Stimulation of labour/labor and myometrial relaxation

Myometrium stimulants should be used with great care before delivery especially in porous women. Use in obstructed labour/labor should be avoided.

Oxytocics are indicated for:

• Augmentation of labour

• Induction of labour

• Active management of third stage of labour

• Uterine stimulation after delivery for management of postpartum haemorrhage due to uterine atony

Induction of labour indications and contraindications

• The indication for induction must be documented, and discussion should include reason for induction, method of induction, and risks, including failure to achieve labour and possible increased risk of Caesarean section

• If induction of labour is unsuccessful, the indication and method of induction should be re-evaluated

Pre-induction assessment

• Health care providers should assess the cervix (using the Bishop score) to determine the likelihood of success and to select the appropriate method of induction

• The Bishop score should be documented

• Care providers need to consider that induction of women with an unfavorable cervix is associated with a higher failure rate and increased rate of operative deliveries

Post-dates induction

• Women should be offered induction of labour between 41+0 and 42+0 weeks as this intervention may reduce perinatal mortality and meconium aspiration syndrome without increasing the Caesarean section rate

• Women who choose to delay induction beyond 41+0 weeks should undergo twice-weekly assessment for fetal wellbeing

Options for cervical ripening / induction: unfavorable cervix

• Intracervical Foley catheters are acceptable agents that are safe both in the setting of a vaginal birth after Caesarean section and in the outpatient setting

• Double lumen catheters may be considered a second-line alternative

Pharmacological treatment

• Misoprostol (PO) 25 micrograms 2 hourly for 24 hours OR misoprostol (PV) 25 micrograms 6 hourly for 24 hours can be considered a safe and effective agent for labour induction with intact membranes and on an inpatient basis

  
  

  OR

• Dinoprostone (PV) 3 mg 6 hourly, total of 2 doses

Important notes

• Misoprostol should not be used in the setting of vaginal birth after Caesarean section due to increased risk of uterine rupture

• Oxytocin should be started no earlier than 4 hours after the last dose of misoprostol

Options for induction with a favourable cervix

• Amniotomy should be reserved for women with a favourable cervix. Care should be given in case of unengaged presentation because there is a risk of cord prolapse

• After amniotomy, oxytocin should be commenced early in order to establish labour

• In the setting of ruptured membranes at term, oxytocin should be considered before expectant management

• Women positive for group B streptococcus should be started on oxytocin as early as possible after ruptured membranes in order to establish labour within 24 hours

• Both high- and low-dose oxytocin may be considered within a hospital protocol

• Because of various concentrations, oxytocin infusion rates should always be recorded in mU/min rather than mL/hr

• Oxytocin induction may be considered in hospital setting of vaginal birth after Caesarean section

Oxytocin for induction of labour

Primigravida:

• Oxytocin (IV) 5 IU in 500 mL of 0.9% sodium chloride

• Initial dose 8–10 drops per minute

• Titrate gradually at intervals not shorter than 20 minutes

• Increase by not more than 5 drops per minute until a contraction pattern similar to normal labour is established

• Maximum rate 40 drops per minute

Multiparous:

• Oxytocin (IV) start with low dose e.g. 2.5 IU in 500 mL of fluid

• Titrate as above

• Regulate dose according to response

Notes

• Induction of labour with uterotonic drugs requires vigilant monitoring

• Induction of labour should only be attempted at hospitals with capacity to perform Caesarean section

Augmentation of labour

If labour progress is not optimum, augmentation is necessary. It can be achieved by:

• Oxytocin as above

  
  

  OR

• Artificial rupture of membranes and oxytocin

If membranes are already ruptured and no labour progress, the above steps should be followed; rule out obstruction before augmenting labour with oxytocin

Myometrial stimulation after delivery

• Oxytocin (IM) 10 IU after delivery of the infant; when no response give oxytocin (IV infusion) 20 units in 500 mL of normal saline running at 10–20 drops per minute

  
  

  OR

• Ergometrine (IM) 0.25–0.5 mg after delivery of the infant in the absence of adequate myometrial contraction and to prevent postpartum haemorrhage

  
  

  OR

• Misoprostol (PO/PV) 800–1000 micrograms

Important note

• Ergometrine should be used cautiously in cardiac and hypertensive disease patients

Myometrial relaxation (tocolysis)

It is done to relax the uterus in order to:

• Relieve fetal distress immediately prior to Caesarean section

• Stop uterine contractions in premature labour

• Prevent uterine rupture

• Perform external cephalic version

Pharmacological treatment

• Nifedipine (PO) 20 mg stat, followed by 10–20 mg 6–8 hourly

  
  

  OR

• Salbutamol (PO) 4 mg stat, when required (maximum daily dose 32 mg)

Notes

• Beta stimulants should never be used if the patient had an antepartum haemorrhage

• Beta stimulants are contraindicated in cardiac disease and severe anaemia in pregnancy