Induction of labour -- basics

1. INDUCTION OF LABOUR
POOJA SANALKUMAR

2. 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.
AUGMENTATION OF LABOUR:
The stimulation of spontaneous
contractions that are considered
inadequate for successful delivery.

3. INDICATIONS
1. PREGNANCY COMPLICATIONS
• Pregnancy induced hypertension
• Premature rupture of membranes
• Rh-incompatibility
• Diabetes
• Post maturity
• Antepartum hemorrhage
2. FETAL
• Fetal malformations
• Intrauterine death of fetus
3. MATERNAL
• Deteriorating maternal illness
• Elective induction

4. PREGNANCY INDUCED HYPERTENSION
•Gestational hypertension/PIH: hypertension that develops for the first time in pregnancy
after 20 weeks of gestation, no proteinuria & BP returns to normal within 12 weeks
postpartum.
•Preeclampsia: characterized by rise in blood pressure accompanied by proteinuria, edema
+/-
•Delivery within 48hrs is indicated in severe grades of preeclampsia not responding to
treatment to prevent maternal & fetal mortality rate.

5. PREMATURE RUPTURE OF MEMBRANES
•Spontaneous rupture of membranes occur during course of labour(first stage).
•PROM- membranes rupture before the onset of labour.

6. Rh-INCOMPATIBILITY
•Titre of agglutinin in maternal blood should be checked periodically in Rh-
negative mother.
•Isoimmunised pregnancies, antibodies cause hemolysis of fetal red cells.
•Labour is induced to shorten the exposure of infant to maternal antibodies.

7. DIABETES
Uncontrolled gestational diabetes mellitus or diabetes, induction is attempted
at 36 weeks to prevent sudden intrauterine death of the fetus.

8. POSTMATURITY
Indicated in all pregnancies that continue beyond 41 weeks to prevent fetal
compromise.

9. ANTEPARTUM HEMORRHAGE
Induction of labour is considered in premature separation
of placenta with a stable hemodynamic status.

10. FETAL MALFORMATIONS
Nonviable malformation (hydrocephalus,
anencephaly, achondroplasia) are
diagnosed antepartum, women is given an
option to terminate pregnancy by inducing
labour.

11. INTRAUTERINE FETAL DEATH
Mostly, spontaneous expulsion of fetus occurs in 3-5 weeks of Intrauterine
death.
Retention for longer periods may lead to coagulation failure.

12. DETERIORATING MATERNAL ILLNESS
•Hypertension
•Renal disease
•Liver disease
•Certain autoimmune disorders & malignancies

13. ELECTIVE INDUCTION
Induction of labour at full term in completely normal persons.
Not recommended, because of its association with increasing cesarean rate.

14. ABSOLUTE CONTRAINDICATIONS
Previous classical cesarean delivery or inverted
T-incision
Vasa previa or complete placenta previa
Active genital herpes infection
Non-reassuring fetal heart rate pattern
Contracted pelvis
Carcinoma cervix

15. RISKS
•Increased rates of cesarean delivery
•Increased maternal infectious morbidity
•Increased incidence of uterine rupture & hysterectomy

16. PREINDUCTION ASSESSMENT
• Gestational age and fetal size
• Determining presentation
• Performing a vaginal examination & assessing cervical status(Modified Bishop scoring
system)
• Reviewing patient’s pregnancy & medical history.
• Confirming fetal maturity
o36 weeks after positive serum/urine hcg pregnancy test result.
oUltrasound measurements at <20 weeks of gestation support a clinically estimated
gestational age of 39 weeks or more.
oFetal heart tones documented as present for 30 weeks by Doppler USG

17. METHODS OF INDUCTION
1. Unfavorable cervix
2. Favorable cervix

18. 1. UNFAVORABLE CERVIX
oHigh chance of unsuccessful induction.
Pharmacological techniques:
Prostaglandin E2
 Available as 0.5mg single use syringe.
 Repeated in 6hrs, upto a maximum of 3 doses.
Progesterone receptor antagonist (mifepristone)
Mechanical techniques:
Balloon catheter (transcervical Foley’s catheter-previous cesarean section)
Hygroscopic cervical dilators (laminaria tent, membrane sweeping)

19. 2. FAVORABLE CERVIX
Oxytocin drip: to simulate uterine activity cervical dilation & fetal descent without
causing uterine hyperstimulation or fetal distress.
◦ Dose: Oxytocin dilutes in 500ml of RL or NS. Low rate Infusion of 1-4mU/ml
◦ Initial dose: rate of 8 drops/min & increased every 30mins by 8 drops till
regular uterine contractions are achieved.
◦ Ideal dose: dose at which there is 3-4 contractions every 10mins each lasting
for 45 secs.

20. ◦ Discontinued if:
◦ Uterine contractions >5 in 10mins. Or 7 in 15mins.
◦ Uterine contractions lasts longer than 60 secs.
◦ Nonreassuring fetal heart rate pattern.
◦ Risks: uterine hyperstimulation, uterine rupture and water intoxication(20mU/min
or more fluids-may lead to convulsions, coma & death).

21. Methods of induction in favorable cervix contin.
Surgical incision amniotomy/Artificial rupture of membranes: stimulates uterine
activity by uterine decompression and prostaglandin release.
◦ Latent period before start of labour.
◦ Oxytocin infusion – if labour fails to start in 2 to 4 hrs.
◦ Main risks: Cord prolapse & infections

23. BISHOP SCORE
Cervical status
Score
0 1 2 3
Dilation(cm) closed 1-2 3-4 5+
Effacement(%) 0-30 40-50 60-70 >80
Consistency firm medium Soft
Position posterior middle anterior
Station of head -3 -2 -1, 0 +1, +2