Induction of labor

INDUCTION OF LABOR (Medical & Surgical

Methods)PRESENTATION BY:

Dr Mansi Gupta

SOME IMPORTANT TERMS• INDUCTION- stimulation of contractions before the spontaneous onset of labor, with or without ruptured membranes.

•AUGMENTATION- increasing the frequency & improving the intensity of existing uterine contractions in a patient who is in labor & not progressing adequately, in order to accomplish vaginal delivery.

•EARLY PRETERM- before 33+6wks•LATE PRETERM- 34 to 36+6wks•EARLY TERM- 37 to 38+6wks•TERM- 39 to 40+6wks•POST TERM- beyond 42 wks•41-41+6wks - dilemma

•INDICATIONS????

INDICATIONS • ABSOLUTE INDICATIONS1. Hypertensive disorders- eclampsia/preeclampsia2. Maternal medical conditions- DM, Renal dis, Chronic pulmonary

dis3. PROM4. Chorioamnionitis5. Fetal compromise ( IUGR, Isoimmunisation, NRFHR,

Oligohydroamnios)6. IUD7. Posterm pregnancy(>42wks)

•RELATIVE INDICATIONS1. Hypertensive disorder( Chronic HTN)2. Maternal medical condition- SLE, GDM,

Hypercoagulable dis, ICP3. Polyhydroamnios4. Fetal anomalies req specialised neonatal care5. Logistic factors- Risk of rapid labor, distance from

hospital, psychosocial; indications, Advanced cervical dialation

6. Previous stillbirth7. >41wks

CONTRAINDICATIONS?????????

CONTRAINDICATIONS ABSOLUTE MATERNAL CONTRAINDICATIONSActive genital herpesSerious chronic medical conditionsMajor degree cephalopelvic disproportion (such as women with pelvic deformities)FETAL CONTRAINDICATIONSMalpresentation (transverse or oblique lie)Extreme fetal compromiseUTEROPLACENTAL CONTRAINDICATIONSCord presentationPlacenta previa Vasa previaClassical caesarean section, prior high vertical hysterotomy or myomectomy entering endometrial cavity

RELATIVE CONTRAINDICATION

•Cervical carcinoma•Malpresentation•Grand multiparity•Uterine overdistension (secondary to polyhydramnios)•Fetal macrosomia•Low lying placenta•Unexplained vaginal bleeding

WHAT IS ELECTIVE IOL???

•ELECTIVE IOL

Initiation of labor for convenience, in an individual with a term pregnancy who is free of medical or obstetric indications.

Although not recommended or encouraged, it may be appropriate in specific instances such as 1. H/O very short labors2. Pt who lives far from hospital

RISK- Increased Caesarean( sp in nulliparous), Iatrogenic prematurity

• A recent meta-analysis included 16studies that compared induction and expectant management for uncomplicated singleton pregnancies of at least 41weeks gestation. Compared with women allocated to expectant management , those who underwent labor induction had lower caesarean rates. There were no satistically significant differences in perinatal mortality rates, NICU admissions, MSL, abnormal APGAR. Therefore after 41wks,elective labor induction appears to be justified.(gabbe)

• The trials had evaluated the effect of inducing labour at 37–40 weeks, 41 completed weeks, and 42 completed weeks of gestation, and the intervention was compared with expectant management with fetal monitoring at varying intervals. There were no statistical and clinical differences in the priority comparisons and outcomes, except for a reduction in perinatal deaths when labour was induced at 41 completed weeks.(WHO)

Induction of labour in women at or beyond term (WHO)• Recommendations 1. Induction of labour is recommended for women who are known with certainty to have reached 41 weeks (> 40 weeks + 7 days) of gestation. (low-quality evidence. Weak recommendation.) 2. Induction of labour is not recommended for women with an uncomplicated pregnancy at gestational age less than 41 weeks. (low-quality evidence. Weak recommendation.)

• Remarks 1. Recommendation no. 1 above does not apply to settings where the gestational

age cannot be estimated reliably.2. There is insufficient evidence to recommend induction of labour for uncomplicated pregnancies before 41 weeks of pregnancy.

Induction of labour in women with GDM (WHO)

• Recommendation 1. If gestational diabetes is the only abnormality, induction of labour

before 41 weeks of gestation is not recommended. (very-low-quality evidence. Weak recommendation.)

