Concise discussion on cervical ripening and induction of labour

1. Induction of Labour
By
Dr. A. A. Abudu

2. Outline
• Introduction
• Indications
• Contraindications
• Pre-induction assessment
• Cervical ripening
• Methods of induction
• Monitoring of induction process
• Complications
• Conclusion

3. Introduction
• Labour is defined as the onset of painful,
palpable and regular uterine contractions
which cause progressive cervical
effacement and dilatation and descent of
the foetal presenting part, leading to
expulsion of the foetus and placenta.
• Induction of labour is the artificial
initiation of this process, with the aim of
achieving vaginal delivery.

4. Introduction
• Rates of induction vary between countries
and facilities, ranging from as low as 1.4%
to 35.5% of all deliveries.
• Reasons for labour induction vary, but it
typically becomes necessary when the
maternal and/or foetal benefits of delivery
outweigh the potential risks of continuing
the pregnancy.

5. Indications
• Maternal:
• Preeclampsia and other hypertensive
diseases
• Deteriorating maternal disease
• Diabetes mellitus
• Renal, cardiac disease
• Sickle cell disease
• Cholestasis of pregnancy
• Autoimmune disease e.g. SLE

6. Indications
• Foetal:
• Prolonged pregnancy
• Rhesus incompatibility
• Foetal congenital abnormality
• Premature rupture of membranes
• Abruptio placenta
• Suspected IUGR
• Chorioamnionitis
• Foetal demise

7. Contraindications
• Maternal:
• Contracted pelvis
• Pelvic tumour
• Scarred uterus: classical CS, hysterotomy,
metroplasty, 2 previous CS
• Active genital herpes
• Cervical carcinoma
• Previous VVF repair
• Medical: advanced cardiac disease

8. Contraindications
• Foetoplacental:
• Placenta praevia, vasa praevia
• Malpresentation
• Foetal distress
• Suspected foetal macrosomia
• Cord prolapse
• Caution: grandmultiparity, previous LSCS,
multiple gestation

9. Pre-induction assessment
• Justifiable indication for induction
• Confirmed gestational age – inadvertent
prematurity
• Adequate counselling on indication,
benefit and risks
• Assessment to rule out existing
contraindications
• Foetal wellbeing assessment
• Baseline investigations

10. Pre-induction assessment
• Cervical status prior to onset of induction
• Modified Bishop Score
• Favourable score ≥6

11. Cervical ripening
• Ripening is the process by which the cervix
changes in consistency prior to the onset
of labour
• Reduction in collagen content, presence of
hyaluronic acid and increase in water
content = softening
• Methods include mechanical and
pharmacologic options.

12. Cervical ripening
• Mechanical options shown to have lower
complication rates of tachysystole, but
similar rates of caesarean delivery to
pharmacologic methods
• Mechanical methods include membrane
stripping, hygroscopic dilators and
transcervical balloon catheter, with or
without extraamniotic saline infusion
• Pharmacologic option involves the use of
prostaglandin derivatives

13. Cervical ripening - mechanical
• Membrane stripping
• A finger is inserted through the cervix
and rotated in a circular manner to
sweep (strip) the membranes from the
lower uterine segment
• It induces local prostaglandin formation,
thus enhancing ripening
• Risks: infection, membranes rupture,
bleeding

14. Cervical ripening - mechanical
• Hygroscopic dilators
• Placed in the endocervical canal
• Absorb endocervical tissue fluids,
causing the device to expand within the
endocervix and provide mechanical
pressure – dilatation, stimulate
prostaglandin release
• local effect only

15. Cervical ripening - mechanical
• Hygroscopic dilators:
• Can be natural osmotic dilators e.g.
laminaria tents (made from seaweed, L.
japonicum) or synthetic osmotic dilators
e.g. Lamicel, Dilapan
• Risk of infection

16. Cervical ripening - mechanical
• Transcervical balloon catheter :
• Introduced via the cervix into the
potential space between the membranes
and lower uterine segment, not the
endocervical canal
• Stimulates endogenous prostaglandin
and exerts direct pressure on the cervical
os

17. Cervical ripening - mechanical
• Transcervical balloon catheter:
• Introduced using aseptic technique
• Balloon inflated with 30-50ml of saline,
and retracted t rest against the cervix
• Catheter usually strapped to maintain
pressure on the cervix
• Removed after a 12 hour period for
reassessment
• Risks: membrane rupture, infection

18. Cervical ripening - mechanical
• Transcervical balloon catheter:

19. Cervical ripening - mechanical
• Extra-amniotic saline infusion:
• Infusion of normal saline into the extra-
amniotic space after passage of a
transcervical catheter
• Similar mechanism of action
• Found to be associated with lower rates
of infection complication, compared with
the catheter-only method

20. Cervical ripening - mechanical
• Extra-amniotic saline infusion:

21. Cervical ripening - pharmacologic
• Prostaglandins:
• Increase collagenase activity and
hyaluronic acid levels, thus promoting
rearrangement of extracellular matrix,
increased water content = ripening
• Increase in intracellular calcium ions =
increased myometrial contractility
• Risks: hyperstimulation, nausea and
vomiting, pyrexia, infection

