2. Induction of labor – Implies stimulation of contractions
before the spontaneous onset of labor, with or without
membranes.
Augmentation refers to stimulation of spontaneous that
are considered to be inadequate because of failed cervical
dilatation and fetal descent
3. Evaluation before induction of labour
MATERNAL FETAL
1. Confirm indication for induction 1. Confirm gestational age
2. Review contraindications to labor 2. Assess need to document fetal
and/or vaginal delivery lung maturity status
3. Perform clinical pelvimetry to 3. Estimate fetal weight (either by
assess pelvic shape and adequacy clinical or ultrasound
of bony pelvis
examination)
4. Determine fetal presentation and
4. Assess cervical condition (assign
lie
Bishop score)
5. Confirm fetal well-being
5. Review risks, benefits and
alternatives of induction of labor
with patient
4. WHO RECOMMENDATIONS FOR INDUCTION OF
LABOUR
Induction of labour should be performed only when there is a clear
medical indication for it and the expected benefits outweigh its
potential harms.
In applying the recommendations, consideration must be given to
the actual condition, wishes and preferences of each woman, with
emphasis being placed on cervical status, the specific method of
induction of labour and associated conditions such as parity and
rupture of membranes.
5. Induction of labour should be performed with caution since the
procedure carries the risk of uterine hyperstimulation and
rupture and fetal distress.
Wherever induction of labour is carried out, facilities should be
available for assessing maternal and fetal well-being
6. Women receiving oxytocin, misoprostol or other prostaglandins
should never be left unattended
Failed induction of labour does not necessarily indicate
caesarean section
Wherever possible, induction of labour should be carried out in
facilities where cesarean section can be performed
9. RELATIVE INDICATIONS
Hypertensive disorders Fetal anomalies requiring
Chronic hypertension specialized neonatal care
Maternal medical condition
Logistic factors
Systemic lupus erythematosus
Risk of rapid labor
Gestational diabetes
Distance from hospital
Hypercoagulable disorders
Psychosocial indications
Cholestasis of pregnancy
Advanced cervical dilatation
Polyhydramnios
Previous still birth
Post term pregnancy(>41weeks)
10. CONTRAINDICATIONS
ABSOLUTE RELATIVE
Prior classic uterine incision or Cervical carcinoma
transfundal uterine surgery Funic presentation
Active genital herpes infection Malpresentation (breech)
Placenta or vasa previa
Umbilical cord prolapse
Transverse or oblique fetal lie
Absolute cephalopelvic
disproportion (as in women with
pelvic deformities)
11. RELATIVE INDICATIONS
Hypertensive disorders Fetal anomalies requiring
Chronic hypertension specialized neonatal care
Maternal medical condition
Logistic factors
Systemic lupus erythematosus
Risk of rapid labor
Gestational diabetes
Distance from hospital
Hypercoagulable disorders
Psychosocial indications
Cholestasis of pregnancy
Advanced cervical dilatation
Polyhydramnios
Previous still birth
Post term pregnancy(>41weeks)
12. CONTRAINDICATIONS
ABSOLUTE RELATIVE
Prior classic uterine incision or Cervical carcinoma
transfundal uterine surgery Funic presentation
Active genital herpes infection Malpresentation (breech)
Placenta or vasa previa
Umbilical cord prolapse
Transverse or oblique fetal lie
Absolute cephalopelvic
disproportion (as in women with
pelvic deformities)
13. Risks
CESAREAN DELIVERY
especially increased in nulliparas
two- to threefold risks
rates are inversely related with favorability of the cervix at induction,
that is, the Bishop score.
CHORIOAMNIONITIS
UTERINE ATONY
Postpartum atony and hemorrhage are more common in women
undergoing induction or augmentation
Intractable atony was the indication for a third of all cesarean
hysterectomies
15. Cervical ripening : A prelude to the onset of labour whereby the cervix
becomes soft and compliant.
This allows its shape to change from being long and closed, to being
thinned out (effaced) and starting to open (dilate).
It either occurs naturally or as a result of physical or pharmacological
interventions
NICE 2008
16. Smooth muscle
Cellular
Fibroblast
Collagen I (70%)
Cervix Collagen III
(30%)
Elastin
Extra cellular
Proteoglycans
Decorin
17. MECHANISM INVOLVED IN CERVICAL RIPENING
Cervix is a complex and heterogeneous organ, that undergoes
extensive changes throughout gestation and parturition.
Chronic process, which begins within the first trimester of pregnancy
and progressively proceeds until term
Softens, dilates and effaces the cervix
This remodeling process is extremely complex and involves
properly timed biochemical cascades,
interaction between cellular and extra cellular components, and
infiltration by inflammatory cells.
