INDUCTION ANDAUGMENTATION OF LABOUR PRESENTED BY : Prof. M.C.Bansal MBBS., MS., FICOG., MICOG. Founder Principal & Controller, Jhalawar Medical College & Hospital Jjalawar. MGMC & Hospital , sitapura ., Jaipur
INTRODUCTION•The culmination of normal pregnancy involves three stages: prelabour,cervical ripening and labour.•Endogenous prostaglandins play a part in all these processes.•Interventions to artificially ripen the cervix, induce uterine contractions and augment labour once it is in progress also lack distinct boundaries.•Labour induction and augmentation may be a source of conflict and distress.•For most health workers they are seen as routine, technical procedures.
INTRODUCTION•For many women, they have emotive connotations, evoking a sense of personalinadequacy and eroded self-esteem.•It is important for health workers to approach the question of labour inductionwith sensitivity, and to involve women in the decision-making process.•Labour induction is one of the most frequent medical procedures in pregnantwomen.•It is a major intervention in the normal course of pregnancy, with the potential toset in motion a cascade of interventions, particularly Caesarean section.•However, with modern methods of labour induction, this risk appears to havediminished.
Definition:Induction of Labor (IOL) is defined as artificialstimulation of uterine contractions before theonset of labor.Augmentation refers to stimulation ofspontaneous contractions that are consideredinadequate because of failed cervical dilationand fetal descent.
The goal of IOL is to eliminate the potentialrisks to the fetus with prolonged intrauterineexistence while minimizing the likelihood ofoperative deliveryThe overall incidence of IOL has increasedglobally. In a survey by the National Center forHealth Statistics the rate of labor inductionwas noted to have increased from 90 per1,000 live births in 1989 to 184 per 1,000 livebirths in 1997 (1).
Indications For induction:•Hypertensive disorders of pregnancy ( pre-eclampsia, eclampsia,chronic hypertension)•Diabetes, renal disease, chronic pulmonary disease•Premature rupture of membranes•Chorioamnionitis•Fetal growth restriction•Rh isoimmunization•Postdated pregnancy•Fetal demise•Abruptio placentae•Fetal malformations incompatible with life•Logistic factors: Risk of rapid labor, distance from hospital, psychosocialindications
Contraindications to the induction of labor:•Major degree of Placenta praevia•Vasa praevia•Previous classical uterine incision or incision becauseof metroplasty or extensive myomectomy when thecavity is opened•Cephalopelvic disproportion because ofmalpresentation or abnormal pelvic bone structure•Active genital Herpes infection•Invasive cervical carcinoma•Hypersensitivity to cervical ripening agentsTransverse lie
Conditions where IOL is not a true contraindicationbut where special caution is required :•Multiple pregnancy•Polyhydramnios•Grand multiparity•Maternal heart disease.•Severe hypertension.• Breech presentation•One or more previous cesarean section•Abnormal fetal heart rate not requiring emergencycesarean section
Risks of IOL:Maternal Risks :•Failure leading to Cesarean section•Uterine hyperstimulation•Rupture uterus•Intrauterine infection, Chorioamnionitis•Amniotic Fluid Embolism•Precipitate labor , Dysfunctional labor•Increased risk of operative vaginal delivery•Increased risk of post partum hemorrhage•Abruptio Placentae•APH from undiagnosed placenta praevia•Water intoxication
Fetal Risks :•Fetal distress .•Fetal death•Neonatal sepsis•Iatrogenic delivery of a preterm infant•Cord prolapse•Neonatal jaundice•Increased risk of birth trauma
Pre- requisites for IOL:•Evaluate the indication•Explain the indication of induction to the patient along with details ofthe method to be used and take a written informed consent•Assess adequacy of the pelvis and fetal size•Confirm the gestational age, fetal lie, and assess the fetal lung maturity# where ever indicatedUterine activity and fetal heart rate should be continuously monitored.In case of clinical auscultation, FHR should be heard during and for 30seconds after a contraction at least every 15 minutes during the activephase of labor and after every contraction in the second stage .Otherwise electronic fetal monitoring is preferable· Partogram is to be maintained for active labour· Trained personnel and well equipped center