• Remark 1. Participants in the WHO technical consultation acknowledged that labour induction may be necessary in some women with diabetes – for example, those with placental insufficiency and uncontrolled diabetes.

Induction of labour for suspected fetal macrosomia(WHO)• Recommendation 1. Induction of labour at term is not recommended for suspected fetal macrosomia

(low-quality evidence. Weak recommendation.)

• Remark 1. Confirmation of suspected macrosomia is based on reliable determination of fetal age and weight, which requires ultrasound assessments early in pregnancy and then at near term. considering that in under-resourced settings ultrasound facilities may not be available or accessible to all women, the participants in the technical consultation preferred not to recommend induction of labour for suspected macrosomia, even though they acknowledged that in cases of confirmed macrosomia induction of labour could reduce the incidence of clavicle fracture due to shoulder dystocia.

Induction of labour in women with prelabour rupture of membranes at term (WHO)• Recommendation 1. Induction of labour is recommended for women with prelabour rupture of

membranes at term. (High-quality evidence. strong recommendation.)

• Remark 1. Participants in the WHO technical consultation noted that in the trials included in the cochrane review, induction of labour had been initiated within 24 hours of rupture of membranes. They also noted that oxytocin should be regarded as the first option for induction of labour in women with prelabour rupture of membranes.

Induction of labour in women with uncomplicated twin pregnancy at or near term (WHO)

•Recommendation 1. none.

•Remark 1. The participants in the technical consultation noted that there was insufficient evidence to issue a recommendation on induction of labour in women with an uncomplicated twin pregnancy at or near term.

•About 70% of twin & higher multiple pregnancies deliver between 35 & 37 weeks spontaneously reducing the need for elective induction at 38 wks

•Some necessitate early delivery due to early onset complications such as growth restriction, PET, where decision has to be individualized depending on severity of complication. No data is available to assess the safety of induction before 37 weeks

HEART DISEASE• There is little place for induction in heart disease because 1.it may misfire & a prolonged induction delivery interval may result in infection or caesarean section2.Anxiety due to induction may lead to worsening of heart disease3.Risk of fluid overload & failure• PGE2 can be used for cervical ripening but as it is a potent vasodilator

& causes marked rise in cardiac output,it can lead to pulmonary edema.• Amniotomy is generally deferred for fear of ascending infection

(chorioamnionitis)• NOTE: restrict I/V fluids to 75cc/hr

Breech presentation• Induction of labour is not generally recommended if a

woman’s baby is in the breech presentation.

• If external cephalic version is unsuccessful, declined or contraindicated, and the woman chooses, not to have an elective caesarean section, induction of labour should be offered, if delivery is indicated, after discussing the associated risks with the woman.

IUGR ( RCOG)•When end diastolic flow is present , IOL at 37 week ,

provided other surveillance findings are normal•When end diastolic flow absent or reverse : • -Gestation> 34 weeks then IOL , if other surveillance

tests are normal [ BPP/CTG, Venous doppler ]• -Gestation < 34 weeks then admission , close

surveillance , steroids • If other surveillance tests abnormal- delivery by CS

Hypertensive disorders of pregnancy (gabbe)•GESTATIONAL

HYPERTENSIONMild increased risk of abruptio placenta•MILD PRE-ECLAMPSIADisease progression follows no predictable patternIncreased chances of HELLP syndrome

Both oxytocin and PGs can be used

• SEVERE PREECLAMPSIA -IOL at 34 weeks If < 34 weeks -pregnancy can be continued beyond 24 hours if patient is stabilised . Consider steroids.

IUFD[1]Combination Mifepristone and Misoprostol -200mg Mifepristone 24-48 hours before induction -Vaginal Misoprost - 100ug 4 hourly X 4 doses • If POG >28 wks – 50ug 4 hourly X 4 doses[2] Vaginal Misoprostol - 13-17 wks 200ug 6 hourly X 4 doses - 18-26 wks 100ug 6 hourly X 4 doses - > 27 wks 25-50ug 4 hourly X 6 doses

STABALISING INDUCTION??