18. Hyperplasia of cellular components in early gestation
physiologic cell death, in advanced pregnancy
Up gradation of -Invasion by neutrophils
and macrophages
Decorin
-Nitric oxide – regulates
MMPs and releases PGs.
COLLAGEN REMODELLING
20. Extra-cellular changes
Dispersion and Disorganization of Collagen
Collagenases, Proteases and Elastases (produced by fibroblast and
PMN)
MMP 1 and 8 – source: stromal cells and neutrophils
Proteoglycans e.g. Decorin
Inflammatory cells--- increase in degradative enzymes
Hyaluronic acid (GAG)- increase water content
21. Remodeling of cervix
Degradative
Inhibitors
enzymes
-Collagenases, MMP 1 &
- Tissue inhibitors of
8, elastases
MMPs, alpha 2 macroglobulin
-Source – stromal cells,
neutrophils and
macrophages
-Activity enhanced by
cytokines like IL-1B, IL-8
22. AFFECTING ELEMENTS
CYTOKINES –
e.g. interleukin-1β enhance the activity of collagenases
and interleukin 8,
Platelet activating factor,
monocyte chemotactic factor-1
HORMONAL INFLUENCES –
Estrogens increases collagenases
Progesterones inhibit collagenases, hyaluronic acid & IL-8
NITRIC OXIDE stimulates leukocytes infiltration
induce prostaglandin secretion
23. PREINDUCTION CERVICAL RIPENING
The condition of the cervix influences the success of inducing labor.
A cervical examination is essential before labor induction is initiated.
In 1964, Bishop developed a scoring system to evaluate multiparous women
for elective induction at term.
The scoring system is based on properties of the cervix that may be assessed
clinically at the time of pelvic examination such as
dilatation, effacement, consistency, and position as well as the station of the
fetal presenting part
24. “Bishop Scoring System” Used for Assessment of Inducibility
DILATATION EFFACEMENT STATION CERVICAL CERVICAL
SCORE
POSITION
(cm) (%) (–3 to +2) CONSISTENCY
0 CLOSED 0 - 30 -3 FIRM POSTERIOR
1 1-2 40 - 50 -2 MEDIUM MID
POSITION
2 3-4 60 - 70 -1 SOFT ANTERIOR
3 >/= 5 >/=80 +1, +2 - -
25. Bishop score is now widely used to predict the success of
labor induction.
The higher the Bishop score, the more “ripe” or
“favorable” the cervix is for labor induction.
A low Bishop score, usually considered less than or equal
to 6, is “unripened” or “unfavorable” and will benefit from
cervical ripening
26. Other predictors
Maternal
factors
Height, Fetal
Parity Age Fetal factors
weight, BMI fibronectin Insulin like
growth
Factor
Fetal weight binding
>3.5kg. protein
Gestational
age
fFN in cervical
secretions:
Not more
predictive than
Bishop’s score
27. Other scoring systems
Field’s system
Burnett modification of bishops score
Weighted Bishop’s score by Friedman
Pelvic score by Lange
However, despite this none of the modifications have shown
improved predictability.
28. ULTRASOUND IMAGING
Adv. Over digital examination: more objective and assesses the entire length of
the cervix.
Both bishop’s score and TVUS predicted successful induction.
Bishop’s score predicted delivery within 24 hrs. and TVUS within 48 hrs.
Cervical length related to latent phase of labor, funneling related to both latent
and active phase of labor. (Am. J of Obs. Gynecol. 1994;171.)
Some other studies have not found any USG parameter predictive, and consider
bishop’s score to be superior.
29. METHODS OF CERVICAL RIPENING
Unfortunately, women too frequently have an indication for induction but
with an unfavorable cervix.
As favorability or Bishop score decreases, there is an increasingly
unsuccessful induction rate.
Methods used for cervical ripening include pharmacological preparations
and various forms of mechanical cervical distension.
30. Non pharmacologic means of cervical ripening
1. Herbal supplements: evening primrose oil, blue and black cohosh,
raspberry leaves.
2. Breast stimulation: causes oxytocin release.
Adv–non invasive, inexpensive, simple
Disadv. – causes FHR abnormalities.
3. Castor oil, hot baths, enemas
4. Miscellaneous - acupuncture , sexual intercourse
31. 4. (HYGROSCOPIC DILATORS):
Natural osmotic dilators –
Laminaria japonicum
Laminaria digitata
Isapgol
Synthetic osmotic dilators
Lamicel
Dilapan
They absorb endocervical and local tissue fluids, causing the device to
expand within the endocervix and provide mechanical pressure.
cause mechanical dilation and release of prostaglandins.
