Dr Ramya Pathiraja Senior Lecturer Faculty of Medical Sciences University of Sri Jayewrdenepura Sri Lanka

1. INDUCTION ANDINDUCTION AND
MECHANISM OFMECHANISM OF
LABOURLABOUR
Dr Ramya PathirajaDr Ramya Pathiraja
Senior LecturerSenior Lecturer
Faculty of Medical SciencesFaculty of Medical Sciences
University of Sri JayewardenepuraUniversity of Sri Jayewardenepura

2. objectivesobjectives
• Diagnosis of labour
• Stages of labour
• Management of labour
• Interpretation of CTG
• Induction of labour
• Oxytocic drugs

3. • Establishing the diagnosis of labour is the
most basic and essential aspect of labour
ward management
• Diagnosis of labour is based upon the onset of
regular contractions, which are of increasing
frequency and duration often associated with
blood stained mucous show and less often
rupture of membranes

4. • 10-15% neither woman nor the
attendant can confirm whether or not
they are in labour
• They should be reviewed over the next
2-6 hrs with repeat assessment of
cervix

5. • Uterine contractions are recorded by
frequency, duration and strength
• State of the cervix is recorded in
terms of its position, effacement and
dilatation

7. First stage of labourFirst stage of labour
• Onset of regular painful uterine
contractions to effacement and full
dilatation of the cervix
• There are three main components in the
assessment and management of the 1st
stage of labour
progress of labour
condition of the mother
condition of the fetus

8. • Main function of uterine contractions in
the first stage of labour is cervical
effacement and dilatation and to a
lesser degree, descent of the
presenting part
• Majority of the descent occurs in the
second stage of labour

9. • Position of fetal head may be
occipito anterior
occipito posterior
occipito transverse
• OP and OT positions are associated with
varying degrees of deflexion which presents a
larger diameter of the fetal head to the bony
pelvis

10. • Asynclitism
When one parietal bone presents at a
higher plane than the other when the
head in the transverse position
as it enter the pelvis
Anterior asynclitism is physiological and
posterior asynclitism indicate
disproportion

11. • Caput
Subjective assessment of oedema in the
scalp soft tissues
+ mild
++ moderate
+++ severe

12. • Moulding
none bones normally separated
+ bones touching
++ bones overlapping but easily separated
with digital pressure
+++ bones overlapping and not separable
with digital pressure

13. • Station of the presenting part
Level of the lowest part of the fetal bony
skull in relation to the ischial spines
With varying degrees of caput and moulding
position may be difficult to asses
combined vaginal and abdominal assessment
will be helpful

15. • If an incorrect diagnosis of labour is
made when the woman is in spurious
labour, a series of inappropriate
interventions ( amniotomy, oxytocin
augmentation, operative delivery) may
ensure over and demoralising period

16. Charting the progress of labourCharting the progress of labour
• Progress of labour
frequency and duration of uterine
contractions
cervical effacement and dilatation
descent of the presenting part
• Maternal conditions
BP, pulse ,temperature, and drugs
administered

17. • fetal conditions
Colour and quantity of amniotic fluid
Fetal heart rate

18. partogrampartogram
• Pictorial documentation of labour
• Assures systematic and logical approach
• facilitate early recognition of poor
progress

20. Rate of cervical dilatation has two phases
• A slow latent phase
during which cervix shortens from 3cm in
length to less than 0.5cm (effacement) and
dilates to 4 cm
• A faster active phase
Cervix dilates from 4 cm to full dilatation

21. • Alert line
In order to identify those are at risk of
prolonged labour, a line of acceptable
progress is drawn
• Action line
Is drawn 4hrs to the right of the alert
line

22. • Interventions thought to be necessary
if the rate of progress cut the action
line
• Latent phase of labour last upto 8 hrs in
nulliparous and 6hrs in multiparous
• In the active phase both nulliparous and
multiparous women dilates at a rate of
1cm/hr with multi often dilates more
rapidly

23. Upon admission to the labour roomUpon admission to the labour room
• Review antenatal record
• Physical examination-GE, BP, abdomen, FHS
• Urinalysis
• VE- confirm the diagnosis of labour
• If she is in labour, convey that to the
patient and if not send her back to the ward
after an assuring CTG

24. During the 1During the 1stst
stagestage
• Woman should be up and walking,
encouraged to assume most comfortable
position
• No woman in labour should be left alone
• Explanation of progress and any
interventions should be carefully
outlined to the woman and her partner

25. • Although there is enormous pressure on
nursing and medical staff to chart all
events for audit and medico legal
purpose, a balance between this and the
common sense, clinical care and
communication must be achieved

26. Pain relief in labourPain relief in labour
• Contnued support and explanation,
shortens labour, lessens the
requirement for analgesia and reduces
operative delivery
• Systemic narcotic analgesics
pethidine 50-150mg IM
IV pethidine and fentanyl

27. • As patient-controlled administration
• Inhalation analgesia-simple, safe, within
limits and effective
Entonox 50%N2O 50%O2
• Epidural analgesia