# According to the ACOG Committee Opinion (2) , if one of the followingcriteria are met then fetal maturity may be assumed and amniocentesisneed not be performed to confirm fetal maturity:- Fetal heart tones have been documented for 20 weeks by non electricfetoscope or for 30 weeks by Doppler- It has been 36 weeks since a positive serum or urine human chorionicgonadotropin pregnancy test was performed by a reliable method- An ultrasound measurement of the crown rump length, obtained at 6-11 weeks,supports a gestational age of 39 weeks or more- An ultrasound scan obtained at 12 to 20 weeks confirms thegestational age of 39 weeks or more determined by clinical history andphysical examination
Structures of the cervix and Physiology of cervical ripening :The uterine cervix has broadly two components which are:a) cellular portion and,b) extracellular matrixThe distal portion has greater connective tissue as compared to the partclose to the myometrium which is richer in the cellular component.The cellular component has: smooth muscle cells, fibroblasts,epithelium, and blood vessels. Cervical stromal cells producecollagenases, elastases and metalloproteinaeses which are involved inremodeling of the cervix. Fibroblasts also secrete cytokines likeinterleukin 1 beta and interleukin -8
Extracellular matrix is composed of :a) Collagen: collagen is in two forms Type I (70%) and type II(30%) and is arranged in the form of a triple helix. In the nonpregnant cervix these are arranged in a dense and irregularfashionb) Elastin: these fibres are arranged parallel to and betweenthe collageAn fibres and play an important role in taking thepregnancy to term by keeping the os closedc) Decorin: is a glycosaminoglycan and its relative proportionto collagen is important in the remodeling of the cervix atlabord) Hyaluronic acid: is the most important proteoglycan whichis responsible for the increased water content of the cervix
Changes during pregnancy:a) Collagen is reorganized and consolidated in early pregnancy withproliferation and hyperplasia of the cellular componentb) Near the onset of labor, an overall decrease in the concentrationof collagen occurs with dispersion and remodeling into fine fibres ,making the cervix softer in consistencyc) Increases in decorin levels and physiologic cell death are in partresponsible for this processd) Hyaluronic acid levels increase thereby increasing the watercontent of the cervix and causes a loosening and dispersal of the fibrese) Chemotactic response at term leads to an influx of neutrophilsand an increased levels of cyokines (interleukin 1 beta and interleukin –8 ) which in turn release collagenases and elastases to allow effacementf) Mechanical forces of uterine contractions extend the elastin andallow dilatation
PRE INDUCTION CERVICAL ASSESSMENT:It is known that success of labor induction is closely related toripeness of the cervix . Various scores have been proposed toevaluate the cervical status.a) Bishop’s Score : This was proposed by Bishop in 1964 (3)and is the most widely used score. It was originally proposedto determine the suitability of a patient for IOL in patientswho were parous, at term , had an uncomplicated pregnancyand the fetus was in cephalic presentation.
Table 1. Bishop Score for Assessing Favor ability for Induction of labour. ScoreFactor 0 1 2 3Dilatation (cm) 0 1-2 3-4 5-6Effacement(%) 0-30 40-50 60-70 80Station -3 -2 -1 or 0 +1 or +2Consistency Firm Medium Soft -Position Posterior Mid Anterior -* A score of 9 or more ensured a safe and uniformly successful induction
* Induction with a score of 16 more is consideredfavorableBurnett (5) later on modified the original Bishop’sscore giving a maximum score of 2 to each ofBishops five categories, giving a total maximumscore of 10. He considered effacement in terms of length andnot percentage and considered previous term birthand cephalic presentation to be pre-requisites forinduction.
* Outcome of patients with a score of less than 6 was unfavorable, with a score of 9-10 all patients could be delivered within 4 hours and most within 24 hours.Evaluating the performance of Bishops score, Lange et al (6) observed that cervicaldilatation was twice as important as the other factors and proposed a modification ofthe original score which predicted successful induction equally well.
