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CONTENTS
1. Definition of normal Labour
2. Factors influencing progress of Labour
3. Diagnosis of Labour
4. Stages of Labour
5. Management of Labour
LABOUR DEFINITION
Labour is defined
The onset of regular painful uterine contractions with progressive
effacement and dilation of the cervix accompanied by decent of the
presenting part leading to expulsion of the fetus or fetuses and placenta
from the mother
Normal Labour is defined
to expel the viable(alive) products of conception
DIAGNOSIS OF LABOUR
Signs that can clue into the onset of Labour
• Show- evidence by mucus mixed with blood or mucus plug
• Rupture of membranes- look for leaking liquor
• painful, regular uterine contractions, at least (1:10)
VAGINAL EXAMINATION
Confirm degree of dilatation and effacement
Identify the presenting part
Fetal head engagement
Confirm or artificially rupture if necessary (ROM)
Exclude cord prolapse
FACTORS TO HELP DETERMINE IF LABOUR
IS NORMAL
Mature Fetus 37-42 weeks
Spontaneous expulsion
Vertex is the presenting part
Vaginal Delivery
Time ( not < 3hour but not >18 hours)
Complications??
INFLUENTIAL FACTORS OF THE PROGRESS
OF LABOUR
5P’s
• THE PASSENGER-Fetal head size, Fetal lie, presentation, attitude, position
• THE PASSAGE WAY/PELVIS
• THE POWERS
• THE PLACENTA
• PSYCHOLOGICAL RESPONSE
PHYSIOLOGY OF NORMAL LABOUR
POWERS
Physiology of normal labour complete into two steps
UTERINE CONTRACTION RETRACTION
1. Uterine contraction : During contraction, uterus becomes hard and somewhat pushed anteriorly to make the long axis of the uterus in the line with that of pelvic axis
2. Uterine contraction : Probable cause of pain are
a) Myometrial hypoxia during contractions.
b) Stretching of the peritoneum over the fundus.
c) Stretching of the cervix during dilatation.
d) Compression of the nerve ganglion.
e) The pain of uterine contractions is distributed along the cutaneous nerve distribution of T10 to L1
INTENSITY
The intensity gradually increases with advancement of
labour until it becomes maximum in the second stage during
delivery of the baby.
Intrauterine pressure is raised to 40-50 mm Hg during first
stage and about 100-120 mm Hg in the second stage of
labour during contractions.
In the first stage, the contractions last for about 30 second initially but
gradually increases in duration with the progress of labour.
Thus in the second stage, the contractions last longer than in the first stage.
FREQUENCY
In the early stage of labour, the contractions come at intervals of ten to fifteen
minutes. The intervals gradually shorten with advancement of labour until in the
second stage, when it comes every two or three minutes.
Retraction
Retraction is a phenomenon of the uterus in labour in which the muscle fibers are permanently shortened.
Unlike any other muscle of the body, the uterine muscles have this property to become shortened once and for all
Contraction
is a temporary reduction in length of the fibers, which attain their full length during relaxation. In contrast, retraction results in permanent shortening and the fibers are shortened once and for all.
The net effect of retraction on normal labour are:-
Essential property in the formation of lower uterine segment
Dilatation and effacement up of the cervix
To maintain the advancement of the presenting part made by the uterine contractions and to help in ultimate expulsion of the fetus.
To reduce the surface area of the uterus favouring separation of placenta.
Effective haemostasis after the separation of the placenta
The Passenger
The passage of the fetus through the birth canal is influenced by the
size of the fetal head and shoulder
the dimensions of the pelvic girdle
the fetal presentation and position
The bones of the cranial vault are not firmly united, and slight overlapping of the bones, or
moulding of the shape of the head, occurs during labour.
This capacity of the bones to slide over one another permits adaptation to the various
diameters of the pelvis.
Moulding can be extensive, but with most neonates the head assumes its normal shape
within about 3 days after birth.
MOULDING
The physiological gradual overlapping of the bones as the skull is
compressed during its passage in the birth canal.
One parietal bone overlaps the other and both overlap the
occipital and frontal bones so fontanelles are no more detectable.
It is of a good value in reducing the skull diameters but; severe
and / or rapid moulding is dangerous as it may cause intracranial
haemorrhage.
MOULDING
The bones of the fetal head
can move closer together or
overlap to help the head fit
through the pelvis.
Parietal bones overlap
occipital and frontal
from +0 to +3,
+0+1 being normal and +3
being cause for concern
The foetal head can move on the neck about 45 degrees in flexion or extension
Shoulders and Pelvic girdle Because of their mobility, the position of the shoulder (the
shoulder girdle) can be altered during labour, so that one shoulder may occupy a lower
level than the other. This permits a small shoulder diameter to negotiate the passage.
The circumference of the hips, or pelvic girdle, is usually small enough not to create
problems.