STABILISING INDUCTION• Describes when the presenting part is not within the pelvis• This follows an external version for a transverse or oblique lie but

may also be undertaken with a longitudinal lie & a high head• Indication must be critically reviewed to ensure requirement of

delivery immediately• If delivery cannot be delayed, an infusion of oxytocin should be

commenced prior to amniotomy to ensure that contractions have commenced & head is over brim• Then the head is fixed by an assistant and controlled ARM is done • NOTE: there are high chance of cord prolapse, & facilities for

immediate caesarean section should be available

EVALUATION BEFORE IOL • MATERNAL1.Confirm indication 2.Review contraindication3.Perform clinical pelvimetry4.Assign bishop score5.Review risks, benefits and alternatives of IOL with pt.

• FETAL/NEONATAL1.Confirm POG2.Assess need to document fetal lung maturity status3.EFW4.Fetal lie & presentation5.Confirm fetal well-being

CERVICAL SCORING SYSTEM• Cervix assessed by digital vaginal examination prior to induction, with the aim to

gauge the ease with which induction will be achieved• Cervical scoring was first described by Bishop in 1964, when he showed inverse

relationship between cervical score & time taken for the woman to be in established labour • Various modifications of Bishop’s original score have been suggested, & most

widely used is Calder’s modified Bishop score• Scores below 6 show unfavourable cervix, where natural process of ripening has

not yet begun• In women with scores above 6, artificial rupture of membrane is usually simple &

becomes a possible method of inducing labour, although ripening agents may still be administered• If the total score is more than 8,the probability of vaginal delivery after labour

induction is similar to that after spontaneous labour.

BISHOP’S SCORE (BISHOP 1964)

• TOTAL SCORE:13, FAVOURABLE SCORE 6-13, UNFAVOURABLE SCORE 0-5

MODIFIED BISHOP SCORE (CALDER 1974)

• TOTAL SCORE: 12, UNFAVOURABLE 0-5, FAVOURABLE 6-12

FACTORS FOR SUCCESSFUL IOL???

FACTORS FOR SUCCESSFUL IOL 1. POG- near term2. Bishop score - >=63. Cervical ripening- favourable in parous and PROM4. BMI <305. Birth weight <3.5kgs6. Presence of fetal fibronectin in vaginal swab-

>50ng/ml7. Senstivity of uterus- positive oxytocin senstivity

PREINDUCTION CERVICAL RIPENING•Enhancing the cervical favorability by different pharmacological and mechanical methods.•Some of the techniques described may have benefits when compared with oxytocin induction alone. Some are also quite successful for initiating labor. That said, few data support the promise that any of these techniques results in a reduced cesarean delivery rate or in less maternal or neonatal morbidity compared with that in women in whom these methods are not used.

METHODS OF IOL PHARMACOLOGICAL METHODS MECHANICAL METHODS

1.OXYTOCIN

2.PROSTAGLANDINS E2- Dinoprostone, Prepidil gel and Cervidil time-released vaginal insert E1- Misoprostol, Cytotec

3. ESTROGEN

4. RELAXIN

5. HYALURONIC ACID

6. PROGESTERONE RECEPTOR ANTAGONISTS- Mifepristone

1. MEMBRANE STRIPPING

2. AMNIOTOMY

3. MECHANICAL DIALATORS- Laminaria tents Dilapan Lamicel

4. TRANSCERVICAL BALLOON CATHETERS- with extra-amniotic saline infusionWith concomitant oxytocin administration

PHARMACOLOGICAL METHODS

OXYTOCIN• PHARMACOLOGY- Nonapeptide hormone Given IV or IM ( orally GI enzymes deactivate it) t ½- 3-6min Duration of action- 20min Steady plasma conc reached in- 30-40min Preserved at- 2-8* C

• MODE OF ACTION-Myometrial oxytocin receptor concentration increases maximum (100-200 fold) during labor. Oxytocin acts through receptor and voltage-mediated calcium channels to initiate myometrial contractions. It stimulates amniotic and decidual prostaglandin production. The uterine contractions are physiological, i.e. causing fundal contraction with relaxation of the cervix. Little change in myometrial sensitivity to oxytocin from 34 weeks to term; however, once spontaneous labor begins, the uterine sensitivity to oxytocin increases rapidly. This physiologic mechanism makes oxytocin more effective in augmenting labor than in inducing labor, and even less successful as a cervical ripening agent.