Swell up to 4 – 5 times.
Most rapidly in first 4-6 hours but continue to swell up to 24 hours later.
32. ADVANTAGES DISADVANTAGES
Skill needed for proper placement in
Cheap
internal os.
Outpatient placement
Delay in obtaining maximum effect.
Easy for placement
Patient discomfort.
No need for fetal monitoring
Inability of tents to be molded without
Rapid improvement of compromising mechanical integrity.
cervical status Lack of manufacturer specifications for
natural dilators.
Potential for incomplete sterility. ETO
gas does not eradicate spores in the
interstices of the sea weed stem
33. 5. Membrane stripping:
Release of endogenous PGs. and mechanical dilation.
results in < labor inductions
< post dated pregnancies
> spontaneous onset of labor
- inexpensive, safe, efficacious in promoting labor over several days
34. 6. Balloon devices :
Single / Double balloon
First described in 1967
Safe
Cheap
ADVANTAGES:
The combination of balloon catheter plus oxytocin is recommended as an
alternative method when prostaglandins (including misoprostol) are not
available or are contraindicated (previous caesarean)
May be useful for outpatient ripening.
Can be inserted in presence or absence of membranes.
Associated with favorable Bishop scores and no additional side effects.
35. Single Balloon Devices
A fluid filled balloon is inserted inside the cervix.
A Foley catheter (26 Fr) or specifically designed balloon devices can be
used
Mechanism of action:
The mechanism by which Foley' s catheter improves the cervical state is by
its mechanical action.
It strips the fetal membranes from the lower uterine segment, causing
rupture of lysosomes , release of phospholipase A and formation of
prostaglandins.
36. Technique of Balloon Placement
1. After sterilization and draping, the catheter is introduced into the endocervix
either by direct visualization or blindly by sliding it over fingers through the
endocervix into the potential space between the amniotic membrane & the
lower uterine segment.
2. The balloon is inflated with 30 to 50 mL of normal saline and is retracted so
that it rests on the internal os.
3. Constant pressure may be applied over the catheter. e.g. a bag filled with 1 L
of fluid may be attached to the catheter end / An intermittent pressure may
also be exerted on the catheter end 2 -4 times per hour.
37. 4. Catheter is removed at the time of rupture of membranes or may
be expelled spontaneously which indicate a cervical dilatation of
3 - 4 Centimeters.
40. PROSTAGLANDINS
The chemical precursor is arachidonic acid
PGs are endogenous compounds found in the
myometrium, deciduas, and fetal membranes during pregnancy.
Cervical production of PGE2, PGI2, PGF increases at term.
Modulate fibroblast activity - Increase hyaluronic acid production
Acting as chemotactic agents, Inflammatory cells further release
degradative enzymes, causing cervical ripening.
41. Prostaglandins administration results in dissolution of collagen bundles and
an increase in sub mucosal water content of the cervix.
These changes in cervical connective tissue at term are similar to
those observed in early labor.
Unlike oxytocin, response to prostaglandins does not change throughout
gestation.
43. Prostaglandin E2: (Dinoprostone)
Increase in elastase, glycosaminoglycan, dermatan
sulfate, and hyaluronic acid levels in the cervix.
A relaxation of cervical smooth muscle facilitates
dilation.
Alter the extracellular ground substance
of the cervix Increase in intracellular calcium levels,
increases the activity of collagenase in ~ contraction of myometrial muscle
the cervix.
Cervical Ripening
44. PROSTAGLANDIN E2 (DINOPROSTONE):
CERVIPRIME GEL - is commonly used for cervical ripening .
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 pre-filled syringe is placed intracervically,
and the gel is deposited just below the internal cervical os.
After application she remains reclined for at least 30 minutes. Doses may be
repeated every 6 hours, with a maximum of three doses recommended in 24
hours.
46. Dinoprostone should only be administered at hospital.
Continuous Uterine activity & FHR monitoring.
If optimal response is not achieved by 6 hours, another dose can be
administered. The maximum allowed dose is 3 doses be administered per
24 hours.
Oxytocin should not be initiated until 6 to12 hours after the last dose
because of the potential for uterine hyperstimulation with concurrent
oxytocin and prostaglandin administration.
49. Vaginal insert containing 10 mg of dinoprostone in a timed-release
formulation. The vaginal insert administers the medication at 0.3 mg/h
and may be left in place for up to 12 hours.
ADVANTAGE: the insert may be removed with the onset of active
labor, rupture of membranes, or with the development of uterine
hyperstimulation.