Table 4. Pelvic Score Proposed by Lange et al ScoreFactor 0 1 2 3 Multiply byDilatation (cm) 0 1-2 3-4 >4 X2Length (cm) 3 2 1 0 X1Station(cm) -3 -2 -1 or 0 +1 or +2 X1
METHODS OF CERVICAL RIPENING AND LABORINDUCTION: Cervical priming before labor inductionin an unfavorable cervix increases the success ratesand shortens the induction to delivery interval. Methods for cervical ripening and labor induction canbe broadly classified as :•Pharmacological methods (Prostaglandins, Oxytocin& others)•Non pharmacological methods (Natural, Surgical ,Mechanical and others)
PHARMACOLOGICAL METHODSPROSTAGLANDINS :PG E2 gel has been widely used for pre-inductioncervical ripening. Local applications of PGE2 causescervical ripening by three mechanisms:•Alteration of extracellular grounds substance ofcervix by increasing collagenase , elastase,glycosaminoglycans , dermatan sulfate, andhyaluronic acid levels•Relaxation of smooth muscle of cervix•Gap junction formation leading to initiation ofuterine contractions
Preparations available, Dosage and Usage Guidelines :Intracervical PGE2 gel: ( Cervigel , Dinoripe , Prepidil )•Contains 0.5 mg of PGE2•Bring the gel to room temperature before use and instill inthe cervical canal below the internal os•The patient lies supine for 15-30 minutes after the insertion .•If no response occurs in one use a repeat insertion may berequired after 6 hours•Maximum of 1.5 mg or three insertions are allowed over aperiod of 24 hours.•If required oxytocin is to used only after 6- 12 hours of thelast insertion.
Intravaginal PGE2 gel:•Vaginal PG E2 gel : - contains 2.5 mg PGE2 - 2 doses 6 hours apart are used•Vaginal controlled release insert : (Cervidil )- 10 mg insert which releases 0.3 mg / hr of theprostaglandin- No need to pre warm the insert .- The patient should lie supine for 2 hoursfollowing the insertion- The insert is to be removed after 12 hours orwhen active labor begins or in case ofhyperstimulation.
PGE 2 Routes : Controlled trials : Some observations (10-13)•Intracervical use is technically more difficult•Vaginal route ( gel or insert ) is superior to intracervical route forcervical ripening but it causes higher uterine activity•Controlled release vaginal insert use gives a better post ripening score,decreased the time to delivery, time to active labor and need foroxytocin use as compared to vaginal gel 2 doses 2.5 mg six hours apart.•The overall incidence of hyperstimulation is 4.8% - same as withoxytocin. However , the incidence is more when used in active labor(12.5 %) , more with vaginal gel (5%) than intracervical (1%) and leastwith controlled release insert which can be reversed with terbutalineadministration or removal of the vaginal insert. Washing the vagina doesnot offer any benefit .•Use of PGE 2 does not alter C. S. rates
Contraindications:Established uterine activity, glaucoma, asthma,severe hepatic or renal impairment , knownhypersensitivity to prostaglandins , activevaginal bleeding
Side EffectsUterine tachysystole has been reported to follow vaginally administeredprostaglandin E2 in 1 to 5 percent of women . Although definitions may varyamong studies, most use the terms defined by the American College ofObstetricians and Gynecologists (1999a) to describe increased uterine activityas follows:1.Uterine tachysystole is defined as 6 contractions in a 10-minute period.2.Uterine hypertonus is described as a single contraction lasting longer than 2minutes.3.Uterine hyperstimulation is when either condition leads to a nonreassuringfetal heart rate pattern.Because hyperstimulation that can cause fetal compromise may develop whenprostaglandins are used with preexisting spontaneous labor, such use is notrecommended. If hyperstimulation occurs with the 10-mg insert, its removal bypulling on the tail of the surrounding net sac will usually reverse this effect.Irrigation to remove the gel preparation has not been helpful.
ACOG Guidelines : (14,15)Bishop’s score should be less than 4. Drug should beadministered near the delivery suite. Patient should lierecumbent for 30 minutes after the instillation. FHR anduterine activity should be monitored for 30 minutes to 2hours after the instillation. After this , patient may betransferred elsewhere, if there is no increase in uterineactivity and FHR is normal. The controlled release insertshould be removed at the onset of labor. Oxytocin should beavoided for initial 6-12 hours
RCOG Guidelines : (16)Intravaginal PGE2 should be used in preference tointracervical preparations as they are equally effectiveand administration of intravaginal PGE 2 is lessinvasive of the vaginal preparations. Tablets should bepreferred over the gel as they are more cheap andequally effective.
MISOPROSTOL:Mioprostol is a synthetic PG E1 analogue which hasbeen used as a gastric cytoprotective agent since1988 for patients of peptic ulcer. Studies in late 1980’s and early 1990’s noted that oraladministration of this drug causes uterinecontractions in early pregnancy. Subsequent studiesshowed that intravaginal misoprostol causes first andsecond trimester abortion and there has been recentevidence of its use for cervical ripening and laborinduction.