• PREPRATIONS: (i) Synthetic oxytocin (Syntocinon-Sandoz or Pitocin-Parke-Davis) – only oxytocic effect without any vasopressor action. Ampules - 5 IU/mL.

(ii) Syntometrine (Sandoz)—Syntocinon 5 IU + Ergometrine 0.5 mg

(iii) Desamino-oxytocin— Not inactivated by oxytocinase 50–100 more effective than oxytocin Buccal tablets - 50 IU. (iv) Oxytocin nasal solution- 40 units/mL.

•DOSAGE

1ml amp=5U

1. Conventional low dose regimen= 0.5-1.5 mU/min

2. High dose regimen= 4-6 mU/min

CALCULATION OF DOSE DELIVERED IN MILLIUNITS (mu) & ITS CORRELATION WITH Drops/min

DOSING INTERVAL ?? • Rates of cesarean delivery for dystocia or fetal distress were not

statistically different • 20-minute regimen for augmentation was associated with a

significant reduction in cesarean delivery for dystocia (8 versus 12 percent, P = .05).• Incidence of uterine hyperstimulation was greater with the 20-

minute regimen for induction compared with the 40-minute regimen (40 versus 31 percent; P = .02) . But did not result in an increased rate of cesarean delivery for nonreassuring fetal status. • Neonatal outcomes were unaffected by the dosing interval.

MAXIMAL DOSAGE

Maximal effective dose to achieve adequate contractions in all women is different.

If contractions are not adequate and fetus status is reassuring and labor has arrested, an oxytocin infusion dose >48mU/min has no apparent risks (Williams)

•OBSERVATIONS DURING OXYTOCIN INFUSION1. Rate of flow – counting no. of drops /min

2.Uterine contractions – -no. of contractions/ 10min -intensity of contraction -period of relaxation 3. FHR monitoring4. Asses progress of labor5. Maternal parameters

RISKS 1.UTERINE OVERACTIVITY-Hyperstimulation – • persistent pattern of >4 contractions(WHO) in 10 min• uterine contractions lasting at least 1min(WHO) (hypertonus) or • contractions of normal duration occurring within 1 minute of each other- with or without fetal heart rate changes. Tachysystole - hyperstimulation without FHR changes. Hyperstimulation syndrome - any of above with FHR abnormalities.

1. Uterine tachysystole is defined as > 5 contractions in a 10-minute period. It should always be qualified by the presence or absence of fetal heart rate abnormalities.

2. Uterine hypertonus, hyperstimulation, and hypercontractility are terms no longer defined, and their use is not recommended.

•One of the advantages of oxytocin administration is that if uterine hyperstimulation is encountered, the infusion can quickly be stopped, resolution of such uterine overactivity.•Placing the woman in the left lateral position, administering

oxygen, and increasing intravenous fluids may be of benefit.• If FHR tracing abnormalities persist and uterine

hyperstimulation is ongoing, the use of a tocolytic, such as terbutaline, may be considered. •Oxytocin may then be reinitiated if appropriate once uterine

tone has returned to baseline and fetal status is reassuring.

2. WATER INTOXICATIONOxytocin is structurally and functionally related to vasopressin(ADH). It binds to vasopressin and oxytocin receptors in the kidney and the brain. Oxytocin can have an antidiuretic effect at high doses and can, in extreme situations, result in water intoxication. Severe symptomatic hyponatremia can result if oxytocin is administered at high concentrations (e.g., 40 mU/min) in large quantities of hypotonic solutions (more than 3 liters) for prolonged periods of time.

Symptoms of severe acute hyponatremia include headache, anorexia, nausea, vomiting, abdominal pain, lethargy, drowsiness, unconsciousness, grand mal seizures, and potentially irreversible neurologic injury. Fortunately, this side effect is extremely rare even with high dose oxytocin regimens.

3. HYPOTENSIONHistorically, bolus injections causes hypotension.Current practice for labor management is administration by infusion pump or slow drip. MAP & PVR have been noted to decrease 30% and 50%, respectively, after oxytocin bolus injection of 5 -10U. This caused increases of 30% in HR, 25% in SV, and 50% in CO when compared with patients receiving slow dilute infusions.

However, a more recent reports revealed that a 10-IU bolus of oxytocin given in the third stage of labor was not associated with adverse hemodynamic responses compared with oxytocin given as an infusion.

