Obstetrics

1. 1. Definition & Purpose
2. Indications
3. Contraindications
4. Methods of Induction of Labour (Medical)
KASTURI RAMASAMY

2. Definition of Labour
 Series of events that take place in the genital
organs in effort to expel viable products of
conception out of the womb through the
vagina into the outer world

3. Definition
 “Initiation of labour by artificial means prior
to its spontaneous onset at a viable
gestational age, with the aim of achieving
vaginal delivery in a pregnant woman with
intact membranes” (WHO)

4.  Augmentation: Stimulation of spontaneous
contractions [both in frequency and intensity] that are
considered inadequate for successful delivery.
 Elective induction: Initiation of labour at term pregnancy
without any acceptable medical or obstetric
indication

5. Purpose of Induction of Labour
When the risks of continuation of pregnancy
either to the mother or to the fetus is more,
induction is indicated.
Induction of labor is indicated when the benefits of
termination of pregnancy to the mother or
the fetus outweigh those of continuing the
pregnancy.

6. Indications for Induction of Labour
Pre-eclampsia, eclampsia
(hypertensive disorders in
pregnancy)
Maternal medical
complications [DM, Chronic
renal disease, Cholestasis
of pregnancy]
Post maturity
Abruptio placenta
[Antepartum hemorrhage
except p. previa]
Intrauterine Growth
Restriction (IUGR)
Rh-isoimmunisation
PROM
Fetus with major
congenital anomaly
Intrauterine death of the
fetus
Oligohydramnios and
polyhydramnios –chronic
Unstable lie after correction
into longitudinal lie

7. Contraindications of
Induction of Labour
Contracted pelvic
and cephalopelvic
disproportion.
Malpresentation
[breech, transverse
or oblique lie]
Previous classical
cesarean section or
hysterotomy
Uteroplacental
factors [Unexplained
vaginal bleeding,
vasaprevia, placenta
previa]
Active genital herpes
infection
High risk pregnancy
with fetal
compromise
Heart disease Pelvic tumor
Elderly primigravida
with obstetric or
medical
complications
Umbilical cord
prolapse
Cervical carcinoma

8. Dangers of Induction of Labour
FETAL
Psychological upset [Induction failure/C-
sect]
Tendency of prolonged labor due to
abnormal uterine action
Increase need for analgesia during labour
Increased operative interference
Increase morbidity
Iatrogenic prematurity
Hypoxia due to uterine
dysfunction
Prolonged labor
Operative interference
MATERNAL

9. Parameter to Assess Prior to Induction
of Labour
MATERNAL FETAL
To confirm the indication for IOL
Exclude the contraindication of IOL
Assess Bishop score
(score >6,favorable)
• Perform clinical pelvimetry to assess pelvic
adequacy.
• Adequate counseling about the risks, benefits and
the alternatives of IOL with the woman and the
family members.
To ensure fetal gestational age
To estimate fetal weight
Ensure fetal lung maturation status
Ensure fetal presentation and lie
Confirm fetal well being

10. Bishop’s Score
Total score
13
Favourable
6-13
Unfavourable
0-5

11. Modified Bishop’s Score
Total score
13
Favourable
6-13
Unfavourable
0-5

12. Factors for Successful Induction of
Labour
Period of
gestation
Nearer the term
or post-term –
success
Pre-induction
score
Bishop score ≥
6 is favourable
Dilatation of
cervix is most
important
Sensitivity of
the uterus
Positive
oxytocin
sensitivity test
Cervical
ripening
Favourable in
parous woman
& in cases with
PROM.
Less responsive
in elderly
primigravida or
cases with
prolonged
retention of
dead fetus
Presence of
fetal fibronectin
in vaginal swab
( >50ng/mL)
Favourable for
successful IOL

13. A series of complex biochemical changes in the cervix
which is mediated by the hormones –alteration of both
cervical collagen & ground substance  soft and pliable
cervix

14. Methods of Cervical Ripening
Pharmacological Methods Non-pharmacological method
Prostaglandins
• Dinoprostone (PGE2) –gel, tablet, suppository
• Misoprostol (PGE1) –tablet **
Oxytocin
Progesterone receptor antagonist
• Mifepristone
Relaxin
Hyaluronic Acid
Oestrogen
Stripping the membranes
Amniotomy (Artificial rupture of
membranes)
Mechanical dilators, osmotic
dilators (laminaria)
Transcervical balloon catheter