Pharmacokinetics: The pharmacokinetics of misoprostolhave been extensively studied by Ziemann etal (17). They have observed that peak plasma concentration ishigher and achieved earlier after an oral administration. Peaklevels with vaginal administration are attained more slowlyand sustained for longer periods because of the presystemicgastrointestinal and hepatic metabolism that occurs with oralroute . Overall the systemic bioavailability is three times higherwith the vaginal route.
Dosage schedules and usage guidelines:•Cheap drug•Does not require storage conditions•Can be given by oral, buccal or vaginal routesalthough vaginal route is the most extensively used•Tablets are available as either 100 mcg or 200 mcg•Dosage: 25 –50 mcg is administered 4-6 hourly•The tablet is inserted into the posterior vaginalfornix , one may or may not wet the tablet with salineprior to insertion
Misoprostol : Controlled trials : some observations: (18)•Oral route is not recommended at this point of time•Misoprostol shortens the Induction delivery interval ascompared to PG E2 and oxytocin•25 mcg vaginal dose has less hyperstimulation but a longerIDI as compared to 50 mcg•It effectively lowers the cesarean rates•However it is not recommended as an outpatient setting orwith previous C. S.•An increase in the incidence of meconium staining of amioticfliud and tachysystole is noted•Overall the use of misoprostol is not associated with anincreased rate of operative intervention for fetal distress andNICU admission.
ACOG Guidelines25mcg should be the initial dose for labor induction at term , should notbe administered more frequent than 3-6 hours , oxytocin should not beadministered < 4 hours after the last misoprostol use and the drugshould be avoided in patients with previous cesarean delivery or majoruterine surgery.Use of higher dosage 50 mcg may be appropriate in some situationsand have a greater likelihood of vaginal delivery within 12 hours, suchdoses increase the risk of hyperstimulation and rupture.There is at present insufficient clinical evidence to address the safety ofmisoprostol in patients with multiple gestations and suspected fetalmacrosomia.
RCOG Guidelines : (16)Misoprostol appears to be more effective than oxytocin or vaginal PG E2in presence of ruptured membranes for induction of labor.Use of misoprostol in obstetrics must be restricted to RCTs.Oral misoprostol appears to be less effective than vaginal misoprostol,however, oral route is associated with less incidence of uterinehypercontractility but a higher incidence of meconium stained liquor. Its use is associated with increased uterine hypercontractilty but this isnot translated in increased operative delivery rates. The safety issuessurrounding the use of misoprostol have not been clearly evaluated.* Despite a lot of clinical use, misoprostol is still not approved by theDrug Controller of India for use in induction of labor.
OXYTOCIN:Oxytocin is a polypeptide hormone secreted from theposterior pituitary gland which acts as a potent uterotonicagent. The drug was used intravenously in 1948 by Theobaldet al (21) to induce labor. Later in 1958 Du Vigneaud et al (22)synthesized the drug. Since then it has been the mostcommonly used drug for induction and augmentation oflabor.Routes of administration:Oxytocin can be administered by any parenteral route,intravenous route being the most widely used. It can beabsorbed from the nasal or buccal mucosa, however whengiven orally it is rapidly inactivated by trypsin.
Pharmacokinetics and mechanism of action:The half life of oxytocin is 3-5 minutes. Once absorbed it is distributed in theextracellular fluid and does not bind to plasma proteins and is excreted by the liverand kidneys.The action is mediated by oxytocin receptors (OTR) which are present on themyometrium.Myometrial response to oxytocin begins at 20 weeks , increases through outpregnancy and peaks just before initiation of labor.The response varies according to the status of the cervix, uterine sensitivity, variabilityin oxytocin clearance rate, duration of pregnancy and the pre-existing myometrialcontractions.The OTR concentration is the rate limiting step for oxytocin action. Oxytocin onbinding to the OTR increases the intracellular concentration of calcium causingmyometrial cell contraction. Uterine contractions are also stimulated by a calciumindependent mechanism involving the prostaglandins. PGE and PGF are increasedduring oxytocin administration. It has been postulated that Prostaglandin release byoxytocin is necessary for fully efficient uterine contractions during labor.