4. UTERINE RUPTURE

Rare and in most instances occurs in women with prior uterine surgery such as cesarean delivery or myomectomy.

However most studies suggest that the use of oxytocin for labor induction or augmentation in not associated with a significant increase in the risk of uterine rupture in women with a prior cesarean delivery

•INDICATIONS OF STOPPING THE INFUSION1.Tachysystole2.Hypertonus3.Fetal distress4.Untoward maternal symptoms

WHO

•Recommendation 1. If prostaglandins are not available, intravenous oxytocin

alone should be used for induction of labour. Amniotomy alone is not recommended for induction of labour. (moderate-quality evidence. Weak recommendation.)

•Remark 1. Immediately after the initiation of intravenous oxytocin, it is advisable to monitor closely the oxytocin infusion rate, response of the uterus to oxytocin, and fetal heart rate.

PROSTAGLANDINS• Dissolution of collagen bundles and an increase in submucosal water content of the

cervix. These changes in cervical connective tissue at term are similar to those observed in early labor. • PGs are endogenous compounds found in the myometrium, deciduas, and fetal

membranes during pregnancy. Paracrine/autocrine hormones as they act on locally at their site of production. • t1/2 - 1-2min• The chemical precursor is arachidonic acid. • Prostaglandin analogs were originally given by IV and oral routes. Later, local

administration of prostaglandins in the vagina or the endocervix became the route of choice because of fewer side effects and acceptable clinical response. • PGs promote myometrial contraction irrespective of the duration of gestation Side effects of all PG formulations and routes may include fever, chills, vomiting, and diarrhea.

• Caution in-1. Hypersensitivity2. Ruptured membranes3. Glaucoma 4. Asthma5. Patients with compromised cardiovascular, renal & hepatic function

PROSTAGLANDIN E2 1. Gel – Prepidil/Cerviprime—is available in a 2.5-mL syringe for an

intracervical application of 0.5 mg of dinoprostone. With the woman supine, the tip of a prefilled syringe is placed intracervically, and the gel is deposited just below the internal cervical os. After application, the woman remains reclined for at least 30 minutes. Doses may be repeated every 6 hours, with a maximum of 3 doses recommended in 24 hours.

Oxytocin should not be initiated until 6 to12 hours after the last dose.

2.Time-release vaginal insert - Cervidil—is also approved for cervical ripening. This is a thin, flat, rectangular polymeric wafer held within a small, white, mesh polyester sac.The sac has a long attached tail to allow easy removal from the vagina. 10 mg of dinoprostone designed to release approximately 0.3 mg/hr during a 10-hour period. Used as a single dose placed transversely in the posterior vaginal fornix. Lubricant should be used sparingly, if at all, because it can coat the device and hinder dinoprostone release. Following insertion, the woman should remain recumbent for at least 2 hours. The insert is removed after 12 hours or with labor onset and at least 30 minutes before the administration of oxytocin.• Advantage - may be removed with the onset of active labor, rupture of

membranes, or with the development of uterine hyperstimulation.

VAGINAL INSERT- CERVIDIL

3. SUPPOSITORY- 10mg

• Indicated for pregnancy termination between 12 and 20 weeks • Evacuation of the uterus after fetal demise up to 28 weeks.

4. PGE2 ORAL TABLETS (0.5mg)

Almost as effective as oxytocin for inductionUsual regimen is 0.5mg(1 tablet) followed by 1mg (2 tablets) after 1 hour. The successive hourly doses are then adjusted between 0.5 to 1.5 mg according to the patient’s responseThe dose increments are made by 0.5mg, at a time until labour is well establishedIt is abandoned if labour is not established after 8 hoursAdverse effects include vomiting & diarrhoea,fever

5. PGE2 vaginal tablet (3mg)

repeated after 6-8 hrs if requiredRemain lying for 30 minutes after administration

6. PGE2 vaginal gel (1-2mg)

repeated after 6 hrs if requiredStore in refrigerator at 2-8°CRemain supine for 15 mins after administration

