CTG
Induction of labour describes a process where labour is started artificially. It happens in around 20% of pregnancies.
Indications
- prolonged pregnancy, e.g. 1-2 weeks after the estimated date of delivery
- prelabour premature rupture of the membranes, where labour does not start
- maternal medical problems
- diabetic mother > 38 weeks
- pre-eclampsia
- obstetric cholestasis
- intrauterine fetal death
Bishop score
The Bishop score is used to help assess whether induction of labour will be required. It has the following components:
|
0 |
1 |
2 |
3 |
| Cervical position |
Posterior |
Intermediate |
Anterior |
- |
| Cervical consistency |
Firm |
Intermediate |
Soft |
- |
| Cervical effacement |
0-30% |
40-50% |
60-70% |
80% |
| Cervical dilation |
<1 cm |
1-2 cm |
3-4 cm |
>5 cm |
| Fetal station |
-3 |
-2 |
-1, 0 |
+1,+2 |
Interpretation
- a score of < 5 indicates that labour is unlikely to start without induction
- a score of ≥ 8 indicates that the cervix is ripe, or 'favourable' - there is a high chance of spontaneous labour, or response to interventions made to induce labour
Management
Possible methods
- membrane sweep
- involves the examining finger passing through the cervix to rotate against the wall of the uterus, to separate the chorionic membrane from the decidua
- can be done by a midwife at the antenatal clinic. Nulliparous women are typically offered this at the 40- and 41-week antenatal visit, whereas parous women are offered it at the 41-week visit
- membrane sweeping is regarded as an adjunct to induction of labour rather than an actual method of induction
- prior to formal induction of labour, women should be offered a vaginal examination for membrane sweeping
- vaginal prostaglandin E2 (PGE2)
- also known as dinoprostone
- oral prostaglandin E1
- also known as misoprostol
- maternal oxytocin infusion
- amniotomy ('breaking of waters')