• Induction of labour involves the use of some methods to initiate uterine contractions before the spontaneous onset of labour• Includes Ripening of cervix. onset of uterine contractions• Purpose Achieve vaginal delivery To avoid operative delivery by cs
RIPENING OF CX• Normal physiological process that precedes ut.contractions & includes highly complex biochemical process• Remodelling of cx occurs towards term * dissociation of collagen bundles * increase in water content of cx * invaded by neutrophils ¯ophages(releases inf cytokines_ IL -1B,IL-8 )
MODIFIED BISHOP SCORE Factor Score 0 1 2 Dilatation <1.5 1.5-3 >3 Effacement(cm) 1.5> intermediat 0.5or less e Station -2 or higher -1 0 or lower Consistency Firm intermediat Soft e Position Posterior Mid Anterior
Prerequisites for IOL Maternal & fetal risk –benefit analysis should be assessed before IOL Informed consent Maternal pelvis assessed Fetal wt. & presentation Confirm lung maturity cx status assessed ---success of induction & outcome
Contraindications to cx ripeningAbsolute CI • Special caution•pl. preavia•Vasa preavia – Previous LSCS• Active genital herpes – Multiple preg.•Invasive ca cx. – Polyhydramnios•Previous ut. Surgery – Mat. Heart ds Classical cs – Severe HTN. Previous metroplasty Myomectomy---cavity opened
ELECTIVE INDUCTION• Induction of labour in the absence of maternal or fetal indication.• Convenience of pt. and obstetrician.• Not encouraged.• Unripe cx. prolonged labour failed induction.
Methods of cx ripening and labour inductionMechanical dilators -Balloon cath -Laminaria -Osmotic dilatorsStripping of membAmniotomyPharmacological Preparation -PGE2 -oxytocin -Misoprostol(PGE1 analogue) -Mifepristone(RU-486) -Relaxin -NO
Mechanical methods• Allows slow and controlled dilatation of cx.• Ideal cx firm, postr.,long and closed severe FGR, oligamnios,• Method (EASI) aseptic precautions foleys catheter inflated with 30ml distilled water 100ml NS extraamniotic space spontaneous passage 12hrs ARM &pitocin•
Stripping of membranesRelease of endogenous PG Risk ascending infection bleeding from pl .preavia accidental rom Advantage - makes spontaneous onset of labour more likely. Reduces the need for formal IOL When? 39 wks
Amniotomy• ARM is commonly used along with oxytocin infusion• Shortens the induction –delivery interval• Ideally ARM done - cx. is favorable• Spontaneous labour - do only in the active phase• Delay ARM - occipitoposterior position.• Oxytocin infusion can be started if ut. Contractions do not ensue in 2-4 hrs.
PROSTAGLANDINS ONLY When cervix is unripe.• Action------- dissolution of collagen bundles increases tissue water content stimulates myometriumPG-E2 (dinoprostone) Preparation and dosages 0.5mg intracervical 2.5mg intravaginalKept refrigeratedBrought to room temp. b/f admn.Contraindications fever allergy to PG abn. Vaginal bleed.
Mode of admn• Studies show that intravaginal route is more superior to IC route (RCOG)• Rcog(2008) does not recommend other routes like; • Oral ,extraamniotic, intracervical PG Intracervical preparation should not be used for Intravaginal application.
Additional dosage?• Pv exam done after 6hrs –no cx response rpt. dose admn.• Maximum recommended cumulative dose is 2 doses*24hrs.• Recommended interval before administering oxytocin( after PG-E2 )is 6- 12 hrs
MISOPROSTOL• More effective than PG-E2 in producing cx ripening• Not approved by FDA for IOL at term.• Advantage inexpensive easy to store stable at room temp.• Risk high incidence of ut. Hyperstimulation thick meconium• Low dose regime--25microgm of PGE1 incidence of tachysystole < by 50%RCOG 2008: PGE1 should only be offered as a method of IOL in IUD or in the context of a clinical trial.
Complications of prostaglandins• Systemic side effects: nausea,vomiting,diarrhoea,fever• Ut. Hyperstimulation » Defined as tachysystole or hypersystole ass. with nonreassuring FHR pattern. » tachysystole—def. as 6>more ut. Contractions in 10 mts. » Hyper systole--- def. as single contraction of at least 2mts duration.
Oxytocin Mechanism of action binds to OTR in the myometrial cell wall and increase intracellular ca conc. increase plasma PG conc. Dosage oxytocin is started as a low dose in normal saline(5U in 500ml NS) and the rate is doubled every 30 mts. 4 drops/mt=2.5mu/mt max dose is 40mu/mt (60 drops/mt) ARM before oxytocin
Guidelines for oxytocin infusion• A written protocol for oxytocin admn. should be available in the labour room.• Unfavorable cx. ---oxytocin should not be used as a primary method of IOL.• All medical personnel who administer oxytocin should be able to identify and manage oxytocin complications.• Once the intensity of contractions increases oxytocin rate should be reduced or stopped.• Partogram• CTG monitoring.
ComplicationsUt. HyperstimulationMgt stop ,left lateral position , O2 inhalation ,iv fluids terbutaline 250 microgm scWater intoxication • Large dose of oxytocin given for prolonged period • Sodium poor iv fluids are used • Hyponatremia-----confusion, convulsions coma death.
Rupture uterus multi ,prev.cs , malpresentations overdistented ut. Cl.presentation nonspecific and variable most imp. Warning sign is FHR variation sudden tearing pain pp may spontaneously lose station p/a- abn .uterine contour shock and referred pain to shoulder---late
RCOG recommendations in Special circumstancesPrevious cs PGE2 & oxytocin is safe in pts .who are candidates for VBAC . PGE1 contraindicated.IUGR - severe FGR with fetal compromise- IOL is not recommendedPPROM- <34 wks-expectant mgt. >34wks---intravaginal PGE2IUD labour induced with oral mifepristone (200mgdaily *2days) foll. by vaginal PGE2 or PGE1IUD with previous cs - dosage of PG should be reduced.
Summary• Stripping of membranes at 39 wks.• ARM only in active phase of labour. delay ARM op position.• Foleys catheter long rigid cx, IUGR• PG ONLY when cx is unripe.• Misoprostol low dose regime - 25 microgm 6th hrly.• Oxytocin start as low dose in NS. do ARM before oxytocin.• Avoid cocktail regimen.