PROSTAGLANDIN E1- Misoprostol• Cytotec—is a synthetic prostaglandin E1 that is approved as a 100-

or 200-μg tablet • First used for peptic ulcer prevention. • It is available as 25µg, 100µg, 200µg & 600µg tablets• Route: Oral, vaginal and sublingual route for induction. Rectal route

is used to prevent and treat postpartum hemorrhage.• Bioavailability: Extensively absorbed from the GIT•Metabolism: De-esterified to prostaglandin F analogs• Half life: 20–40 minutes, with peak plasma levels at 10-15 minutes• Excretion: Mainly renal 80%, remainder is fecal: 15%

Oral misoprostol versus vaginal misoprostol (WHO)• Oral and vaginal misoprostol were similar with regard to all but one

of the priority outcomes: compared with vaginal misoprostol, oral misoprostol was associated with a lower risk of Apgar score being less than seven at 5 minutes of life

Oral or vaginal misoprostol versus sublingual/buccal misoprostol (WHO)• Trials indicate that vaginal and sublingual/buccal misoprostol are

similar with regard to all the priority outcomes. Data on oral versus sublingual/buccal misoprostol are limited and no firm conclusions can be drawn from them

(WHO)• Recommendations 1. Oral misoprostol (25 µg, 2-hourly) is recommended for induction of labour.

(moderate-quality evidence. strong recommendation.) 2. Vaginal low-dose misoprostol (25 µg, 6-hourly) is recommended for

induction of labour. (moderate-quality evidence. Weak recommendation.) 3. Misoprostol is not recommended for women with previous caesarean

section. (low-quality evidence. strong recommendation.)

• ADVANTAGES:• It is cheap, stable at room temperature• Long shelf life• Easily administered (oral, vaginal or rectal)• Less side effects• Induction delivery interval is short• Need for oxytocin augmentation is less• Failure of induction is less

• RISKS:• Uterine tachysystole (incidence 31-49%) with or without FHR changes are more common • Hyperstimulation (8%)• Rupture of uterus, rare• Meconium staining of liquor

MIFEPRISTONE• It is a 19-norsteroid with potent competitive antiprogestational & significant

antiglucocorticoid as well as antiandrogenic activity• It is available as 200mg tablet

PHARMACOKINETICS:• Active orally• Bioavailability 25%• Metabolised in liver• t1/2 - 20-36 hours

• MECHANISM OF ACTION:As it has greater affinity for progesterone receptor, it blocks the action of

progesterone at the cellular level.Fall in level of progesterone is considered as important event in the onset of

spontaneous labour.

• DOSAGE:• 200 mg orally• It decreases induction delivery interval• There is reduced need for prostaglandins

Nitric Oxide Donors • Cervical NO metabolite concentrations are increased at the beginning of uterine

contractions.• Cervical NO production is very low in postterm pregnancy • NO donors - isosorbide mononitrate and GTN1. Induces cervical COX-22. Brings about cervical ultrastructure rearrangement similar to that seen with

spontaneous cervical ripening.Despite this, clinical trials have not shown NO donors to be as effective as PGE2 for cervical ripening. Addition of isosorbide mononitrate to either dinoprostone or misoprostol did not enhance cervical ripening either in early or term pregnancy nor did it shorten time to vaginal delivery.Metaanalysis-do not appear to be useful for cervical ripening during labor induction.

ESTROGEN• Parturition studies in sheep showed that there is a prelabor rise in estrogen

associated with a decrease in progesterone - stimulate prostaglandin production - initiate labor. • Through this mechanism, estrogen has been suggested and studied as a cervical

ripening agent and labor induction agent. • This approach has limited widespread clinical applicability, because there is no

discussion of rates of vaginal delivery achieved within 24 hours or cervical status change after 12 to 24 hours. • Of note, the investigators reported that when comparing estrogen with placebo,

there were no differences in the rate of cesarean deliveries or in uterine hyperstimulation between groups. • Not currently used in common practice as an induction agent• Insufficient evidence to draw any conclusions regarding its efficacy.

RELAXIN• Protein hormone thought to have a promoting effect on cervical ripening through

connective tissue remodeling. • Source - corpus luteum of pregnancy.• Advantage – less risk of uterine hyperstimulation. • Most research on induction of labor with relaxin has used porcine or bovine

preparations and demonstrated improved efficacy over a placebo for cervical ripening.• With the advent of DNA technology, human recombinant relaxin has become

available for evaluation. Two studies totaling 113 women who received human recombinant relaxin for induction of labor compared with placebo showed no effect on cervical ripening or labor induction.

