Induction of labour

INDUCTION OFINDUCTION OF
LABOURLABOUR
Dr Max MongelliDr Max Mongelli
Women & Childrens’ HealthWomen & Childrens’ Health
Nepean HospitalNepean Hospital

DefinitionsDefinitions
IOL: “Iatrogenic stimulation of uterineIOL: “Iatrogenic stimulation of uterine
contractions to accomplish delivery prior to thecontractions to accomplish delivery prior to the
spontaneous onset of labour”spontaneous onset of labour”
Cervical priming: Interventions designed toCervical priming: Interventions designed to
improve the Bishop score without necessarilyimprove the Bishop score without necessarily
inducing labourinducing labour

PrevalencePrevalence
 USA: frequency has increased from 9.5%USA: frequency has increased from 9.5%
to 22.5% over 16 yearsto 22.5% over 16 years
 Due to availability of better cervicalDue to availability of better cervical
ripening agents, more relaxed attitudesripening agents, more relaxed attitudes
towards marginal indications fortowards marginal indications for
inductioninduction

IndicationsIndications
 MaternalMaternal
 FetalFetal

Maternal IndicationsMaternal Indications

Maternal IndicationsMaternal Indications
 Pre-eclampsia/EclampsiaPre-eclampsia/Eclampsia
 Severe hypertensionSevere hypertension
 Gestational diabetesGestational diabetes
Pelvic arthropathyPelvic arthropathy
 Obstetric cholestasisObstetric cholestasis
 Severe cardio-respiratory diseaseSevere cardio-respiratory disease
 ““Social”Social”
 AnticoagulationAnticoagulation

Fetal IndicationsFetal Indications

Fetal IndicationsFetal Indications

Post-term pregnancyPost-term pregnancy
 IUGRIUGR
 Obstetric cholestasisObstetric cholestasis
 PROMPROM
AmnionitisAmnionitis
 Fetal demiseFetal demise

ContraindicationsContraindications

ContraindicationsContraindications
 Classical C/S scarClassical C/S scar
 Transmural myomectomy scarTransmural myomectomy scar
 Placenta or vasa previaPlacenta or vasa previa
 Active genital herpesActive genital herpes
 Large cervical fibroidsLarge cervical fibroids
 MalpresentationMalpresentation
 Cord presentation or prolapseCord presentation or prolapse
 Severe IUGRSevere IUGR
 Abnormal or non-reactive CTGAbnormal or non-reactive CTG

Pre-Induction AssessmentPre-Induction Assessment
 Confirm valid indicationConfirm valid indication
 Exclude contraindicationsExclude contraindications
 Patient information and consentPatient information and consent
 Bishop scoreBishop score

Pre-Induction Assessment:Pre-Induction Assessment:
Bishop ScoreBishop Score

Modified Bishop scoreModified Bishop score

Significance of Bishop scoreSignificance of Bishop score
If Bishop score >5 chance of vaginalIf Bishop score >5 chance of vaginal
delivery after IOL same as afterdelivery after IOL same as after
spontaneous onset of labourspontaneous onset of labour

Predictors of Successful IOLPredictors of Successful IOL

Other Predictors of Successful IOLOther Predictors of Successful IOL
 MultiparityMultiparity
 Tall stature ( > 5 ft 5” or 165 cm)Tall stature ( > 5 ft 5” or 165 cm)
 Normal BMINormal BMI
 Increasing GAIncreasing GA
 EFW < 3500 gEFW < 3500 g

Methods for Induction of LabourMethods for Induction of Labour

MethodsMethods
 Membrane strippingMembrane stripping
 Mechanical methodsMechanical methods
 AmniotomyAmniotomy
 OxytocinOxytocin
 ProstaglandinsProstaglandins

Membrane StrippingMembrane Stripping
 Finger through cervical os, to detach membranesFinger through cervical os, to detach membranes
from LUSfrom LUS
 Usually from 39 weeks onwardsUsually from 39 weeks onwards
 Can be repeated safelyCan be repeated safely
 Reduced risk of going beyond 41 (RR 0.59)Reduced risk of going beyond 41 (RR 0.59)
 Reduced frequency of formal IOL (NNT =8)Reduced frequency of formal IOL (NNT =8)
 May cause slight PV bleeding and crampsMay cause slight PV bleeding and cramps

