IOL needed to initiate labour
What is a membrane sweep, when can it be indicated
Membrane sweep: Involves the examining gloved finger passing through the cervix to rotate against the wall of the uterus to separate the chorionic membranes from the decidua. If the cervix will not admit a finger, massaging around the cervix in the vaginal fornices may achieve a similar effect.
* This also stimulates the release of prostaglandins
* Might make it more likely that labour will start without the need for additional pharmacological or mechanical methods of induction
* Often offered prior to formal induction to prevent prolongation of pregnancies
* Pain, discomfort and vaginal bleeding is possible
* Offered weekly from 39+0 weeks gestation- can have additional sweeps
* Must exclude placenta praevia
What methods of IOL should be offered to a woman with a score of 6 or less
Offer induction of labour with dinoprostone (PGE2) as vaginal tablet, vaginal gel or controlled-release vaginal delivery system or with low dose (25 microgram) oral misoprostol tablets (preferred in intrauterine death in combination with mifepristone 200mg-> can also offer mechanical)
What methods of IOL should be offered to women with a Bishop score of 6 or less in whom pharmacological methods are unsuitable or refused.
Consider a mechanical method to induce labour (e.g balloon catheter or osmotic cervical dilator)
What methods of IOL should be given to women with a Bishop score more than 6
Offer induction with amniotomy (Artificial rupture of membranes) and IV oxytocin infusion- must do ARM before IV oxytocin (if not= risk of amniotic fluid embolism)
What methods of IOL are contraindicated in VBAC
PGE2 + Misoprostol
How should the risk of cord prolapse be minimised during IOL
Abdominally assess the level and stability of the foetal head and palpate for umbilical cord presentation and avoid dislodging the baby’s head. Carry out continuous CTG
What is dinoprostone, what are some recomended regimens for its use. What are some risks of its use
Prostin- prostaglandin E2- ripens cervix, making It more favourable. Recommended regimens include:
* One cycle of vaginal PGE2 tablets or gel: one dose, followed by a seconddose after 6 hours if labour is not established (up to max of 2 doses)
* One cycle of vaginal PGE2 controlled-release: one dose over 24 hours
* Risk includes vaginal hyperstimulation
What are some mechanical methods of inducing labour. When might they be indicated
- Osmotic cervical dilator- A medical device used to dilate the uterine cervix by swelling as it absorbs fluid from surrounding tissue
- Cervical balloon- balloon is inserted into the cervix and inflated to mechanically inflate the cervix (mainly used in VBAC due to risk of uterine rupture)- this method allows weaker contractions and gradual stretching of the cervix for release of prostaglandins (small risk of infection- left for 12-24 hours)
How is artificial rupture of membranes, when is it contraindicated
- ARM- Instrument called amnihook is passed through the cervix and a small hole is made in the amniotic membrane
- Should not be used first-line for induction and should be avoided if the presenting part is mobile or high
- Risk of umbilical cord prolapse
What is oxytocin, when is it indicated and contraindicated
Syntocinon- infusion rate starts low and increases in defined increments every 30 minutes until 3-5 contractions every 10 minutes
* Should not be used first line for induction- offered if 2 hours after membranes have ruptured, labour has not ensued
* Risk- uterine hyperstimulation and increased risk of uterine rupture especially in VBAC
* Can also be used in augmentation of labour- Vaginal examination should be done 4 hours after starting oxytocin in established labour (further review required if cervical dilatation has increased by <2cm after 4 hours of oxytocin)
Definition and management of failed induction
labour not starting after one cycle of treatment:
* Fully reassess the woman’s condition and the pregnancy in general, and assess fetal wellbeing using antenatal cardiotocography interpretation
* Discuss and agree a plan for further management with the woman, including whether she would like further attempts at induction
Subsequent management options include:
* Offering a rest period if clinically appropriate and then re-assessing the woman
* Expectant management
* Further attempts to induce labour
* Caesarean birth
