Intrapartum Care Flashcards
What is a term pregnancy?
Deliveries between 37 - 42 weeks
What physiological changes occur at the beginning of labour?
Initial release of a large amount of oestrogen
The oestrogen triggers the production of prostaglandins:
- Mediate the activity of labour
- Makes the body more sensitive to oxytocin
These chemicals have effects on the myometrium and cervix
What are the main changes to the myometrium at the beginning of labour?
The myometrium stretches and this increases muscle excitability and contractility
Oestrogen leads to the formation of gap junctions which makes the muscle better at transmitting signals preparing the uterus for contraction
The oestrogen makes the myometrium more sensitive to oxytocin
What are the main changes to the cervix at the beginning of labour?
There is a decrease in collagen and an increase in water content in the cervix making it more flexible and ready to stretch during labour
What are the two main phases of labour?
1) Latent phase of labour
2) Established phase of labour
What is the latent phase of labour?
This may go on for hours or even days and is not necessarily continuous
There may be some uterine cramping and contractions as well as some cervical effacement and dilatation UP TO 4CM
What is recommended for a woman do during the latent phase of labour?
Stay at home and care for herself
What is the established phase of labour?
Dilatation of 4cm and beyond
Regular and painful contractions
What is recommended for a woman to do during the established phase of labour?
Comes into hospital and receive 1-1 care from a midwife
What are the three stages of the established phase of labour?
1) Onset of established labour up until full dilation of the cervix (10cm)
2) Delivery of the baby
3) Delivery of the placenta
What is the effacement of the cervix? When does this occur?
The cervix is normally a long thin tube and it gets drawn up and flattened out to appear more like a disc that lies against the baby’s head
Occurs during the first stage of established labour (and to some extent during the latent phase)
What is the expected rate of dilation during the first stage of established labour?
Minimum of 2cm every 4 hours (or 0.5cm / hr)
- Often quicker for multiparous women
Average duration = 10hrs for nulliparous and 6hrs for meltiparous
How is the descent of the baby’s head measured?
Using ischial spines or seeing with how many fingers you can feel the baby’s head in the lower abdomen
Describe how ischial spines are used to determine the descent of the baby’s head
A baby is given a ‘station’
Station 0 = in line with the ischial spines
+1 - +3 if it is above
-1 - -3 if it is below
0 and below = delivery is imminent
Describe how using finger’s to feel the baby’s head is used to determine its descent
5/5 palpable - labour is still premature
1 or 0/5 palpable - labour is imminent
How can the duration of first stage of established labour be reduced?
Walking around and staying mobile
Women encouraged to do this although many do by themselves
This advice is only given to women that are low risk
How can stage 2 of established labour be divided?
Passive and active labour
What is passive labour?
The woman has fully dilated but there is not yet any involuntary or expulsive contractions
The head may be fully descended but the woman does not yet have the impulse to push and shouldn’t be encouraged to at this stage
What is active labour?
There are expulsive and involuntary contractions and the woman will have a strong urge to push / bear down
- Even if you haven’t seen full dilation women will begin to push even if told not to and there will be signs of a bulging perineum and anal dilation
Breathing should be controlled and the woman should not be necessarily pushing all the time to get the baby out ASAP
Normal duration = 40 min (nulliparous) or 20 mins (multiparous)
- Prolonged if >2hr in nulliparous or >1hr in multiparous
What problems can occur if a woman pushes too much / hurries through the active labour part of stage 2?
When a woman is actively pushing the fetus is less well oxygenated
Hurrying through the active stage does not give the perineum and other structures enough time to fully stretch - can lead to an increased chance of trauma
What is stage 3 of labour? What help may be required?
Delivery of the placenta
Usually happens naturally fine, but sometimes uretotonic drugs (eg syntometrine) used to help the uterus contract down which limits bleeding and helps with expulsion of the placenta
Normal blood loss = up to 500ml
Normally lasts = 15 mins (prolonged if >60min)
What is the benefit of deferring of clamping and cutting of the cord?
It can reduce rates of anaemia in the first 6 months of life
What are 4 things it is broadly important to monitor for the mother during labour?
Contractions
Vaginal examinations
Vagina loss
Vital signs
How is fetal monitoring performed for low risk women?
Intermittent auscultation of fetal heart using doppler US or Pinard stethoscope
How is fetal monitoring performed for high risk women?
Continuous CTG
Caridiotocograph
Summarise the stages and mechanisms of labour
1) Engagement in occipitotransverse (OT) position
2) Descent and flexion
3) Internal rotation - so baby faces occipito-anterior
4) Crowning
5) Extension - neck extends as the head is delivered
6) Restitution - head will re-align and turn either to the L or R
7) Delivery of the anterior shoulder
8) Delivery of the posterior shoulder
Describe why the baby initially internally rotates 90 degree
Superior opening of the pelvis, the birth canal = oval shape
Baby rotates 90 degrees to the L or R into a transverse position and begins to descend through the birth canal
Describe why the baby crowns
The centre of the birth canal = much more circular
Baby must lead with the narrowest part of its head - the occipit
The baby will flex its neck and the crown of its head will be the first to be born
Describe how the baby’s head is delivered
As the baby’s head descends into the inferior opening of the pelvis the aperture has changed shape and is widest longitudinally
Thus the baby’s head will rotate so that the baby is born facing the mothers back = occipito-anterior
As the baby’s crown emerges from the vagina the baby’s neck extends
What can happen if the baby’s head rotates so that it is born occipto-posterior (back to back)?
This can be a more painful and longer delivery
We can try to rotate the baby 180 degrees to make it face the right way eg with forceps
What happens once the baby’s head is delivered?
It will restitute after a few minutes
It will re-align with the body and so the baby’s head will rotate from looking posteriorly to looking either left or right
The head may be delivered for a few minutes before the rest of the body follows (should be within 1 or 2 contractions)
After restitution, what happens in delivery?
The anterior shoulder is delivered
Then the posterior shoulder is delivered
What is shoulder dystocia?
When the anterior shoulder becomes stuck behind the pubic symphysis
Can be assisted by wiggling the slightly anteriorly
What is induction of labour (IOL)?
What % of women are induced?
Artificial commencement of labour
Approx 24%
What are some indications for IOL?
1) Prolonged pregnancy
2) IUGR
3) PPROM (pre-partum rupture of membranes)
4) Antepartum haemorrhage - small, repeated blood loss
5) DM
6) Poor obstetric hx
7) Intrauterine death
8) Maternal HTN
What is considered prolonged pregnancy? Why may IOL be required?
> 41 weeks
Risk of stillbirth increases after 42 weeks (from 3/3,000 to 6/3,000)
When is it recommended that women with DM are induced? Why?
After 38 weeks
Due to increased change of placental insufficiency and increased likelihood of macrosomia
What are some absolute contraindications for IOL? (5)
1) Acute fetal compromise
2) Unstable lie - ie if the baby was transverse or not stable when you would induce
3) Placenta praevia
4) Pelvic obstruction
5) Severe cephalopelvic disproportion
What are some relative contraindications for IOL? (6)
1) Previous CS (scar may rupture)
2) Breech
3) Prematurity
4) High parity
5) Active primary genital herpes infection
6) Risk of cord prolapse
What is offered prior to formal IOL?
Membrane sweeping
When is membrane sweeping offered? (nulliparous + multiparous)
40-41 weeks if nulliparous
41 weeks for multiparous