THE FETAL SKULL
diameters of the skull
Vertex Sub-occipito-bregmatic 9.5cm
OP Sub-occipito-frontal 10cm
Occipito-frontal 11.5 cm
Brow Mento-vertical 13.5cm
Face Sub-mento-bregmatic 9.5cm
DIAMETERS OF THE SKULL
Caput succedaneum is a diffuse swelling of the scalp
caused by the pressure of the scalp against the dilating
cervix during labour.
Caput can make it difficult to define the position of
the fetal head.
It is graded subjectively from 0 (none) to +3 (marked).
The bony pelvis
Pelvic
diame
ters
PELVIC PRIM /INLET
POST SACRAL PROMENTARY
ANTERIOR S.P
LATERALLY UPPER BORDER OF THE PUBIC BONE AND ILEO-PECTINEAL
LINE
TRANSVERSE DIAMETERE 13.5CM
AP DIAMETER 11CM
INLET ANGLE 60 DEGRESS
PELVIC MIDCAVITY
middle of the S.P
from the sides : pubic bone , inner aspect of the ischial bone
Posteriorly :S2-S3 Junction
almost round
AP Diameter 12 cm
Feel ischial spine vaginally station
Pelvic outlet
Anteriorly Lower margin of S.P
Laterally Pubic bone descending rami ,ischial tuberosity and
Sacro-tuberous ligament
Posteriorly end of sacrum
Ap diameter 13.5
Transverse diameter 11cm
FEMALE PELVIS
Basic framework for the
birth canal
True Pelvis- Inlet, cavity and
Outlet ( The fetus must pass
through all three in order
for labour to be sucessful)
Types of Pelvis- Gynaecoid,
Anthropoid, Android and
Platypelloid
CAUSES OF THE ONSET OF NORMAL LABOUR
It is unknown but the following theories are proposed:
1-Hormonal Factors
• Oestrogen Theory
• Progesterone withdrawal theory
• Prostaglandin Theory
• Oxytocin Theory
• Fetal Cortisol Theory
2- Mechanical Factors
• Uterine Distension Theory
• Stretch of the lower uterine segment
Hormonal factors:
(i) Oestrogen theory: During pregnancy, most of the oestrogens are present in a binding
form. During the last trimester, more free oestrogen appears increasing the excitability of
the myometrium and prostaglandins synthesis.
(ii) Progesterone withdrawal theory: Before labour, there is a drop in progesterone synthesis
leading to predominance of the excitatory action of oestrogens.
(iii) Prostaglandins theory: Postaglandins E2 and F2a are powerful stimulators of uterine
muscle activity
(iv) Oxytocin theory: Although oxytocin is a powerful stimulator of uterine contraction , its
natural role in onset of labour is doubtful. The secretion of oxytocinase enzyme from the
placenta is decreased near term due to placental ischaemia leading to predominance of
oxytocin’s action.
(v) Foetal cortisol theory: Increased cortisol production from the foetal adrenal gland
before labour may influence its onset by increasing oestrogen production from the placenta
Clinical Picture of Labour
Prodromal (pre - labour) stage:
Shelfing
Lightening
It is the relief of upper abdominal pressure symptoms as dyspnoea, dyspepsia and
palpitation due to Descent in the fundal level after engagement of the head
Pelvic pressure symptoms
With engagement of the presenting part the following symptoms may occur: -
Frequency of micturition. - Rectal tenesmus. - Difficulty in walking.
Increased vaginal discharge
False labour pain.
Onset of Labour:
True labour pain
The show
Dilatation of the cervix
STAGES OF LABOUR First Stage
Begins with the onset of true labour contractions and ends when the cervix is fully dilated (10cm).
Cervical effacement and dilatation occurs in this : Latent & Active
Latent: From diagnosis of labour to 3cm dilatation
Active: From 3cm to full dilatation (10cm)
It takes about 10-14 hours in primi gravida and about 6-8 hours in multi para.
The second stage of labour
begins with complete dilatation and ends with the birth of the baby. Approximately 2 hours in a nulliparous and 1 hour in a multi-para woman
Third stage
Begins after birth and ends with the expulsion of the placenta and membranes Shortest stage: After birth, up to 30 minutes
FIRST STAGE WHAT HAPPENS
1- Contractions
1. Regular
2. Increasing Frequency
3. Stronger
2- Cervical Dilatation and Effacement
3. Engagement of the presenting part
FIRST STAGE WHAT HAPPENS
Latent phase:
This is the first 3-4 cm of cervical dilatation
slow takes about 8 hours in nullipara and 4 hours in multipara.
The latent phase begins with mild, irregular uterine contractions that soften
and shorten the cervix
Active phase
Begin after 4 cm of cervical dilatation.
The normal rate of cervical dilatation in active phase is 1-1.2 cm/ hour in
primigravidae and 1.5 cm/hour in multiparae.
If the rate is < 1cm / hour it is considered prolonged
Quantitatives Assessment
Palpation
External tocodynamometry
Internal uterine pressure catheters.