15. Medical
Intrauterine fetal
death
PROM
In combination with
surgical induction
(ARM)
Surgical
Abruptio placenta
Chronic hydramnios
Severe pre-eclampsia
or eclampsia
In combination with
medical induction
Combined
To shorten the
induction –delivery
interval (Commonly
done)

16. Medical Induction of Labour
1. Prostaglandins
Act locally (autocrine & paracrine hormones) on the
contiguous cells
Prostaglandins
PG E2
Cervical
ripening**
Myometrial
contraction
PG F2alpha
Myometrial
contraction

17. 1. Prostaglandin
Dinoprostone (PGE2)
Action
• Collagenolytic properties for cervical softening &
dilatation
• Myometrial contraction
• Sensitizes myometrium to oxytocin
Administration & Dose
• Vaginal Tab/ Vaginal gel, 0.5 mg,
• May be repeated after 6 hours for 3 or 4 doses if
required
Side effects
• Uterine tachysystole; >5 contractions in a 10-minute
period, qualified by presence/absence of fetal heart rate.

18. 1. Prostaglandin
Misoprostol (PGE1)
Action
 Cervical ripening
 Myometrial contraction
 Sensitizes myometrium to oxytocin
Administration & Dose
 Vaginal pessary, 25μg every 4 hours (total: 6-8 doses)
 Oral
Effectiveness
 Decreased the need for oxytocin induction
 Not approved for labour induction or abortion
 Contraindicated in women with previous caesarian birth
Side effects
 Uterine tachysystole
 Increased frequency of meconium-stained amniotic fluid

19. 2. Oxytocin
OXYTOCIN (uterotonic –stimulate uterine contractions)
MOA
 Receptor mediation: Binds to specific G-protein coupled receptors on
myometrium  increased production of PGs by endometrium 
contraction of pregnant uterus
 Voltage mediated calcium channels
 Prostaglandin production
Administration & Dose  IV infusion *
Effectiveness
 Non pregnant uterus is not responsive to oxytocin
 In early pregnancy, higher dose of oxytocin is required to stimulate uterus
 3rd trimester, responsiveness increases
 More effective when cervix is ripe
Side effects
 Uterine hyperstimulation
 Fetal hypoxia, fetal death
 Water intoxication (headache, nausea, vomiting, drowsiness, convulsion)

20. Oxytocin drip is discontinued if;
- uterine contractions >5 in 10 minutes or 7 in 15 minutes
- uterine contractions last longer than 60 to 90 seconds
- fetal heart rate pattern becomes non-reassuring
Oxytocin regimens for stimulation of labour
Regimen
Starting dose
(mU/min)
Incremental
increase
(mU/min)
Dosage interval
(min)
Maximum dose
(mU/min)
Low dose
0.5 – 1
1 – 2
1
2
30-40
15
20
40
High dose 6 6,3,1 15-40 42

21. 3. Mifepristone
MOA
 Competitive receptor antagonist of progesterone
 Blocks both progesterone and glucocorticoid receptors
 Luteolytic property
 Cervical ripening and induction of labour
Administration & Dose
 Single oral dose of 600 mg of mifepristone, followed by 48 hours
gemeprost (PGE1) 1 mg vaginal pessary OR
 200mg vaginally daily for 2 days
Side effects
 Nausea, vomiting
 Diarrhea
 Abdominal pain
 Headache
 Uterine bleeding
 Teratogenicity

22. OXYTOCIN PROSTAGLANDIN (PGE1, PGE2)
COST  Cheaper  Costly (PG E2 > PG E1)
STABILITY
 Needs refrigeration [1 month kept
at 30ºc ]
 PGE2 : refrigeration
 PGE1 : room temperature
ADMINISTRATION  IV infusion  Intravaginally/ orally
EFFECTIVENESS
 Less with :
 Low bishop score
 IUFD
 Lesser week of pregnancy
 More effective :
 More collagenolytic properties
 Sensitizes myometrium to oxytocin
SIDE EFFECTS
 Uterine hyperstimulation with high
dose –Ceases follow stopping of
infusion
 Tachystole last longer
[ Rx: Terbutaline 0.2mg sc.]
SYSTEMIC EFFECTS  Less ; water intoxication
 Troublesome with IV or oral
 Less with vaginal route
ADH EFFECTS  In high dose  Absent