This document defines induction of labor as artificially initiating uterine contractions before spontaneous labor begins. It lists several medical indications for induction, such as post-term pregnancy, preeclampsia, IUGR, and others. It also discusses contraindications and complications of induction. Several methods of induction are described, including pharmacological methods using prostaglandins and oxytocin, as well as non-pharmacological methods like membrane stripping, amniotomy, and balloon catheters. Factors that increase the success of induction like bishop score and gestational age are also summarized.

3. Defi--- Initiation of ut contraction before the onset
of spontaneous labor, with or without membranes.
after period of viability for purpose of vaginal
delivery.
It is indicated when there is risk of continuation
of preg either to mother or fetus.

4.  Indication ---
 Post maturity,
 PIH/ Eclampsia,
 Maternal medical complication ( Diabetes,
Chronic renal disease),
 Abruptio placenta,
 IUGR, PROM,
 IUD,
 Rh- iso immunisation,
 Fetus with major congenital anomaly,
 Oligohydramnios, Polyhydramnios

5.  CI --- CPD,
 Malpresentation,
 Previous classical caesarean section or
Hysterotomy,
 Unexplained vag bleeding, Placenta
praevia, Vasapraevia,
 Active genital herpes infection,
 High risk preg with fetal compromise,
 Heart disease,
 Pelvic tumour,
 Elderly primi with obstetric or medical
complication.

6.  Complication of induction ---
 Maternal--- Psychological upset, Tendency
to prolong labour due to abnormal ut
contraction, Increased operative
interference, Increased morbidity.
 Fetal --- Iatrogenic prematurity, Hypoxia
due to disordered ut contraction, prolonged
labour & operative interference.

7.  Following parameters are assessed
before induction ---
 Indication reassessed,
 Ensure fetal gestational age & maturity,
 Exclude CI for IOL,
 Assess Bishop Score ( >= 6 favorable),
 Ensure fetal well being.

8.  Factors for successful induction ----
 1 ) Period of gestation --- Preg near term /
post term
 2) Pre induction score – Bishop score >= 6
( Dilatation more important)
 3) Sensitivity of ut --- +ve oxytocin challenge
test
 4) Favorable in parous woman & in case of
PROM , Less responsive in elderly primi /
case with prolonged retention of dead fetus

9.  BISHOP SCORE
Parameter
s
Scores
0 1 2 3
Cx
Dilatation
Closed 1-2 3-4 5+
Cervical
length
3 2 1 0
Consistenc
y
Firm Medium Soft -
Position Posterio
r
Midline Anterior -
Head
station
-3 -2 -1,0 +1,+2

10. Total score = 13 , Favorable score = 6-13,
Unfavorable score = 0-5
Cervical ripening – It is series of complex
biochemical changes in Cx mediated by
hormones. Dilatation of collagen &
ground substance . Cx becomes soft &
pliable which is necessary for successful
normal deli. For favorable Cx cervical
ripening is must.

11.  Methods used for induction of labour ---
 Medical, surgical , Combined.
 Pharmacological ( medical ) method ---
Prostaglandins --- Dinoprostone(PGE2),
Misoprostol(PGE1), Dinoprost(PGF2alfa),
Prostaglandins ---Act locally on Cx. PGE2 &
PEF2alfa also causes myometrial
contraction.
 Oxytocin,
Steroid receptor antagonist (
Mifepristone[RU486], Onapristone), Relaxin

12.  PGE2 -- Has more collagenolytic property &
also sensitizes myometrium to oxytocin.
Intracervical PGE2 0.5mg gel is used for Cx
ripening , may be repeated 6hrly maximum
3/4doses. Woman should be in bed for
30min after application, monitor for ut
activity & FHR.

13.  PGE2 -- Is costly & needs refrigeration.
More effective when bishop score is less
& also sensitizes myometrium to
oxytocin.
 Complications-- May causes nausea,
vomiting , diarrhea. Hyperstimulation if
occurs may last longer & requires inj
terbutaline 0.2mg s.c.

14.  Misoprostol (PGE1) --- Used transvaginally
/ orally. 25 microgm transvaginally every
3hrs to maximum of 4 doses, orally
50microgm 4hrly. Used for cervical
ripening & induction.
 Advantage --- Is cheap, Stable at room temp,
Long shelf life, Easy to administer, Less side
effect, Induction delivery interval is short,
Failure of induction is less, Need of oxytocin
for augmentation is less.