51. COCHRANE REVIEW
Vaginal Prostaglandin E2 versus placebo/no treatment
(37 trials, 6511 women)
vaginal No Rx / risk 95%
PGE2 Placebo ratio confidence
(RR) interval (CI)
risk of the cervix remaining unchanged/ 5 trials, 467 women 21.6% 40.3%, 0.46 0.35 to 0.62
unfavourable after
12 to 24 hours
reduction in failure to achieve vaginal delivery 2 trials, 384 women 18.1% 98.9%, 0.19 0.14 to 0.25
within 24 hours
use of oxytocin augmentation 12 trials, 1321 women 35.1% 43.8% 0.83 0.73 to 0.94
Uterine hyperstimulation with FHR changes 14 trials, 1259 women 4.4% 0.49%, 4.14 1.93 to 8.90
Hyperstimulation without FHR changes 13 trials, 3636 Women 1.4% 0.4% 2.48 1.17 to 5.26
52. COCHRANE REVIEW
Vehicle comparisons
PGE2 gel is as efficacious as PGE2 tablets.
PGE2 gel does reduce the need for oxytocin augmentation,
Gel was associated with less uterine hyperstimulation.
Sustained release pessaries in comparison with gel
have not been shown to significantly reduce caesarean section rates
have not been shown to improve adverse neonatal or maternal outcomes.
There is reduction in the use of oxytocin augmentation and the reduction in
instrumental delivery rates.
The frequency of vaginal examinations is reduced when using sustained
release pessaries.
53. INTRACERVICAL PGE2: although this route of administration is
effective, it offers no advantages when compared to other methods of
administration, namely the vaginal route.
Intracervical prostaglandins are effective compared to placebo, but
appear inferior when compared to intravaginal prostaglandins.
54. PGE2 can cause
Uterine hyperstimulation, Fetal distress and Cesarean section.
Uterine hyperstimulation :
- More common with intra vaginal application.
- 1-5%, similar to low dose oxytocin <=4mu/ml.
- Begins within 1 hr
- Removal, irrigation of Cervix, vagina : not helpful
- Rapidly reversed with terbutaline or removal of insert.
- Hence fetal heart rate monitoring is needed for 2 hours following single
dose and longer if contractions persist after that.
55. A retrospective study of case notes (n = 3099) investigated women who
underwent induction with PGE2 (vaginal tablet, gel and intracervical gel).
Uterine hyperstimulation (defined as contraction frequency being more
than five in 10 minutes or contractions exceeding 2 minutes in duration)
occurred in 5.8% patients, of which 31.5% were associated with FHR
abnormalities.
Administration of tocolytic treatment with β2-adrenergic drugs
(hexoprenaline at 0.3 micrograms/minute
OR
single dose of terbutaline 250 micrograms intravenously or
subcutaneously)
successful in normalising uterine contractions and reversing any FHR
abnormality in (98.3%).
Improvement usually began within 5 minutes regardless of
hyperstimulation patterns.
NICE 2008
57. Safety in induction for VBAC
Concern is with uterine rupture caused by uterotonic effects.
In largest cohort study of 5022 patients willing for VBAC
453 patients received intra vaginal gel
The rates of rupture were, 1.3% with PGE2 and 0.7 without its
use.
~ not statistically significant.
Am J of Perinatol. 1997;14:157-160
58. Two studies have expanded on the differences in adverse outcomes between
prostaglandin and non-prostaglandin (such as intracervical Foley catheter) based
induction regimens. In the NICHD study, prostaglandin induction compared with
non-prostaglandin induction incurred a non-significantly higher risk of uterine
rupture (140/10,000 versus 89/10,000; P = 0.22).
In an analysis of nationally collected data from Scotland, prostaglandin induction
compared with non-prostaglandin induction was associated with a statistically
significantly higher uterine rupture risk (87/10,000 versus 29/10,000) and a higher
risk of perinatal death from uterine rupture(11.2/10,000 versus 4.5/10,000).
This compares with 6/10,000 risk of perinatal death in women with an unscarred uterus
induced by prostaglandin identified by a Cochrane review.
RCOG
59. Given these risks and the absence of direct robust
evidence, it is important not to exceed the safe
recommended limit for prostaglandin priming in
women with prior caesarean birth.
RCOG 2007
60. Use with Premature Rupture of Membranes at term.
It has not been shown to decrease neonatal infections when compared with
expectant management.
It could decrease time to delivery, but this can be achieved equally with
optimum oxytocin dosing.
More important intervention to decrease maternal infectious morbidity is
decreasing number of PV examinations.
62. Pharmacokinetics
Route of administration: Oral, vaginal and sublingual route for induction.