28. MCQMCQ
1. The active management of labour
includes
a. Induction of labour
b. Acceleration of labour
c. Use of a partogram
d. A high caesarean section rate
e. Continuous intrapartum fetal heart
monitoring

29. 2. A partogram
a. is a Pictorial documentation of labour
b. Increase the incidence of operative deliver
rate
c. Assures systematic and logical approach
d. facilitate early recognition of poor progress
e. will increase the work load of the labour
staff

30. summarysummary
• Diagnosis
• Terms – engagement, position,
caput,moulding
• Partogram
• Pain relief
• First stage

31. Non-progressive labourNon-progressive labour
• Powers
• Passages
• Passenger
often non progression is caused by
combination of all three

33. • Augmentation of labour
Amniotomy
Oxytocin infusion
Ineffective uterine contraction
Relative disproportion

34. • Non progressive labour is a trying event
for all concerned.
• Care during labour should be directed
towards sustaining the morale of the
women and her partner
• maintaining maternal hydration and
providing adequate analgesia

35. Second stage of labourSecond stage of labour
• Full dilation of the cervix to delivery of the
infant
• second stage has two phases
passive phase (pelvic phase)
Active phase (perineal phase)

36. passive phase (pelvic phase)
full dilatation of cervix to descend of the head
to the pelvic floor
• Multiparous – passive phase is very brief 30 mts
• Nulliparous- more time is required for
descend. 60 mts
•

37. • Active phase (perineal phase)
bearing down effort of the mother
begins

38. • Effect of epidural
spontaneous labour, endogenous production of
oxytocin increased which augment uterine
contractions causing descend of the
presenting part
physiological increase is blocked by epidural
due to interruption of Ferguson’s reflex
With epidural, augmentation with oxytocin is
necessary

39. • Epidural blunts maternal bearing down reflex
Epidural with selective sensory block and
augmentation with oxytocin will reduce
prolonged second stage and incidence of
assisted delivery

40. Length of second stage is influenced byLength of second stage is influenced by
• Parity
• Fetal weight
• Malposition (deflexed, OP, OT)
• Maternal effort
• Uerine contractions
• Epidural

41. • Assessment of progress of labour
Combined vaginal and abdominal examination
• Maternal position during labour
Woman’s own choice
Worst position is supine
Upright position- more comfortable and logical
Change position during labour
Many will choose semi-recumbent position

42. Maternal bearing downMaternal bearing down
• When to start ?
Nulliparous - full dilatation occurs when
head at mid pelvis
Unproductive, demoralizing, exhausting
• How ?
Valsalva maneuver
• Bad effects ?
FHR abnormalities
Low cord PH
Low Apgar score

43. Fetal surveillance in labourFetal surveillance in labour
4th
confidential inquiry into stillbirths
and deaths in infancy (CISD)
highlighted the need for good fetal
surveillance in labour
• Suboptimal interpretation of
intrapartum CTG
• inappropriate action
• poor communication
were highlighted

44. • Cerebral palsy attribute to 25%-30% of
intrapartum events in term pregnancies

45. Fetal heart rate monitoringFetal heart rate monitoring
Intermittent auscultation or continuous
fetal heart rate monitoring (CTG) ?
• Intermittent auscultation for 1 mt
through uterine contraction every 15 mts
during 1st
stage of labour and
after every other contraction OR
every 5 mts in the 2nd
stage of labour

46. Cont CTG is used
• If auscultation shows changes in
baseline rate, decelerations, irregular
heart rate
• difficulty in listening
• all high risk labours

47. Indications for cont CTGIndications for cont CTG
Intrapartum
• Oxytocin augmentation
• Epidural
• Vaginal bleeding in labour
• Maternal pyrexia
• Fresh meconium

48. CTG - Basic considerationsCTG - Basic considerations
• Baseline heart rate
Calculated by drawing a line through the
variability of the trace where there are no
acclerations or decelerations
110 – 160 bpm

49. baseline variabilitybaseline variability
• represents the integrity of the ANS
bandwith of the up and down excursions or
“wiggliness” of the trace
5 – 25 bpm
Reduced < 5 bpm
Suspicious CTG reduced longer than 40mts
but less than 90 mts
Abnormal CTG Reduced longer than 90 mts

50. AcclerationsAcclerations
• A rise in the baseline rate by more than 15
beats lasting for more than 15 sec
• Associated with fetal movements or other
fetal stimulation by uterine contractions or
pelvic examination
• Functioning CNS are necessary for FM
• Acclerations and normal baseline variability
are hallmarks of normal fetal oxygenation

51. DecelerationsDecelerations
• Drop in the baseline rate of more than 15
beats for longer than 15 sec
• Decelerations last less than 30 sec and
immediately following an accleration are
normal reflex changes in FHR

52. • Two types
early decelerations
mirror the contractions
occur in late first and second
stage are vagally mediated
not due to hypoxia
late decelerations