Dosing and Usage Guidelines:10 –20 units are dissolved in 1000 ml of balanced salt solution ( Ringer Lactate solutionor Normal saline ) making it as 10-20 mu/ml and it is preferable to give it through aninfusion pump. Further increments are made according to the low dose or high doseprotocol given below (15 ) :Regimen Starting dose Incremental dose Dosage interval (mU/ min) (mU/ min) ( min)Low Dose 0.5 – 1 1 30-40 1 –2 2 15High dose 6 6 15 6 6, 3*, 1* 20-40* The incremental increase is reduced to 3 mU/min in presence of hyperstimulationand reduced to 1mU/min with recurrent hyperstimulation .
After intravenous infusion , uterine response occurs within 3-5 minutes and a steady state plasma concentration is reachedin about 40 minutes.The end point to be achieved is uterine contractions every 2-3 minutes lasting for 60-90 seconds and a uterine pressure of50- 60 mm Hg or 150 Montevideo units.
Risks of Oxytocin:· Hyperstimulation , with or without fetal heart ratechanges· Failed induction with need for repeat induction orpossibly cesarean· Increased risk for uterine rupture in some studies· Hypotension if administered by IV bolus· Hyponatremia if administered with large amounts ofsodium poor fluids· Antidiuretic hormone like effect if administered at highdoses· Increased risk for neonatal hyperbilirubinemia
In the management of active-phase arrest, and withno contraindication to intravenous oxytocin,decisions must be made with knowledge of the safeupper range of uterine activity. Importantly, despite no labor progression, therewere no adverse maternal or perinatal effects inthose undergoing cesarean delivery.There are no data regarding safety and efficacy ofcontraction patterns in women with a prior cesareandelivery, with twins, or with an overdistended uterus.
Duration of OxytocinAdministration—Active PhaseArrestFirst-stage arrest of labor is defined by the AmericanCollege of Obstetricians and Gynecologists (1989,1995a) as a completed latent phase along withcontractions exceeding 200 Montevideo units formore than 2 hours without cervical change. Someinvestigators have attempted to define a moreaccurate duration for active-phase arrest.
Rouse and colleagues (1999) prospectively managed 542women at term with active-phase arrest and no othercomplications.Their protocol was to achieve a sustained pattern of atleast 200 Montevideo units for a minimum of 4 hours.This time frame was extended to 6 hours if activity of 200Montevideo units or greater could not be sustained.Almost 92 percent of these women were deliveredvaginally.These and other studies support the practice to allow anactive-phase arrest of 4 hours (Rouse and associates,2001).
How do we calculate uterineactivity ?MONTEVIDEO UNITS :No of contractions / 10 MIN XAvg, intensity of contractions in mm of hg Eg : 3 X 60mmHg = 180Uterine activity – Spontaneous labour - 200 MVs Induction of labour - 250 – 275MVs
RCOG Guidelines : (16)· Oxytocin should not be started for 6 hours followingadministration of vaginal prostaglandins· In women with intact membranes , if feasibleamniotomy should be performed prior to commencement ofoxytocin infusion· Minimum possible dose of oxytocin should be used andtitrated against uterine contractions. Maximum licensed doseis 20 mU/min and should not be exceed 32 mU/min· Local protocols should specify the dose , dilution ofoxytocin and preferably be delivered via infusion pump orsyringe driver with non-return valve
Infusion pumps is an electronic apparatus designed todeliver drugs and biologicals, at low doses.The delivery process of these pumps are associated withlocal hemolysis which consists the potential benefits of acalibrated delivery system.infusion pumps are easy to use as these are designedkeeping in mind the requirements of patrons at ourvendors end.
Oxytocin Administration via the Infusion Pump1. Oxytocin for the purpose of induction or augmentation of labor, will be ordered by thephysician and administered by an RN.2. Oxytocin administered for induction or augmentation of labor will be performed only inL&D after a minimum 30 minute baseline FHR and UA tracing is obtained.3. A registered nurse is responsible for the operation of the pump (adjustments to infusionrate per MD order).4. Continuation of an oxytocin infusion beyond 20 milliunits/min requires an MD order.5. In accordance with ACOG recommendations, the practice of elective* delivery prior to39 weeks gestation is prohibited (unless approved by Chairman/Clinical Chief).*An elective delivery is a delivery prior to 39 weeks gestation without a valid medical or
CONTRA-INDICATIONS:Contraindications include but are not restricted to:1. Unfavorable fetal positions2. Uterine tachysystole3. Hypersensitivity to the drug4. Cases where vaginal delivery is contraindicated, such ascomplete placenta previa, vasa previa, and cord prolapse
EQUIPMENT:Infusion pumpPremixed 500ml bag of D5W with 20units of oxytocinInfusion pump tubing
PROCEDURE:ACTION1. Place patient on external electronic fetal monitor to establish a continuous fetalheart rate (FHR) tracing and uterine activity (UA) pattern.2. The determination of cervical dilation, effacement, station and position should beperformed either prior to the initiation of the infusion or within the first 2 hoursafter the initiation of the infusion.3. Assist with the placement of internal fetal monitoring and intrauterine pressurecatheters when ordered by3. Provide additional information regarding fetal status and uterine contractions.