22. • Prostaglandin E2 analogue – dinoprostone
• Prepidil, single use 0.5mg intracervical
gel. Repeated 6 hourly up to 3
doses/24hr or ripening achieved.
• Cervidil, 10mg slow-release vaginal
insert. Used for up to 12 hours or
ripening achieved.
• Delay in oxytocin use to avoid potentiated
effect
Cervical ripening - pharmacologic

23. Cervical ripening - pharmacologic

24. • Prostaglandin E1 analogue – misoprostol
• Off-label use, readily available, stored at
room temperature
• Oral and vaginal administration
• Dose: 25mcg 4-6 hourly, 6 doses/24hr
• Evidence shows more rapid cervical
ripening time and less need for oxytocin
compared with other methods
Cervical ripening - pharmacologic

25. • Nitric oxide donors:
• Nitric oxide thought to be a possible
mediator of cervical ripening
• Agents to stimulate local NO production
– isosorbide mononitrate and glyceryl
trinitrate
• Clinical trials have not shown them to be
as effective as prostaglandins
Cervical ripening - pharmacologic

26. • Mifepristone
• A progesterone receptor antagonist
• Counteracts the inhibitory effect of
progesterone on myometrium
• Maternal and foetal safety profile not
well documented
• Used in the UK in combination with
misoprostol for ripening and induction
following foetal demise
Cervical ripening - pharmacologic

28. Methods of Induction
• Can be medical, surgical or a combination
of both
• Methods used for cervical ripening may in
some cases result in actual onset of labour,
without need for further intervention: a
more common occurrence with use of
prostaglandins

29. Methods of Induction
• Prostaglandin E1 – misoprostol
• Associated with lower incidence of CS
• Incremental doses associated with
shorter induction-delivery time, less
need for oxytocin, but higher occurrence
of tachysystole
• Oral route associated with less
tachysystole, but more need for oxytocin
than vaginal route

30. Methods of Induction
• Oxytocin:
• Endogenous octapeptide produced in
the paraventricular nuclei, has
uterotonic and antidiuretic effects
• Synthetic analogue used in induction of
labour
• Effective with favourable cervix
• Risks: hyperstimulation, water
intoxication

31. Methods of Induction
• Oxytocin:
• Given by intravenous infusion, use of
infusion pump
• Dose titration to achieve adequate
contractions
• Half-life of 3 – 5 minutes, plasma steady
state concentration within 40 minutes
• Relationship between gestational age
and oxytocin receptor concentration

32. Methods of Induction
• Oxytocin:
• Higher dose regimen
associated with
shorter delivery time,
fewer operative
deliveries, less
incidence of neonatal
sepsis and
chorioamnionitis and
more uterine
hyperstimulation

33. Methods of Induction
• Oxytocin:
• 5U in 500mls of saline = 5,000mU in 500mls
= 10mU/ml
• 1ml = 20drops (infusion giving set)
• 20drops = 10mU of oxytocin
• 10drops/min = 5mU/min
• Increment of 10drops = 5mU every 30 minutes

34. Methods of Induction
• Amniotomy:
• Artificial rupture of membranes
• Requires favourable cervix for efficacy
• Implies commitment to delivery
• Results in reduction of amniotic fluid
volume and shortening the myometrial
muscle bundles

35. Methods of Induction
• Amniotomy:
• More effective alone, or in combination
with oxytocin infusion, than oxytocin
alone
• Risks – cord prolapse, abruptio placenta,
infection, injury
• Caution: HIV/AIDS, genital herpes

36. Methods of Induction
• Amniotomy:
• Aseptic, blind technique
• Instrument: amnihook, Kocher’s forceps
• Foetal heart rate check
• Appropriate descent of presenting part,
no cord presentation
• Guided release of amniotic fluid

37. Methods of Induction
• Non-medical methods:
• Relaxation techniques and visualization
• Walking, warm baths
• Sex – prostaglandin content of semen
• Nipple stimulation - ?oxytocin release
• Castor oil – oral, enema
• Food – spicy food, pineapples, cumin tea
• Herbs – evening primrose oil, black
cohosh

38. Monitoring of induction process
• Periodic cervical assessment
• Electronic monitoring with
cardiotocography, where available
• Routine management in labour: analgesia,
companionship, hydration
• Availability of facilities for caesarean
section, blood transfusion

39. Complications
• Failed induction – inability to achieve vaginal delivery
with induction
• Iatrogenic prematurity
• Risk of operative delivery
• Chorioamnionitis
• Uterine hyperstimulation
• Intrapartum haemorrhage – uterine rupture, abruptio,
trauma
• Foetal distress
• Postpartum haemorrhage
• Amniotic fluid embolism
• Water intoxication

40. Complications
• Uterine tachysystole: occurrence of >5
contractions in a 10-minute period
• Uterine tachysystole is further qualified as
being with or without FHR changes
• Hypertonus: refers to excessive uterine
contractions lasting >120secs
• Hyperstimulation: refers to excessive
uterine contractions (tachysystole or
hypertonus) with foetal heart rate changes

41. Conclusion
• Induction of labour not to be undertaken
lightly
• Cervical ripening and induction often a
continuous process
• Appropriate selection of method of
induction in individual patents, in view of
the relative benefits and risks

42. Thank you
for
listening