Stimulation of Labour and Myometrial Relaxation

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

Oxytocic’s are indicated for:

  • Augmentation of labour
  • Induction of labour
  • Active  management  of  third  stage of labour.
  • Uterine stimulation after delivery for management of PPH due to uterine atony

Induction of Labour 

  • Indications/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 section5 
    • 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  chose  to  delay  induction  >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 

A:  misoprostol  (PO)  25µg  2  hourly  for  24hours  or  Misoprostol  (PV)  25µg  6hourly  for 24hours  can  be  considered  a  safe  and      effective  agent  for  labour  induction  with  intact  membranes and on an inpatient basis. 

OR 

S: dinoprostone (PV) 3mg 6hourly a total of 2doses 

Note:  

  • Misoprostol should not be used in the setting of vaginal birth after Caesarean section due to the increased risk of uterine rupture.
  • Oxytocin should be started no earlier than 4hours after the last dose of misoprostol.

Options for induction with a favourable cervix 

  • Amniotomy should be reserved for women with a favorable cervix. Care should be given in the 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 (GBS) 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 the various concentrations, oxytocin infusion rates should always be recorded in mU/min rather than mL/hr.
  • Oxytocin  induction  maybe  considered  in  the  hospital  setting  of  vaginal  birth  after Caesarean section.
  • For induction of labour use: Oxytocin IV, the dose will depend on parity.

Primigravida 

A: oxytocin (IV) 5IU in 500mls of 0.9% sodium chloride the initial dose should be  8-10drops/Minute, the titration may be gradually increased at intervals not shorter than  20  minutes  and  increments  of  not  more  than  5drops/minute,  until  a contraction pattern similar to that of normal labour is established. The recommended maximum rate is 40d/m.

Multiparous 

A: oxytocin (IV) start with low dose e.g., 2.5IU in 500mls of fluid titrate as above.  Regulate the dose according to response. 

Note 

  • Induction of labour with uterotonic drugs requires vigilant monitoring
  • Induction of labour should only be attempted at hospitals with capacity to perform Caesarea section

Augmentation of Labour 

If labour progress is not optimum labour augmentation is necessary. Can be achieved by: 

A: oxytocin as above 

OR 

Artificial  rupture  of  membranes  (ARM)  and  oxytocin.  If  membranes  are  already  ruptured  and  no  labour progress the steps above should be followed; rule out obstruction before augmenting labour  with oxytocin. 

Myometrial stimulation after delivery 

A:  oxytocin  (IM)  10IU  after  delivery  of  the  infant;  when  no  response  give  oxytocin  (IV infusion) 20 units in 500mls of NS running at 10–20 drops per minute. 

OR 

C: ergometrine (IM) 0.25–0.5mg after delivery of the infant, in the absence of myometrium contraction and to prevent postpartum hemorrhage. 

OR 

A: misoprostol (PO/PV) 800–1000µg 

Note: Use Ergometrine cautiously in cardiac and hypertensive disease patients 

Myometrium relaxation (Tocolysis) 

It is done to relax the uterus in order to: 

  • Relieve  fetal  distress  immediately prior to Caesarian section
  • Stop uterine contractions in premature labour
  • Prevent uterine rupture
  • Perform external cephalic version

Pharmacological Treatment 

B: nifedipine (PO) 20 mg stat, followed by 10–20mg 6–8hourly 

OR 

B: salbutamol (PO) 4mg stat, when required (maximum daily dose 32mg) 

Note:  

  • β -stimulants should never be used if the patient had an antepartum hemorrhage
  • β  -stimulants  are  contra-indicated  for  cardiac  disease  and  severe  anemia  in pregnancy