53. Important points to considerImportant points to consider
• Accelerations and normal baseline variability
are hallmarks of fetal health
• Accelerations with reduced baseline
variability should be considered suspicious
• Period of decreased variability may represent
fetal sleep
• Hypoxic fetus may have normal baseline heart
rate with no accelerations and reduced
baseline variability

54. • Placental abruption, cord prolapse and scar rupture
can give rise to acute hypoxia should be identified
clinically
• Hypoxia and acidosis develop faster with abnormal
trace in patients with scanty thick meconium, IUGR,
intrauterine infection and those who are pre or post
term
• In pre term, hypoxia and acidosis can predispose to
hyaline membrane disease, RDS and may contribute to
IVH – early action in the presence of abnormal trace

55. • Injudicious use of oxytocin, epidural
anesthesia and difficult deliveries
worsen hypoxia
• During labour if decelerations are
absent asphyxia is unlikely
• Abnormal patterns may represent not
only hypoxia, but also effects of drugs,
fetal anomaly, infection, cerebral
haemorrhage

56. Patterns of fetal hypoxiaPatterns of fetal hypoxia
Hypoxia can gradually develop
due to repeated occlusion of the cord
(manifest by variable decelerations)
decreased perfusion of the retroplacental
intervillous space reducing the oxygen
exchange during contractions (manifest by
late decelerations )

57. • Hypoxia is unlikely to develop during
labour without FHR decelerations
• Decelerations in the absence of rise in
BHR or reduction n the baseline
variability indicate cord compression or
reduced uteroplacental perfusion

58. • With repeated frequent decelerations
one of the first sign that indicate fetal
hypoxia is the cessation of
accelerations
• Fetus responds to hypoxia by increasing
the HR to circulate more blood through
placenta in an effort to get more
oxygen

59. • Thus with increasing hypoxia, there is
an increase in baseline HR until it
reaches a plateau
STRESS TO DISTRESS INTERVAL
• With baseline tachycardia, there is a
gradual reduction in baseline variability

60. • Combination of stable tachycardia with
silent or flat baseline variability
indicate that fetal ANS is probably
hypoxaemic
DISTRESS PERIOD
No intervention within a reasonable
time fetus may born with hypoxia and
acidosis

61. • If the situation is ignored FHR decline
rapidly leading to terminal bradycarda
DISTRESS TO DEATH INTERVAL can
be quite short 20- 60 mts

63. Chronic hypoxiaChronic hypoxia
• Pre existing hypoxia before the onset
of labour
• Non reactive trace with reduce or
absent baseline variability together
with shallow decelerations of < 15 bpm
• Which may start with uterine
contractions but not recover until after
the contraction is over

64. • Combination of shallow decelerations
with absent baseline variability is the
most ominous
• They may have normal BHR or mild
tachycardia
• These fetuses can deteriorate and die
within a short time with the stress of
contractions
• Early delivery is indicated

65. Acute hypoxiaAcute hypoxia
• Placental abruption
• Uterine rupture and scar dehiscence
• Cord prolapse
• Epidural analgesia
• Uterine hyperstimulation
Hypoxia and acidosis are likely to occur
if bradycardia cont > 10 mts

66. • Immediate delivery in the presence of
obvious cause
• Repositioning the woman
• Stop oxytocin infusion
• Tocolysis - terbutaline 0.25 mg SC/IV in
5 ml saline over 5 mts

67. Third stage of labourThird stage of labour
• Birth of infant until delivery of placenta
• Usually lasts 5-10 mts rarely more than 30
mts
• Shortest of all three stages but carries most
potential risk for the mother
• Placental separation
• haemostasis

68. Signs of placental separationSigns of placental separation
• Rising of uterine fundus and change from
broad discoid shape to a more narrow globular
form
• Gush of blood from the vagina
• Cord lengthening of 8-15 cm- reliable sign

69. Management of third stage of labourManagement of third stage of labour
• Expectant management
Normal physiological changes to bring about
placental seperation
Not effective
• Active management
Oxytocic drug with anterior shoulder induce
early and consistent uterine contractions
PPH, blood loss and need for blood transfusion
are all reduced by 40-50%

71. Factors influence risk of inductionFactors influence risk of induction
• Fetal maturity
• Parity
• State of the cervix
• Additional factors - CS

72. Modified Bishop ScoreModified Bishop Score
Pelvic
score
0 1 2 3
Position of
cervix
posterior middle anterior
Length of
cervix cm
>4 3 1-2 <1
Dilatation of
cervix cm
0 1-2 3-4 >4
Consistancy
of cervix
Firm medium soft
Station of
oresenting
part
-3 -2 -1/0 +1/+2

74. MCQMCQ
• The active management of labour
includes
a. Induction of labour
b. Augmentation of labour
c. Use of partogram
d. A high LSCS rate
e. Continuous intrapartum fetal heart
rate monitoring

75. • Ergometrine
A is given in dose of 250-500 micro grams
B is combined with oxytocin in syntometrine
C should not be given to hypertensive
patients
D act within 60 sec if given IV
E causes vomiting