• The place of relaxin as an induction or cervical priming agent is unclear, and further trials are needed to determine its effect and place in current clinical practice.147

HYALURONIC ACID• The cervix is a fibrous organ composed principally of hyaluronic

acid, collagen, and proteoglycan. • Hyaluronic acid increases as pregnancy progresses, peaks after the

onset of labor, and decreases rapidly after birth of the infant.• The increase in the level of hyaluronic acid is associated with an

increase in tissue water content of the cervix, which is one of the mechanisms involved in cervical ripening. • In the past, investigators postulated that cervical injection of

hyaluronic acid would lead to cervical ripening. No data are available to assess its use for cervical ripening or labor induction.

METHODS THAT ARE NOT RECOMMENDED•Herbal supplements•Acupuncture•Homeopathy•Castor oil hot baths and enemas•Breast stimulation

AVAILABLE EVIDENCE DOES NOT SUPPORT ITS USE IOL

MECHANICAL METHODS

• They were among the first methods used for labor induction.• Advantages1. Less costly2. Less hyperstimulation3. Easy to store4. Result in fewer side effects for mother and fetus

• Disadvantages 1. Risk of infection2. Disruption of a low-lying placenta3. Some maternal discomfort on manipulation of the cervix.

MEMBRANES STRIPPING• Digital separation of the chorioamniotic

membrane from the wall of the cervix and lower uterine segment. • First reported in 1810 by Hamilton in England.• For membrane stripping, the fetal vertex

should be well applied to the cervix, and the cervix should be dilated sufficiently to allow introduction of the examiner’s finger.

• This process of membrane stripping is presumed to cause the release of endogenous prostaglandins from the adjacent membranes and decidua, as well as from the cervix (FERGUSON REFLEX).

•Many investigations have been conducted using routine membrane stripping at 38 or 39 weeks to either prevent prolonged pregnancies or decrease the frequency of more formal inductions occurring after 41 weeks.

•A metaanalysis including 19 trials demonstrated that routine membrane stripping at term will

1. Reduce the interval to spontaneous labor by 3 days2. Decrease the frequency of pregnancies continuing beyond

41 and 42 weeks 3. Lower the frequency of formal induction.

• There was no difference in the maternal or neonatal infection rate, or the rates of membrane rupture or cesarean delivery. • Complications 1. Rupture of membranes2. Hemorrhage from disruption of an occult placenta previa3. Development of chorioamnionitis.

There does not appear to be a contraindication to membrane stripping in Group B streptococcus (GBS)–colonized women. In accordance with Centers for Disease Control and Prevention guidelines, antibiotic prophylaxis should be administered to any GBScolonized woman once labor ensues or membrane rupture occurs.

WHO• Recommendation 1. Sweeping membranes is recommended for reducing formal induction of labour. (moderate quality evidence. strong recommendation.)• Remarks 1. The panel acknowledged that maternal discomfort and bleeding associated

with the procedure should be balanced with the anticipated benefits. since the interval between intervention and result (i.e. sweeping membranes and initiation of labour) can be longer than with formal methods of induction of labour, this intervention would be suitable for non-urgent indications for pregnancy termination.

2. Regarding breast stimulation, sexual intercourse and other similar methods of preinduction of labour, the participants in the technical consultation agreed that there was insufficient evidence for recommending those methods.

AMNIOTOMY ( Artificial Rupture of Membranes)• Technique involving the perforation of the chorioamniotic membranes.• It is used as a method of induction, either following prostaglandin with an

unfavourable cervix or as an initial procedure in women with favourable cervical scores• MECHANISM OF ONSET OF LABOUR:1. Streching of cervix2. Separation of membranes (liberation of prostaglandins)3. Reduction of amniotic fluid volume

• EFFECTIVENESS DEPENDS ON:• State of cervix• Station of presenting part• ADVANTAGES:• High success rate• Chance to observe the amniotic fluid for blood or meconium• Access to use fetal scalp electrode or intrauterine pressure catheter

or fetal scalp blood sampling• LIMITATIONS:• It cannot be employed in an unfavourable cervix (long, firm cervix

with os closed). The cervix should be atleast one finger dilated

• INDICATIONS:• Abruptio placenta• Chronic hydramnios• Severe preeclampsia-eclampsia• In combination with medical induction • To place scalp electrode for electronic fetal monitoring