Bioavailability: Extensively absorbed from the GIT
Metabolism: De-esterified to prostaglandin F analogs
Half life: 20–40 minutes
Excretion: Mainly renal 80%, remainder is fecal: 15%
maximum plasma conc. with 400µg miso.
- 34 mins. after oral , 80 mins. After vaginal
- rapid onset and greater peak action with oral miso.
- longer action with vaginal miso.
63. Clinical trials indicate that the safe optimal dose and dosing
interval is 25 mcg intravaginally every 4-6 hours.
ACOG 1999
A maximum of 6 doses was suggested.
64. VAGINAL MISOPROSTOL (comparison)
Vaginal misoprostol versus Trials/ No. of women Outcomes
Placebo/ Expectant 5 trials/ Reduced risk of not
management 769 participants achieving vaginal birth
within 24 hrs of induction
Intravenous oxytocin •9 trials/1200 participants •Reduced risk of not
achieving vaginal birth
•25trials/3074 participants •Fewer cesarean sections
•13 trials/1906 participants •Fewer infants with apgars
below 7 at 5mins
Other prostaglandins - •a reduced risk of vaginal birth not
achieved within 24 hours
•fewer caesarean sections
•increased risk of uterine
hyperstimulation with fetal heart rate
changes
65. Compared with higher doses of vaginal misoprostol, lower doses (25 μg, 6-
hourly) were associated with a reduced risk of uterine hyperstimulation
with fetal heart rate changes (16 trials, 2540 participants, RR 0.51, 95% CI
0.37–0.69).
The risk of vaginal birth not being achieved within 24 hours was similar
with both higher and lower doses
66. ORAL MISOPROSTOL
Oral misoprostol versus Trials/ No. of women Outcomes
Placebo/ Expectant •1 trials/96 participants •Reduced risk of not
achieving vaginal birth
management within 24 hrs of induction
•6 trials/629 participants
•Reduced cesarean births
Intravenous oxytocin •8 trials/1026 participants •Similar w. r, t. the risk of
priority outcomes
Intracervical prostaglandins •More effective in
achieving vaginal birth
within 24 hrs
Vaginal prostaglandins •Reduction in cesarean
rates
67. Lower doses of oral misoprostol (up to 50 μg) were
associated with similar outcomes compared with higher
doses (100 μg)
68. Oral misoprostol versus vaginal misoprostol
Similar with regard to priority outcomes except
Oral misoprostol was associated with a lower risk of Apgar score being
less than seven at 5 minutes of life (14 trials, 3270 participants, 94
events, RR 0.65, 95% CI 0.44–0.97).
69. Vaginal misoprostol versus sublingual/ buccal misoprostol :
similar with regard to all the priority outcomes
Oral versus sublingual/buccal misoprostol: Data are limited
70. 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.)
71. Misoprostol vs Dinoprostone
The mean time to vaginal delivery was significantly shorter in the
misoprostol group (925.8 versus 1577.6 minutes), and
the mean duration of the active length of labour was significantly shorter in
the misoprostol group (353.7 versus 496.8 minutes)
Less likely to require a repeated dose of prostaglandin for cervical priming and
oxytocin for augmentation of labour.
no difference in the rate of Caesarean section
More hyperstimulation during labour in the misoprostol group
Aust N Z J Obstet Gynaecol. 2001 May;41(2):145-52
72. Oxytocin for cervical ripening : comparison
Intravenous Oxytocin Trials / Outcome
versus No women
Expectant management 25 trials; Intravenous oxytocin reduced the failure to
6660 women achieve vaginal delivery within 24 hours
when compared with expectant management
(8.4% versus 54%)
Vaginal PGE2 27 trials; compared with vaginal PGE2, oxytocin was
4564 women associated with more failures to achieve
vaginal delivery within 24 hours
(70% versus 21%)
Intracervical PGE2 14 trials; Oxytocin was associated with increased
1331 women unsuccessful vaginal deliveries
within 24 hours when compared with
intracervical PGE2
(50.4% versus 34.6%)
Increase in cesarean sections (19% versus
13.7%)
73. CONCLUSION
Comparison of oxytocin with either intravaginal or intracervical PGE2 reveals
that the prostaglandin agents probably increase the chances of achieving
vaginal birth within 24 hours.
Oxytocin induction may increase the rate of interventions in labour.
NICE 2008
76. Risks
CESAREAN DELIVERY
especially increased in nulliparas
two- to threefold risks
rates are inversely related with favorability of the cervix at induction,
that is, the Bishop score.
CHORIOAMNIONITIS
UTERINE ATONY
Postpartum atony and hemorrhage are more common in women
undergoing induction or augmentation
Intractable atony was the indication for a third of all cesarean
hysterectomies