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
What does membrane sweeping involve?
A vaginal examination and a finger is inserted through the cervical os, where a circular sweeping movement is performed
This separates the membranes from the uterine wall
This action allows endogenous prostaglandins to be released
May cause discomfort, pain or bleeding
Usually kickstarts labour within 48hrs (70%)
What score is used to assess the status of the cervix?
Bishop score
What features are included on the bishop score?
1) Dilatation
2) Length of cervix
3) Station
4) Consistency of cervix
5) Position of cercvix
How are bishop score interpreted?
Lower score = the more unfavourable the cervix
5 or less = ‘unfavourable’
- Labour unlikely to start without induction
9 or more = ‘favourable’
- Labour will likely start without induction
What is priming of the cervix?
Done in response a an unfavourable bishops score (however often down either way)
Prostaglandins inserted into posterior fornix of the cervix
- PgE2
Dose can be repeated
What dose and route of prostaglandins are available to prime the cervix?
All are dinoprostone (PgE2)
1) Propess - 10mg released over 24hrs
2) Prostin gel - 1mg or 2mg released over 6 hours
3) Prostin tablet - 3mg released over 6 hours
What may take place following a prostaglandin application?
Amniotomy = Artificial rupture of membranes (ARM)
After 4hrs of 2nd dose of prostaglandins
What does ARM involve?
Takes place once the cervical opening is sufficiently open
Involves artificially breaking the water by carefully placing a small hook up through the neck of the womb in order to rupture the membranes
This causes a release of natural prostaglandins from the area which may help labour
What may take place if a membrane sweep, prostaglandins and ARM have not induced labour?
Oxytocin therapy
What does oxytocin therapy involve?
Type of medication which stimulates contraction strength and frequency
Given IV
Continuous CTG required
What is the maximum number of contractions / 15 minutes that is aimed for in oxytocin therapy?
No more than 6 contractions in 15 minutes
What are some possible complications of IOL?
1) If it fails may need a CS
2) Uterine hyperstimulation, fetal distress and hypoxic damage to the baby
3) Uterine rupture (esp multiparous women)
4) Intrauterine infection with prolonged membrane rupture without delivery
5) Prolapsed cord can occur with first rush of amniotic fluid if presenting part is not well engaged
6) Amniotic fluid embolism
7) 1.5x inc risk of operative vaginal delivery and 1.8x inc risk of CS
How may prostin gel application vary between primips or multips?
For a primip = 2mg doses 6hrs apart (in mean time woman can be sent home to wait for labour to begin)
Multip may only need 1mg or one dose
Primip are more likely to need 2 or 3 full 2mg doses
What is preterm labour?
Spontaneous labour <37 weeks
What can be offered to try to prevent preterm labour?
Progesterone - vaginal or IM
Cervical cerclage
What is the course of action if a woman presents preterm with clear fluid leakage (no contractions)?
Speculum examination
- Do not do a VE (if membranes have ruptured this could cause infection = chorioamnionitis)
If pooling of amniotic fluid = diagnostic of pre-term pre-labour rupture of membranes (PPROM)
If no pooling then need further testing
What further testing may be needed if there is no pooling of amniotic fluid following a woman presenting preterm clear fluid leakage?
Insulin-like growth factor binding protein-1 test
or
Placenta alpha-microglobulin-1 test
Either positive = PPROM
What may be considered in women who are between 16+0 and 27+6 with a dilated cervix and exposed, unruptured fetal membranes?
Rescue cervical cerclage
What are CI for a rescue cervical cerclage?
Signs of infection, bleeding or uterine contractions
How is preterm labour diagnosed?
Symptoms of preterm labour (ie abdo pain that may be suggesting contractions)
If membranes intact - speculum and digital VE can be performed
How common is preterm labour?
6% before 37 weeks
2% before 34 weeks
What are some risk factors for preterm labour? (5)
1) Prev preterm labour
2) Multiple pregnancy
3) Polyhydraminos
4) Antepartum haemorrhage
5) Uterine abnormalities
What are some causes of preterm labour?
