2. INDUCTION OF LABOUR implies the artificial
initiation of uterine contractions in a quiescent uterus
by any method like medical, surgical, or combined
prior to their spontaneous onsent beyond the period of
fetal viability.
AUGMENTATION OF LABOUR is the process of
accelerating the process of labour by the use of
oxytocics or an amniotomy in a uterus that has already
started the process of labour.
3. Evaluation before induction of labour
MATERNAL FETAL
1. Confirm indication for
induction
2. Review contraindications to
labor and/or vaginal delivery
3. Perform clinical pelvimetry to
assess pelvic shape and
adequacy of bony pelvis
4. Assess cervical condition
(assign Bishop score)
5. Review risks, benefits and
alternatives of induction of
labor with patient
1. Confirm gestational age
2. Assess need to document fetal
lung maturity status
3. Estimate fetal weight (either by
clinical or ultrasound
examination)
4. Determine fetal presentation and
lie
5. Confirm fetal well-being
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
Chronic hypertension
Maternal medical condition
Systemic lupus erythematosus
Gestational diabetes
Hypercoagulable disorders
Cholestasis of pregnancy
Polyhydramnios
Fetal anomalies requiring
specialized neonatal care
Logistic factors
Risk of rapid labor
Distance from hospital
Psychosocial indications
Advanced cervical dilatation
Previous still birth
Post term pregnancy(>41weeks)
10. CONTRAINDICATIONS
ABSOLUTE
Previous uterine scar of
hysterotomy, classical cesarean
delivery or repair of uterine
rupture
Active genital herpes infection
Placenta or vasa previa
Umbilical cord prolapse
Transverse or oblique fetal lie
Contracted pelvis
RELATIVE
Cervical fibroid
Severe cardiac disease
Malpresentation (breech)
Non assuring fetal status (fetal
distress)
11. 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
12.
13. 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
15. 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.
17. 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
18. 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 .
19.
20. 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
21. Other Predictive factors for
successful Induction Of Labour
Period of gestation
Pre induction score
Sensitivity of the uterus
Presence of fetal fibronectin in vaginal swab >50ng/ml
Maternal height >5’
Normal BMI
Estimated fetal weight <3kg
22. 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.
23. ULTRASOUND IMAGING
Advantages over digital examination: more objective and
assesses the entire length of the cervix.
Both bishop’s score and TVUS predict successful induction.
Bishop’s score predicts delivery within 24 hrs. and TVUS
within 48 hrs.
In TVUS cervical length, internal cervical OS, shape and
assessment of angle between the cervical axis and the wall of
the inferior uterine segment are measured.
Studies have not found any USG parameter predictive, and
consider bishop’s score to be superior.
24. 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.
25. 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
26. 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.
27. ADVANTAGES DISADVANTAGES
Cheap
Outpatient placement
Easy for placement
No need for fetal monitoring
Rapid improvement of
cervical status
Skill needed for proper placement in
internal os.
Delay in obtaining maximum effect.
Patient discomfort.
Inability of tents to be molded
without compromising mechanical
integrity.
Lack of manufacturer specifications
for natural dilators.
Potential for incomplete sterility.
28. 5. Membrane stripping:
Release of endogenous PGs.
and mechanical dilation.
results in less labor inductions
less post dated pregnancies
more spontaneous onset of labor
- inexpensive, safe, efficacious in promoting labor
over several days
29. 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.
30. Single Balloon Devices
A fluid filled balloon is inserted inside the cervix.
A Foley catheter 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.
31. 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.
32. 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.
35. 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.
36. 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.
38. Cervical Ripening
Alter the extracellular ground substance
of the cervix
increases the activity of collagenase in
the cervix.
Increase in elastase, glycosaminoglycan, dermatan
sulfate, and hyaluronic acid levels in the cervix.
A relaxation of cervical smooth muscle facilitates
dilation.
Increase in intracellular calcium levels,
~ contraction of myometrial muscle
Prostaglandin E2: (Dinoprostone)
39. 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.
41. 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.
44. 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.
45. PGE2 can cause
Uterine hyperstimulation, Fetal distress and Cesarean section.
Uterine hyperstimulation :
Uterine hyperstimulation (defined as contraction frequency
being more than five in 10 minutes or contractions
exceeding 2 minutes in duration)
- More common with intra vaginal application.
- 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.
48. 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.
49. 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 is suggested.
50. Compared with higher doses of vaginal misoprostol, lower doses (25 μg, 6-
hourly) are associated with a reduced risk of uterine hyperstimulation
with fetal heart rate changes.
The risk of vaginal birth not being achieved within 24 hours is similar with
both higher and lower doses
51. Recommendations
1. Oral misoprostol (25 μg, 3-hourly) is recommended for induction of
labour.
(Moderate-quality evidence. Strong recommendation.)
2. Vaginal low-dose misoprostol (25 μg, 3-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.)
52. Side effects :
Tachysystole
Meconium passage
Uterine rupture
53. OXYTOCIN
It’s a nonapeptide synthesized in the supraoptic and
paraventricular nuclei of the hypothalamus.
Has a half life of 3–4 minutes and a duration of
action of approximately 20 minutes.
It is rapidly metabolized and degraded by
oxytocinase.
54. 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. Bound intracellular calcium is eventually
mobilized from the sarcoplasmic reticulum to activate
the contractile protein.The uterine contractions are
physiological i.e. causing fundal contraction with
relaxation of the cervix.
55. DANGERS OF OXYTOCIN
Uterine hyperstimulation (overactivity)
Uterine rupture
Water intoxication is due to its antidiuretic
function when used in high dose (30-40 mIU/min)
Hypotension
Antidiuresis
Fetal distress, fetal hypoxia or even fetal death
may occur due to uterine hyperstimulation.
56. For induction of labor
Principles:
(1) Because of safety, the oxytocin should be started
with a low dose and is escalated at an interval of 20-
30 minutes where there is no response. When the
optimal response is achieved (uterine contraction
sustained for about 45 seconds and numbering 3
contractions in 10 minutes), the administration of the
particular concentration in mU/per minute is to be
continued. This is called oxytocin titration technique.
(2) The objective of oxytocin administration is not
only to initiate effective uterine contractions but
also to maintain the normal pattern of uterine
activity till delivery and at least 30-60 minutes beyond
that.
57. Convenient regime:
Because of wide variation in response, it is a sound
practice to start with a low dose (1-2 mU/min) and
to escalate by 1-2 mIU/min at every 20 min
intervals up to 8 mU/min. The patient should
preferably lie on one side or in semi-Fowler’s position
to minimize venacaval compression.
58. AMNIOTOMY
Effectiveness depends on : (1) State of the cervix (2)
Station of the presenting part. Induction delivery
interval is shorter when amniotomy is combined with
oxytocin than when either method is used singly.
Advantages of amniotomy : (a) High success rate (b)
Chance to observe the amniotic fluid for blood or
meconium (c) Access to use fetal scalp electrode or
intrauterine pressure catheter or for fetal scalp blood
sampling.
Limitation: It cannot be employed in an unfavorable
cervix (long, firm cervix with os closed). The cervix
should be at least one finger dilated.
60. Immediate beneficial effects of ARM
• Lowering of the blood pressure in pre-eclampsia and
eclampsia.
• Relief of maternal distress in hydramnios.
• Control of bleeding in APH.
• Relief of tension in abruptio placentae and initiation of
labor.
61. HAZARDS OF ARM
Chance of umbilical cord prolapse
Amnionitis
Accidental injury to the placenta, cervix or uterus, fetal
parts or vasa-previa
Liquor amnii embolism (rare).