• CONTRAINDICATIONS:• Intrauterine fetal death• Maternal AIDS• Genital active herpes infection

• IMMEDIATE BENEFICIAL EFFECTS OF ARM:• Relief of maternal distress in hydramnios• Control of bleeding in APH• Relief of tension in abruptio placenta & initiation of labour

• HAZARDS OF ARM:• Chance of cord prolapse• Amnionitis • Accidental injury to placenta, cervix, uterus, fetal parts or vasa previa• Liquor amnii embolism

PROCEDURE• Indoor procedure• Patient in lithotomy position after emptying her bladder• Two fingers are introduced into the vagina smeared with antiseptic ointment.

The index finger is passed through the cervical canal beyond the internal os. The membranes are swept free from the lower segment as far as reached by the finger• With one or two fingers still in the cervical canal with palmar surface

upward,a long Kocher’s forceps with blades closed or an amnion hook is introduced along the palmar aspect of fingers upto the membranes• The blades opened to seize the membranes and are torn by twisting

movements. Aminohook is used to scratch over the membranes

• This is followed by escape of amniotic fluid• Head not engaged-assistant should push the head to fix it to brim to prevent

cord prolapse• Head deeply engaged-gentle pushing of head up,facilitates escape of desired

amount of amniotic fluid• After the membranes rupture, following are to be assessed• 1) Colour of amniotic fluid• 2)Status of cervix• 3)Station of head• 4)Detection of cord prolapse• 5)Quality of FHR

TRANSCERVICAL BALLOON CATHETARS•A deflated Foley catheter, usually a 16 French(gabbe) 26

F(Williams) 30 mL balloon, can be passed through an undilated cervix into the extra-amniotic space and then inflated. The balloon is then retracted to rest against the internal os. • To add more traction, pressure may be applied by attaching a

weight such as a liter of intravenous fluid to the end of the catheter and suspending it with the force of gravity or by taping the catheter under tension to the patient’s inner thigh. The benefit of traction has not been proven, and may confer no added clinical benefit.

• No increased risk of preterm delivery in subsequent pregnancies following the placement of balloon catheters in the lower uterine segment.

• The Atad Ripener Device in place with the two balloons inflated.The uterine balloon is at the internal os and the cervicovaginal balloonis at the external os.

• EXTRA-AMNIOTIC SALINE INFUSION• Infusion of isotonic fluid into the extraovular space has been employed as an

adjunct to transcervical balloon catheter placement in the lower uterine segment. • The hypothesis – FERGUSON REFLEX • Most commonly, isotonic saline is used; hence, the name extra-amniotic saline

infusion (EASI) and is infused continuously at rates of 20 to 40 ml/h. • Cochrane review comparing EASI to any prostaglandin for cervical ripening

showed that EASI infusion was significantly less likely to result in vaginal delivery within 24 hours, had a higher risk of cesarean delivery and did not reduce the risk of hyperstimulation.• From these data, there is little support for the use of EASI as an adjunct to

transcervical balloon catheter placement.

WHO• Recommendations 1. Balloon catheter is recommended for induction of labour. (moderate-quality

evidence. strong recommendation.)2. The combination of balloon catheter plus oxytocin is recommended as an

alternative method when prostaglandins (including misoprostol) are not available or are contraindicated. (low-quality evidence. Weak recommendation.)

• Remark 1. The participants in the technical consultation noted that when using the balloon catheter for induction of labour it is important to monitor the woman and her fetus closely once labour is established. They also noted that balloon catheter and vaginal prostaglandins may have similar effectiveness. However, balloon catheter may be preferred for women with scarred uterus, since it is less likely to be associated with hyperstimulation of the uterus.

Hygroscopic dilators• They absorb endocervical and local tissue fluids,

causing the device to expand within the endocervix and provide mechanical pressure. • These dilators are either natural osmotic dilators

(e.g., Laminaria japonicum) or synthetic osmotic dilators (e.g., Lamicel- magnesium sulfate in polyvinyl alcohol), Dilapan (polyacrilonitrile)• Advantages: 1- Outpatient placement 2- No need for fetal monitoring3- Easy placement & removal4- Low cost

Risks :• Maternal & fetal infection• Bleeding • Membrane rupture• Placental separation

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