Abnormal labour and Induction of labour Flashcards
What percentage of pregnancies are induced?
10-20%
What are obstetric indications for induction of labour?
- Uteroplacental insufficiency
- Prolonged pregnancy - 41-42 weeks
- IUGR
- Oligo/anhydramnios
- Abnormal uterine/umbilical dopplers
- Abnormal CTG
- Severe pre-eclampsia/Eclampsia
- Unexplained antepartum haemorrhage
- Chorioamnionitis
What are medical indications for induction of labour?
- Severe hypertension
- Uncontrolled DM
- Renal disease with deteriorating renal function
- Malignancies
What is induction of labour?
An attempt to artificially instigate labour using medications +/- artificial rupture of the amniotic membranes (performing amniotomy)
How is cervical ripening assessed?
Bishops Scoring
- Dilatation
- Effacement
- Position
- Consistency
- Station
What are absolute contraindications to induction of labour?
- Abnormal lie
- Known pelvic obstruction
- Placenta praevia
- Foetal distress
What is the Bishop’s score used to determine?
Gives a score on cervical change - higher the score the more progressive change there is, indicating that induction of pregnancy is likely to be successful and when an amniotomy is likely to be possible
What are the relative contraindications to induction of labour?
- Previous C-section
- Asthma
Why is previous C-section a relative contraindication to induction of labour?
Uterus has a scar which increases risk of dehiscence/rupture if labour is artificially induced. The risk of rupture is increased with the use of prostaglandins
Why is asthma a relative contraindication of induction of labour?
Prostaglandins can cause respiratory smooth muscle contraction
What medications are used in the induction of labour?
- Prostaglandin analogues - Dinoprostone, Misoprostol
- Oxytocin
What type of prostaglandin analogue is Dinoprostone?
Prostaglandin E2 analogue
What type of prostaglandin analogue is Misoprostol?
Prostaglandin E1 analgogue
What is the mechanism of action of prostaglandin analogues in induction of pregnancy?
Encourage cervical dilatation and effacement - ripening
What are adverse effects of prostaglandin analogues used for induction of labour?
- Severe/hypertonic contractions
- Nausea and vomiting
- Bowel upset
- Pyrexia
- Hypotension
What needs to be regularly monitored when using prostaglandin analogues?
Foetal heart - CTG
What is the mechanism of action of oxytocin in the induction of labour?
Initiates uterine contraction by attaching to uterine oxytocin receptors, increasing the frequency and force of contractions
What type of drug is oxytocin?
Cyclic nonapeptide
How are prostaglandin anaolgues administered?
PV
How is oxytocin administed for induction of labour?
IV
When is amniotomy performed in induction of labour?
Once cervix has effaced an dilated - Bishops > 7
When is oxytocin given in induction of labour?
Often used following prostaglandin treatment, once amniotomy has been performed
What monitoring needs to be done whilst giving a women an oxytocin infusion for induction of labour?
CTG monitoring
What are risks of oxytocin use in induction of labour?
- Uterine hypertonicity
- Hypotension
- Hyponatraemia
What does amniotomy cause release of?
Local prostaglandins - causes cervical ripening and myometrial contractions
Why is oxytocin often given at the time of amniotomy in induction of labour?
Decreases induction-delivery time, thereby decreasing both the foetal and maternal risk of sepsis
What are risks of trying to induce labour?
- Prematurity
- Drug side effects
- C-section due to failed induction
- Atonic PPH
- Intrauterine infection with prolonged induction
Why should you monitor U+Es in someone being given oxytocin?
Has similar effects to ADH - look for dilutional hyponatraemia
How would you induce for intrauterine death at term?
25 mcg misoprostol every 2-4 hrs
When is labour augmentation required?
When contractions reduce frequency or strength in active labour even after spontaneous onset of labour
What needs to be determined before using medications to augment labour?
Woman needs to be assessed for signs of causes of lack of progress of labour e.g. obstruction due to malposition, which contractions could result in harm to foetus
What is used to augment labour?
IV oxytocin infusion
What are reasons for slow progress at stage 1 of labour?
- Power - Inefficient uterine contraction
- Passenger - Malposition/malpresentation, Large Baby
- Passages - Inadequate pelvis