15.  Disadvantage --- Hyperstimulation, Fetal
distress, Rupture of Ut, Lose motion,
Vomiting.
 CI --- Previous caesarian section, Asthma

16.  Oxytocin --- It is endogenous uterotonic .
Oxytocin receptors are more in fundus than
in Cx, receptor concentration increases as
preg advances & in labour. It acts by
receptor mediation, voltage mediated
calcium channels & prostaglandin
production . It is cheaper. It has short half
life(3-4min), plasma level falls rapidly when
IV infusion is stopped.

17.  It is to be kept in refrigerator. Effectiveness is
less with less bishop score, IUD, Lesser wks
of gestation. Uterine hyper stimulation is less
if controlled infusion is done, if occurs stops
following stoppages of infusion.
 Side effect--- Water intoxication due to ADH -
-effect in high doses.

18. Non pharmacological method (Surgical
induction) --- Stripping of membranes,
Amniotomy (ARM), Mechanical dilators,
Osmotic dilators(laminaria tents),
Balloon catheter.
Mechanism of onset of labour---
Stretching of Cx , Separation of
membrane ( release of prostaglandins),
Reduction of amniotic fluid vol.
 Effectiveness depends upon state of Cx,
Station of presenting part.

19.  ARM--- Advantages --- High success rate,
Can observe amniotic fluid for blood &
meconium, Access to use fetal scalp
electrode or intrauterine pressure catheter
or fetal scalp blood sampling.
Can not be used in unfavorable Cx
 CI – Maternal AIDS, Genital active herpes
infection, Chronic hydramnios as there is
risk of sudden massive drainage of liquor
leading to sudden uterine decompression &
may precipitate early placental separation
(abruption), in such controlled ARM is
done

20.  Immediate beneficial effect of ARM ---
Lowering of BP in PIH & Eclampsia, Relief of
maternal distress in hydramnios, Control of
bleeding in APH, Relief of tension in abruptio
placentae & initiation of labour.
 Hazards of ARM --- Once ARM is done one
has to deliver the Pt, Chance of umbilical cord
prolapse if head is not fixed. Amnionitis,
Accidental injury to vagina, Cx, Uterus, Fetal
part, Excessive bleeding in vasa- praevia.
Amniotic fluid embolism. Uncontrolled
escape of amniotic fluid & placental abruption

21.  ARM is a indoor procedure conducted in
labour room. Pt empties bladder.
Lithotomy position is given. With all
aseptic precaution 2 fingers are passed in
vagina & index finger passed beyond
internal os of Cx, stripping of membrane
is done [ not necessary if Cx is dilated >
3cm] , keeping 2 fingers in cervical canal
membrane is punctured with kocher’s
forceps / amnion hook.

22.  After rupture of membrane Colour of
amniotic fluid, Status of Cx, Station of
head, Detection of cord if present, FHR is
monitored
 SVP is kept & if necessary prophylactic
antibiotic is started.

23. Stripping of membrane --- It is digital
separation of chorioamniotic membrane
from the wall of Cx & lower uterine
segment. It causes release of endogenous
prostaglandins from membrane &
decidua. Manual exploration of Cx
triggers Ferguson reflex [ rise in maternal
plasma oxytocin level] by promoting
oxytocin release from maternal pituitary.
It is simple, safe & beneficial for induction
of labour, it is also used to make Cx ripe.

24.  Mechanical dilator --- Act by release of
endogenous prostaglandins from membrane
& maternal decidua to induce labour &
cervical ripening. Hygroscopic dilators e.g.
Laminaria tent ( seaweed) ,
Lamicel (MgSO4 in polyvinyl alcohol) acts
by absorption of water. They swell & forcibly
dilate Cx.

25. 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)

26.  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 pressure.
 It strips the fetal membranes from the lower uterine
segment, causing rupture of lysosomes , release of
phospholipase A and formation of prostaglandins.

27. 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.
The balloon is inflated with 30 to 50 ml of normal saline
and is retracted so that it rests on the internal os.
Constant pressure may be applied over the catheter.

28. 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.
Through this catheter extra amniotic 0.1%
ethacrydine lactate can be instilled.

30.  Combination method --- Medical &
surgical methods are used to increase
efficacy of induction by reducing
induction delivery interval.
 Advantage -- 1) More effective than
single procedure 2) Shortens induction
delivery interval thereby 3) Minimizes
risk of infection & lessens period of
observation
 Wherever possible, induction of labour
should be carried out in facilities where
cesarean section can be performed

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