4. Piggyback oxytocin infusion to main IV line as close to venipunture as possible. It may be necessary to remove or adddifferent IV tubing so the oxytocin can be placed close to the venipuncture site.4. Piggybacking the solution away from the venipuncture site can result in an oxytocin bolus.5. Program infusion pump. Select Intrapartum pitocin concentration (20 units oxytocin in 500 ml)6. Confirm pitocin concentration.6. Concentration is 40 milliunits/ml.7. Select dose in milliunits/min.8. Enter the volume to be infused.9. Begin infusion at 2 milliunits/min and increase by 2 milliunits/min every 30 minutes or as ordered by the physician until anadequate labor pattern is established. When the infusion rate reaches 20 milliunits/min notify the physician.9. Continuation of the infusion beyond 20 milliunits/min requires a physician’s order.
10. Decrease oxytocin if:Tachysystole is presentThe uterine resting tone is increased by palpation assessment or Intrauterine Pressure Catheter(IUPC)For fetal heart rate tracing concerns as assessed by nurse or physician. MD should be notified.11. Discontinue oxytocin if:Uterine tetanyFetal indications as assessed by nurse or physician10. Notify physician.12. If restarting oxytocin is indicated, begin with the following guidelines:If the oxytocin was discontinued for less than 30 minutes because of:Uterine tachysystole restart oxytocin 4 milliunits/min lower than the previous level
Fetal indications: restart oxytocin at 2.0 milliunits/min or at thediscretion of the physicianIf the oxytocin discontinued for more than 30 minutes, restart at 2.0milliunits/min or at the discretion of the physician
Other Pharmacological methods:a) Mifepristone: 200 mg misoprostone for 2 days has been recently used forcervical priming (23). However this method is not cost effective and needs furthertrials.b) Relaxin : Relaxin has been demonstrated to causes changes in the collagenresulting in cervical softening . Both purified porcine and DNA produced human relaxinhave been tried with success in promoting cervical ripening with no adverse maternaland fetal outcomes (24,25) . It is not yet commercially available.c) Nitric Oxide: Animal studies have shown it to be a cervical ripening agent but it isunlikely to be used for human use unless safety of NO in late pregnancy is establishedd) Cytokines: Theses are chemotactic agents which also can promote cervicalripening by causing changes in the extracelllulaar matrix
NATURAL MODALITIES:a) Herbal supplements: Commonly used herbal cervical ripeningagents include evening primrose oil, black cohosh, raspberry leaves. Theliquid of black cohosh is given as 10 drops sublingually hourly until thecervical change occurs. Evening primrose oil is given as 3 capsules orallydaily for one week, this can be repeated for three such administrations..red raspberry leaves also enhance uterine contractions in a synchronousmannerb) Intercourse : results in a 10-50 fold increase in cervical mucusprostaglandin concentrationswhich occurs after 2-4 hours and remainsfor more than 12 hours duration . There is an associated increase inthe uterine contractile activity .
