Normal labour and puerperium Flashcards
Define labour
Physiological process during which the fetus, membranes, umbilical cord and placenta are expelled from the uterus
What may initiate labour
- change in oestrogen/progesterone ratio
- fetal adrenals and pituitary hormones
- myometrial stretch increasing excitability
- mechanical stretch of cervix and stripping of fetal membranes
- fergusons reflex
What is the role of progesterone in influencing onset of labour?
Keeps the uterus settled
Prevents the formation of gap junctions
Hinders the ocntractibility of myocytes
What is the role of oestrogen in the onset of labour?
Makes the uterus contract
Promotes prostaglandin production
What is the role of oxytocin in the onset of labour?
Initiates and sustains contractions
Acts on decidual tissue to promote prostaglandin release
Where is oxytocin synthesised?
In decidual and extraembryonic fetal tissue in the placenta
What happens to the number of oxytocin receptors near the end of pregnancy?
Number of receptors increases in myometrial and decidual tissues near the end of pregnancy
What is the role of pulmonary surfactant secreted into amniotic fluid
Stimulates prostaglandin synthesis
What does increase in production of fetal cortisol stimulate?
An increase in maternal estriol
What does increase in myometrial oxytocin receptors cause?
Phosphatase C activity and subsequent increase in cytosolitic calcium and uterine contractility
What is the role of liquor?
Nurtures and protects fetus and facilitates movement
What is the timing of rupture of membranes?
- pre-term
- pre-labour
- first stage
- second stage
- born in a caul
What does cervical tissue consist of?
Collagen tissue mainly (types 1, 2, 3, 4) smooth muscle, elastin, held together by connective tissue ground substance
Describe the processes in cervical softening?
- increase in hyaluronic acid gives increase in molecules among collagen fibres
- decrease in bridging among collagen fibres gives decrease in firmness of cervix
What happens in cervical ripening?
- decrease in collagen fibre alignment
- decrease in collagen fibre strength
- decrease in tensile strength of the cervical matrix
- increase in cervical decorin (dermatan sulphate proteoglycan 2)
What is the bishops score?
- position
- consistency
- effacement
- dilatation
- station in pelvis
most simple way to determine if it is safe to induce labour
What are the stages of labour?
- first stage
- latent phase up to 3-4cms dilatation
- active stage 4cms-10cms (full dilatation)
- second stage
- full dilatation- delivery of baby
- third stage
- delivery of baby- expulsion of placenta and membranes
What happens in the latent phase of 1st stage of labour?
- mild irregular contractions
- cervix shortens and softens, duration variable
may last an uncomfortable few days…
What happens in the active phase of labour?
- 4cms -> full dilatation
- slow descent of the presenting part
- contractions progressively become more rhythmic and stronger
- normal progress is assessed at 1-2cms per hour
- analgesia, mobility and parity is increased variably
What is the second stage of labour?
Complete dilatation of the cervix (10cm) to delivery of the baby
When is the second stage of labour considered to be prolonged?
- in nulliparous women- if it exceeds 3 hours if there is regional anaesthesia, or 2 hours without
- in multiparous women, the second stage considered prolonged if it exceeds 2 hours with regional analgesia or 1 hour without
What is the third stage of labour?
Delivery of the baby to expulsion of the placenta and foetal membranes
Average duration 10 minutes but can be 3 minutes or longer
When is preparation made for removal of the placenta and fetal membranes under GA?
after 1 hour
Describe expectant and active management of the third stage of labour?
Expectant: spontaenous delivery of the placenta
Active management: use of oxytoxic drugs and controlled cord traction is preferred for lowering risk of post partum haemorrhage
What are braxton-hicks contractions?
Tightening of the uterine muscles, thought to be to aid the body prepare for birth
Can start 6 weeks into pregnancy but more usually felt in the third trimester
What is the character of braxton hicks contractions?
Irregular, do not increase in frequency or intensity
Resolve with ambulation or change in activity
Relatively painless
When do true labour contractions happen?
Under the influence of the release of oxytocin, which stimulates the uterus to contract
What is true labour?
When the timing of contractions become evenly spaced, and the time between them gets shorter and shorter.
Length of contraction lasts increases 10s-45s
WIll get more intense and painful over time
What are the three key factors in labour?
Power: uterine contraction
Passage: maternal pelvis
Passenger: Foetus
What contributes to the power of contractions?
Uterine muscle: Smooth muscle (myocyte) in connective tissue (collagen and elastin) density highest at the fundus
Pacemaker: region of the tubal ostia, wave spreads in a downward direction
Synchronisation of contractions waves from both ostia
Polarity: upper segment contracts and relaxes, lower segment and cervix stretch, dilate and relax
Normal contractions have a fundal dominance with a regular paterrern and an adequate resting tone
How often do contractions occur?
3-4 in 10 minutes
How long do contractions last?
Initially 10-15 seconds, slowly builds up
What are the types of pelvis?
Anhtropoid
Android
Gynaecoid
Platypelloid
Descreibe an anthropoid pelvis
Oval shaped inlet with large anterior-posterior diameter and comparatively smaller transverse diameter
Describe an android pelivs?
Has a triangular or heart-shaped inlet and is narrower from the front
African-caribbean women are more at risk of having an android shaped pelvis
What are the 5 evaluating parameters for the cervix?
- effacement
- dilatation
- firmness
- position
- level of presenting part or station
What is the normal foetal position?