Mechanical MethodsMechanical Methods
 Required for low Bishop scoresRequired for low Bishop scores
 Ideal when PG’s relatively contraindicatedIdeal when PG’s relatively contraindicated
 Foley’s catheterFoley’s catheter
 ATAD catheterATAD catheter
 LaminariaLaminaria

AmniotomyAmniotomy
 Usually when cx is partially dilatedUsually when cx is partially dilated
 Usually combined with oxytocinUsually combined with oxytocin
 Colour of amniotic fluid should beColour of amniotic fluid should be
notednoted

Risks of AmniotomyRisks of Amniotomy
 Fetal hemorrhage if vasa previaFetal hemorrhage if vasa previa
 Cord prolapse, esp with high headCord prolapse, esp with high head
 InfectionInfection

OxytocinOxytocin
 Almost always after amniotomyAlmost always after amniotomy
 Given i.v. by infusion pump because of short half-lifeGiven i.v. by infusion pump because of short half-life
 May take up to 40 mins to reach steady-stateMay take up to 40 mins to reach steady-state
concentrationsconcentrations
 May be stopped once active phase of labour establishedMay be stopped once active phase of labour established
 Continuous CTG monitoring requiredContinuous CTG monitoring required

Oxytocin regimesOxytocin regimes
 Low-dose: less likely to cause hyperstimulationLow-dose: less likely to cause hyperstimulation
 High dose: short incremental time intervals, noHigh dose: short incremental time intervals, no
more than 40 iu/minmore than 40 iu/min
 Pulsatile regime: boluses at 8-10 min intervals,Pulsatile regime: boluses at 8-10 min intervals,
reduced total overall dose of of oxytocinreduced total overall dose of of oxytocin

Risks of OxytocinRisks of Oxytocin
 Hyperstimulation / tachysystoleHyperstimulation / tachysystole
 Uterine ruptureUterine rupture
 High dose: water intoxicationHigh dose: water intoxication
 Increased risk of PPHIncreased risk of PPH

ProstaglandinsProstaglandins
 Required for low Bishop scoresRequired for low Bishop scores
 PGE2 gel or pessariesPGE2 gel or pessaries
 Slow-release systemsSlow-release systems
 MisoprostolMisoprostol

Prostanoids in Clinical UseProstanoids in Clinical Use
 Dinoprostone (PGE2)Dinoprostone (PGE2)
 Dinoprost (PGF2-alpha)Dinoprost (PGF2-alpha)
 Gemeprost: “cervagem”, analogue of PG E1,Gemeprost: “cervagem”, analogue of PG E1,
for TOPsfor TOPs
 Carboprost (analogue of PGF2-alpha)Carboprost (analogue of PGF2-alpha)
 Misoprostol (stable PGE2 analogue)Misoprostol (stable PGE2 analogue)

Side Effects of ProstaglandinsSide Effects of Prostaglandins

SE’s of ProstaglandinsSE’s of Prostaglandins
 HyperstimulationHyperstimulation
 FeverFever
 Allergic reactionsAllergic reactions
 Exacerbation of asthmaExacerbation of asthma

Other Methods of IOLOther Methods of IOL

Other Methods of IOLOther Methods of IOL
 Nipple stimulationNipple stimulation
 Castor oilCastor oil
 Cervical vibratorsCervical vibrators
 AcupunctureAcupuncture
 SexSex

Prostaglandins in SemenProstaglandins in Semen
 PGE : 67.1 mg/LPGE : 67.1 mg/L
 PGF: 3.2 mg/LPGF: 3.2 mg/L

Patient’s consent for IOLPatient’s consent for IOL
 Indication to be explainedIndication to be explained
 Failure rate and need for C/SFailure rate and need for C/S
 Possible delay in starting IOLPossible delay in starting IOL
 Risks to be explained: cord prolapse, fetalRisks to be explained: cord prolapse, fetal
distress, PPHdistress, PPH
 Alternatives to inductionAlternatives to induction
 Patient info. sheetPatient info. sheet

Induction of labour

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Induction of labour