SURGICAL METHODS:AMNIOTOMY: Ideally amniotomy or ARM is performed when the cervix is effacedand 2 cm dilated but it can be performed with minimal cervical dilatation.Methodology of ARM:•Auscultate the FHR•Evaluate the cervix and station of head. The cervix should be well applied to the head•Introduce two fingers into the cervix , sweep away the membranes from the cervix•Pass an Allis or Kocher’s forceps in between the groove of your two fingers , hook themembranes and rupture them ; look for the clarity of liquor•Risks: Cord prolapse FHR deceleration Bleeding through vasa praevia Fetal injury Maternal and fetal infection Advantages: - It shortens duration of labor - Allows for early diagnosis of meconium staining of amniotic fluid,speciallyin high risk pregnancy - Facilitates invasive fetal monitoring
MECHANICAL MODALITIES:a) Hygroscopic dilators: These are natural or synthetic rods insertedthrough the cervical os and left in situ for a particular time whereinbecause of their osmotic properties they absorb endocervical and localtissue fluids . This swelling causes a controlled dilatation of the cervixalong with releasing prostaglandins. Natural dilators are obtained fromthe seaweed Laminaria japonicum.b) Balloon devices : Foley’s catheter or designer balloon deviceswhen inserted intracervically can facilitate cervical ripening. Onceproperly placed ( beyond the internal os) balloon or the catheter isinflated with 30-50 ml saline. It is recommended to either attach adefined weight to the catheter end ( 1litre of i.v. fliud ) or to use “gentletugs” – 2 to 4 each hour until the catheter or the balloon passes out(26,27) . Some recommend infusion of extra-amniotic saline at the rateof 1 cc/minute. There is no infection associated with balloon devices
MISCELLANEOUS:a) Castor Oil (28 ) : It is an extract from “Ricinus communis”and is mainly crude ricinoleic acid .It is known to stimulate gutperistalsis and labor most likely is stimulated due to release ofprostaglandins. The method is no longer used now. One studyhas reported an increased incidence of meconium staining ofamniotic fluid.b) Accupuncture and TENS( Transcutaneous electric nervestimulation) : Few studies ( 29-31) have reported successfulinduction of labor with these methods but further trials areneeded before planning a large scale use.
CERVICAL RIPENING AND IOL IN SPECIALCIRCUMSTANCES:a) Previous C. S. :· One or more previous C. S. are not acontraindication to the induction of labor.· Cervical ripening can be done in these situationswith PGE2 gel – either intravaginal or intracervical· Misoprostol is an absolute contraindication· Oxytocin can be safely used in low doses withclose monitoring of uterine contractions and FHR.· It is preferable to have continuous electronicfetal monitoring.
b) Twin pregnancy:· PGE 2 gel can be safely used for cervical ripening· ARM facilitates induction· Oxytocin in low doses can be usedc) Premature rupture of membranes (PROM) :· Use of PGE2 gel– 2 doses 6 hours apart is not associated withhigher incidence of infection· Misoprostol can also be used in 25 mcg dose· Oxytocin infusion should be closely monitored· Beware of hyperstimulation
d) Intrauterine fetal demise (IUFD ) :· Oxytocin is effective for IOL near term with afavorable cervix.· All prostaglandins can safely be used inrecommended dosages for cervical ripening remotefrom term.
Induction of labor : Summary of evidence based ACOGrecommendations:Recommendations based on good and consistent scientific evidence (Level A) Prostaglandin E analogues are effective in promoting cervicalripening and inducing labor Women in whom induction of labor is indicated may beappropriately managed with either a low or high dose oxytocin regimen Fetal heart rate and uterine activity should be continuouslymonitored from the time the PGE 2 vaginal insert is placed until at least15 minutes after it is removed High dose PGE 2 vaginal suppositories may be used in themanagement of intrauterine fetal demise in the second trimester ofpregnancy Although the optimal dose and timing interval of misoprostol isunknown , lower doses ( 25 mcg every 3-6 hours) are effective forcervical ripening and induction of labor
Recommendations based on evidence that maybe limited or inconsistent ( Level B): Misoprostol use in women with priorcesarean birth should be avoided because ofthe possibility of uterine rupture The use of higher doses of misoprostol (50 mcg every 6 hours) to induce labor may beappropriate in some situations , although thereare reports of increased risk of complications,including uterine hyperstimulation.
Recommendations based onconsensus and expertopinion ( Level C) : For women with third trimester intrauterinefetal demises, intravaginal misoplrostol can be used toinduce labor. Fetal heart rate and uterine activity should becontinuously monitored from 30 minutes to 2 hoursafter administration of PG E2 gel
Failure of InductionIt is defined when Cx failed to dilate up to 3-4 cm in 24 hrs ofinduction.What to do now ? - Option to wait-- if No PROM and postponement is notharmful for fetus as well as mother. - Review the case and if there is urgency, Caesareandelivery is performed.
Whats new in monitoring of labour ?MONITORING UTERINE CONTRACTIONS : Intra uterine pressuresFETAL MONITORING Fetal pulse oximetry Fetal electrocardiogram wave form analysis Intermittent measurement of lactate by FBS As an adjuvant to EFM as it has high False positive rates