Labour Flashcards
What initiates labour?
increased oestrogen
decreased progesterone
myometrial stretch increases excitibility of myometrial fibres
mechanical stretch of cervix and stripping of foetal membranes helps
Fergusons reflex
What is Fergusons reflex?
fetal distention of the cervix or vaginal walls stimulates a neuroendocrine response that leads to oxytocin production which leads to contraction of the uterus
How does progesterone act in labour?
keeps the uterus settled
prevents the formation of gap junctions
hinders the contractibility of myocytes
How does oestrogen act in labour?
makes the uterus contract
promotes prostaglandin production
How does oxytocin act in labour?
initiates and sustains uterine contractions
acts on decidual cells to promote prostaglandin release
increase of receptors in myometrial and decidual tissue towards the end of pregnancy causes increased phospholipase C activity which increases Ca and contractibility
Where is oxytocin synthesised?
in decidual and extraembryonic fetal tissues and in the placenta
How does pulmonary surfactant help in labour?
stimulates prostaglandin synthesis
What does fetal cortisol do to the mother?
increases oestrogen
What cervical changes happen during labour?
increase in hyaluronic acid gives increase in molecules among collagen fibres
decrease in bridging among collagen fibres gives decrease in firmness of cervix
How does cervical ripening happen?
decrease in collagen fibre alignment and strength
decrease in tensile strength of cervical matrix
increase in cervical decorin
What type of collagen makes up the cervix?
type 1,2,3,4
What does a high Bishops score indicate?
more likely to go into labour
What 5 elements make up the Bishops score?
position effacement dilation station in pelvis consistency
What makes up the first stage of labour?
latent and active phases
Describe the latent phase?
mild irregular uterine contractions
cervix shortens and softens
may last a few days
Describe the active phase?
4cm -> full dilation
contractions become more rhythmic and stronger
slow descent of the presenting part
What is normal progress during the active phase?
1-2cm per hour
What makes up the second stage of labour?
full dilation (10cm) -> delivery of the baby
In nulliparous (first time) pregnancy when is 2nd stage of labour considered prolonged?
if exceeds 3 hours with analgesia
2 hours if no analgesia
In multiparous (previous) pregnancy when is 2nd stage of labour considered prolonged?
> 2 hours with analgesia
>1 hour without
When should the membranes rupture?
just before labour
What comprises the third stage of labour?
delivery of the baby to expulsion of the foetal membranes and placenta
What is the average duration of the third stage of labour?
10 mins
can be anywhere between 3 mins -> longer
What happens if the third stage is still going on after 1 hour?
removal under general anaesthetic
What is the expectant management of the third stage?
spontaneous delivery of the placenta
What is the active management of the third stage?
use of oxytocic drugs and controlled cord traction = lowers the risk of PPH
What are Braxton Hicks contractions?
false contractions - tightening of the uterine muscles to prepare the body for birth - they are irregular
more likely in those that have had children before
How do you stop Braxton Hicks contractions?
with ambulation or change in activity
What causes true labour contractions?
release of oxytocin
What are true labour contractions?
Regular, evenly spaced - time gets shorter between them
length of time of contraction also increases and pain increases too
What is the pathway of true labour contractions?
starts in the fundus then spreads down each side symmetrically - pushing the baby towards the birth canal
What can be given for pain relief for true labour contractions?
paracetamol -> cocodamol -> diamorphine
etonox (gas and air)
can also give a spinal/epidural
What are the 3 key parts to labour?
Power
Passage
Passenger
What determines the power of labour?
uterine contractions
- uterine muscle = smooth muscle, highest density at the fundus
- pacemaker = region of tubual atresia, synchronised waves from both astia
- polarity = upper segmant contracts + retracts and lower cervix stretches, dilates and relaxes
- frequency = normal = 3-4 in 10mins, 10-15 secs are start (max = 45secs)
What determines the passage of labour?
maternal pelvis
- gynaecoid pelvis = most suitable
- arthropoid = oval shape
- android = triangular/heart shaped - African/carribean women
What determines the passenger for labour?
fetal position
normal = longitudinal lie, cephalic presentation, occipital-anterior, head engages occipito-transverse, flexed head
abnormal = breech presentation, transverse lie, oblique position - occipito anterior
Describe engagement - the 1st cardinal movement of labour?
fetal head engaged when the widest diameter of the head has entered the brim of the pelvis - 3/5ths entered, 2/5ths still felt abdominally
Describe descent - the 2nd cardinal movement of labour?
dowards passage of the presenting part through the pelvis
Describe flexion - the 3rd cardinal movement of labour?
flexion of the foetal head occurs passively as the head descends due to the shape of the bony pelvis and resistance offered by soft tissues
Describe internal rotation - the 4th cardinal movement of labour?
rotation of the presenting part to the anterior position as it passes through the pelvis
What happens if the head does not internally rotate?
need to do a mediolateral episiotomy
Describe extension - the 5th cardinal movement of labour?
occurs once the foetus has reached the level of the opening of the vagina
it brings the base of the occiput in contact to the inferior margin at the symphysis pubis
Describe external rotation - the 6th cardinal movement of labour?
return of the foetal head to the correct anatomical position
Describe expulsion - the 7th cardinal movement of labour?
delivery of the baby
What is crowning?
appearance of a large section of the foetal head at the introitus (vaginal opening)
labia are stretched to full capacity
burning and stinging feeling for the mother
How long should cord clamping be delayed by? Why?
3 minutes
to increase the red blood cells that the baby recieves by 50%
How long should skin to skin be done after birth?
1 hour
What are the signs of the 3rd stage of labour?
5-10 mins after delivery
uterus contracts, hardens and rises
umbilical cord lengthens permanently
frequently gush blood immediately before
What is the active management of the 3rd stage of labour?
prophylactic administration of Syntrometerine or Oxytocin 10 units
also do cord clamping and controlled cord traction and bladder emptying
What are two methods of placental separation?
Matthew Duncan
Schultz
What is normal blood loss in labour?
<500mls
What blood loss contitutes giving medication?
> 800mls
What is the puerperium?
6 week period of recovery and return of tissues to non pregnant state
What is lochia?
vaginal discharge containing blood, mucus + endometrial castings
What are the different types of lochia?
rubra - fresh red - 3-4 days
serosa - brownish red - 4-14 days
alba - yellow - 10-20 days
How does the uterus change in the puerperium?
weight reduces from 1000gms -> 50-100 gas
endometrium regenerates in a week
vagina, cervix and perineum regress but not to the same as the pre pregnancy state
fundal height goes back to the pelvis within 2 weeks
physiological diuresis - 2-3 days post natally