Longitudinal lie
Cephalic presentation
Presenting part: vertex
In which position should the foetal head be?
Occiptoanterior; head engages in occipito-transverse
Flexed
What is an abnormal foetal position?
Breech, oblique, transverse lie
Occipitoposterior
What can be felt in vaginal examination to determine the position?
Fontanelles
What are the analgesia options for birth?
- paracetamol/co-codamol
- TENS
- entonox
- diamorphine
- epidural
- remifentanyl
- combined spinal/epidural
What is a partogram?
A graphic record of key data (both maternal and foetal) contained on one sheet, used to assess the progress of labour
Cervical dilatation, foetal heart rate
What are 7 cardinal movements?
- engagement
- descent
- flexion
- internal rotation
- crowning and extension
- restitution and external rotation (optimal position for shoulders)
- expulsion, anterior shoulder first
What is engagement?
- passage of the widest diameter of the presenting part to a level below the plane of the pelvic inlet
- the sagittal suture is frequently deflected either posteriorly to the promontory or anteriorly to the symphysis pubis, such lateral deflection is known as anterior and posterior asynclitism
What is descent?
Downward passage of the presenting part through the pelvis
When is the foetal head engaged?
When the widest diameter of the head has entered the brim of the pelvis. This is also described as 3 fifths of the foetal head having entered the pelvis and 2 fifths still being felt abdominally.
What do we need to observe during descent of the head?
- abdominal fifths- reference points
- maternal discomfort and feeling of pressure
- frontal synciput and occupital eminences
- vaginal examinations for cervical assessment
vaginal examinations should be carried out approximately _ hourly in normal labour
should not be carried out inappropriately just for information
4
Why does the foetal head change position as it descends?
As it engages it assumes an occiput transverse position because that is the widest pelvic diameter available for the widest part of the foetal head
Describe the cardinal movement of flexion
Flexion of the foetal head occurs passively as the head descends due to the shape of the bony pelvis and the resistance offered by soft tissues
Describe internal rotation of the head
Rotation of the presenting part from its original position (usually transverse with regard to the birth canal) to the anterior position as it passes through the pelvis
Describe extension
Occurs once the foetus has reached the level of the interoitus, bringing the base of occiput in contact the inferior margin at the symphysis pubis.
Describe external rotation (restitution)
is return of the foetal head to the correct anatomic position in relation to the foetal torso
Describe expulsion
Delivery of the rest of the foetal body
What is crowning?
Appearence of a large segment of foetal head at the interoitus
Labia are stretched to full capacity
Largest diameter of foetal head is encircled by the vulval ring
What does crowning feel like for mum?
Burning and stinging
How should delivery of the head be managed?
Slowly with hands guiding but not leading the exit at crowning to prevent rapid extension of the tissues and perineal tearing
Episiotomy may be required
What can immediate clamping of the umbilical cord cause?
Reduction in the red blood cells an infant recieves at birth by more than 50%, resulting in potential short-term and long-term neonatal problems
When should delayed cord clamping be carried out?
All the time, unless immediate resuscitation is necessary, this is from cessation of pulsations or up to 3 minutes after expulsion
Why is skin to skin important?
Helps keeps babies warm and calm and improve other aspects of babies life outwith the womb
How long should uninterupted SSC be after birth?
1 hour
When does expulsion of placenta normally occur?
5-10 minutes after delivery, considered normal up to 30 minutes
What are the 3 classic signs indicating separation?
Uterus contracts, hardens and rises
Umbilical cord lengthens permanently
Frequently a gush of blood in variable amounts
Placenta and membranes appear at introitus
What is the active management of 3rd stage?
- prophylactic administration of syntometerine.. 1ml ampule containing 500micrograms ergometrine maleate and 5IU oxytocin
OR
- oxytocin 10 units
- Cord clamping and cutting, controlled cord traction
- Bladder emptying
What is the plane of separation of the placenta?
Spongy layer of decidua basalis
What are the mechanics of placental separation?
Shearing force
What is a normal volume of blood loss?
500ml
When is blood loss abnormal?
- if >500mls, more significant if >1000ml
- any blood loss in labour prior to delivery apart from ‘show’ is considered abnormal and requires referral to a consultant unit
How is haemostasis achieved?
- tonic contraction
- lattice pattern of uterine muscle strangulates the blood vessles
- thrombosis of the torn vessel ends
- pregnancy is hyper-coagulable state
- myo-tamponade-opposition of the anterior/posterior walls
What is the puerperium?
Period of repair and recovery
6 weeks of return of tissues to non-pregnant state
What happends during the puerperium
- lochia: vaginal discharge containing blood, mucus and endometricla castings
- rubra: fresh red 3-4days
- serosa: brownish red, wattery 4-14 days
- alba (yellow) 10-20 days
- bloodstained discharge lasts for about 10-14 days following birth
What uterine changes happen in the puerperium?
Uterine involution
Weight reduction from 1000gms to 50-100grms
Fundal height- umbilicus to within pelvis in 2 weeks
Endometrium regenerates by the end of a week (except the placental site)
When does physiological diuresis occur?
2-3 days postnatally
What initiates lactation?
Placental expulsion and a decrease in oestrogen and progesterone
How do oestrogen and progesterone block milk production?
Block the release of prolactin form the pituitary gland and make the mammary cells unresponsive to this pituitary hormone
Why is colostrum important
Rich in immunoglobulin