95 % of women in labor will have 3-5 contractions per 10 minutes.
SECOND STAGE
First sign of the second stage is the urge to push
Full Dilatation to Delivery of the fetus
The median duration varies in nulliparous and multiparous women is 60 and 30 minutes, respectively.
Other factors may affect its duration:
Epidural analgesia
duration of the first stage
parity
maternal size
birth weight
station at complete dilation.
Signs to look for:-
Distention of the perineum
Satisfactory progress:- steady descent of the fetus through the birth canal & onset of the expulsive phase
(ACOG) has suggested that a prolonged second stage of labor should be
considered when the second stage of labour exceeds 3 hours in nulliparous and 2
hours in multiparous
MECHANISM OF LABOUR
Delivery of the head:
(1) Descent: It is continuous throughout labour particularly during the second
stage and caused by:
a. Uterine contractions and retractions.
b. The auxiliary forces brought by contraction of the diaphragm and abdominal
muscles.
c. The unfolding of the foetus
(2) Engagement:
The head normally engages in the oblique or transverse diameter of the inlet.
Flexion
Increased flexion of the head occurs when it meets the pelvic floor according to the
lever theory.
Increased flexion results in :
a. The suboccipito - bregmatic diameter (9.5cm) passes through the birth canal
instead of the suboccipito- frontal diameter (10 cm).
Internal rotation
The rule is that the part of foetus meets the pelvic floor first will rotate anteriorly. As
the head descends, the presenting part, usually in the transverse position, is rotated
about 45° to anteroposterior (AP) position under the symphysis
Extension
The suboccipital region lies under the symphysis then by head extension the vertex,
forehead and face come out successively.
Restitution:
After delivery, the head rotates 1/8 of a circle in the opposite direction of
internal rotation to undo the twist produced by it.
External rotation
The shoulders enter the pelvis in the opposite oblique diameter to that
previously passed by the head. When the anterior shoulder meets the pelvic floor
it rotates anteriorly 1/8 of a circle. This movement is transmitted to the head so
it rotates 1/8 of a circle in the same direction of restitution
PARTOGRAM partogram is a composite graphical
record of key data (maternal & fetal)
during labour entered against time on
a single sheet of paper.
COMPONENTS OF A PARTOGRAM
Patient Identification
Time (recorded in 1hr intervals)
Fetal Heart Rate
State of Membranes
Cervical Dilatation
Uterine Contractions
Drugs & Fluids
BP (2hr intervals)
Pulse Rate (30min intervals)
Oxytocin
Urinalysis
Temperature
THIRD STAGE
Begins with fetus delivery and ends with delivery of placenta/membranes
Two phases: Separation and Expulsion
30 mins or less
Average blood loss 150-250 mld
Birth of the placenta (Two stages)
• Separation of the placenta from the wall of the uterus and into the
lower uterine segment or vagina
• Actual expulsion of the placenta out of the birth canal
BIRTH OF THE PLACENTA Two methods:
Passive Management (wait for spontaneous expulsion of the
placenta)
Active Management
Active management of 3rd stage ,helps to prevent PPH
Includes:-
Use of oxytocin (given around the time of the anterior shoulder delivery, 10
units)
Controlled cord traction
Uterine massage
SIGNS OF SEPARATION
Globular and hard uterus
Sudden gush of blood
Cord Lengthening (Most reliable clinical sign)
EXAMINATION OF THE PERINEUM
look for lacerations
vulva outlet
vaginal canal & cervix should be inspected
Repair lacerations or episiotomies immediately or completeness and anomalies
IMMEDIATE CARE OF THE NEWBORN
Assess baby
Health baby with spontaneous respiration place on mother’s abdomen
APGAR scores
Engagement: The fetus is engaged if the widest leading part (typically the
widest circumference of the head) is entering the inlet
Station: Relationship of the bony presenting part of the fetus to the maternal
ischial spines.If at the level of the spines it is at “0 (zero)” station, if it
passed it by 2cm it is at “+2” station.
Attitude: Relationship of fetal head to spine: flexed, neutral (“military”), or
extended attitudes are possible.
Position: Relationship of presenting part to maternal pelvis, i.e. ROP=right
occiput posterior, or LOA=left occiput anterior.
Presentation: Relationship between the leading fetal part and the pelvic
inlet: cephalic, breech (complete, incomplete, frank or footling), face, brow,
mentum or shoulder presentation.
Lie: Relationship between the longitudinal axis of fetus and long axis of the
uterus: longitudinal, oblique, and transverse.
Pelvic types Traditional obstetrics characterizes four types of pelvises:
Gynecoid: Ideal shape, with round to slightly oval (obstetrical inlet slightly
less transverse) inlet: best chances for normal vaginal delivery.
Android: triangular inlet, and prominent ischial spines, more angulated pubic
arch.
Anthropoid: the widest transverse diameter is less than the anteroposterior
(obstetrical) diameter.
Platypelloid: Flat inlet with shortened obstetrical diameter.