1) PROM
2) Maternal pyrexia eg UTI
3) Fetal death in utero
4) BV
5) Cervical incompetence
What is the management of ongoing preterm labour with intact membranes?
Full electronic monitoring
Tocolytic agents - prolong pregnancy by approx a week
- Usually given for 48hrs to allow time for steroid therapy to act / for the woman to transferred to a hospital with a NICU
- Uterine muscle action inhibitors may be used (prgesterone)
Give some examples of tocolytic agents
Nifedipine Beta agonists Ritodrine NSAIDS Oxytocin agonists - atosiban
What are some CI to tocolysis?
Thyroid disease Cardiac disease Severe HTN (>1160/110mmHg) Sickle cell disease Chorioamnionitis Intrauterine death
Relative - advanced labour, APH, maternal DM
What are some side effects of tocolysis?
1) Tachycardia - stop if maternal pulse >120bpm
2) Hyperglycaemia - beta agonists and steroids are both diabetogenic, check glucose 2hrly and start sliding scale of insulin if >9mmol/l
3) Pulmonary oedema - caused by fluid overload and tachycardia. Avoid by giving through syringe driver to reduce amount of fluid given
What are the benefits of steroid therapy?
Reduce the incidence and severity of IRDS in fetuses born between 26 and 36wks gestation
Also reduce risk of intracerebral haemorrhage in babies born <34wks
NB given alongside tocolysis, pregerably 48hrs before delivery
What is the management of PPROM >34 weeks?
Must balance risk of preterm delivery vs risks of intrauterine infection (chorioamniotitis)
Either immediate delivery, or if no signs of choramnionitis, manage conservatively
Conservative management - steroids and prophylactic erythromycin 250mg QDS for max 10 days or until the woman is in established labour
- Penicillin if cannot tolerate
- Send home and safety net
What safety netted is offered in the conservative management of PPROM >34wks?
- Check temp 4-5 times / day
- Check for abdo tenderness
- Purulent discharge from vagina
- Malaise
- Reduced fetal movements
What is the management of PPROM <34wks?
Monitor for signs of chorioamnionitis CTG NICU Corticosteroids Erythromycin IOL if chorioamnionitis
Tocolysis not recommended (does not improve perinatal outcomes)
What are some complications of PROM?
Cord prolapse (rare) - due to transverse lie or breech
Neonatal infection - increased by VE, GBS and inc duration of fetal membrane rupture
What is the management of PROM?
Confirm PROM, check lie and presentation
Avoid VE unless risk of cord prolapse (ie abnormal lie or foetal distress)
HVS to screen for infection
CTG
Either await spontaneous labour or IOL
- 80% will labour spontaneously in 24hrs
- After 18hrs give prophylactic abx
Monitor maternal pulse, temp and fetal HR every 4hrs
- Presence of meconium in liquor or evidence of infection warrants IOL
What are the 3 x P’s of labour?
1) Power
2) Passage
3) Passenger
What is the power in terms of mechanism of labour?
The degree of force expelling the uterus
Once labour is established the uterus contracts for 45-60s every 2-3 minutes
The pulls the cervix up and causes dilation, aided by the pressure of the fetal head on the cervix
The contractions progress from the uterine fundus towards the cervix, helping to expel the fetus
When may poor uterine contractility be seen?
Nulliparous women and IOL
Not in multiparous women
What is the passage in terms of mechanism of labour?
The dimensions of the pelvis and resistance of soft tissues
What is the passenger in terms of mechanism of labour?
The diameters of the fetal head
What does routine monitoring include in labour?
1) BP, pulse, temp, urinalysis (intermittently)
2) Vaginal losses
- Liquor = clear, meconium, blood stained
- Fresh blood
- Show = pink/white cervical mucus plug
3) Contraction freq, stength and length
4) Abdo palpations and VE to determine progress
5) Intermittent foetal HR via Pinnard stethoscope or doppler
What us a partogagram?
Used to record progress in labour
What features are included on a partogram?
1) High risk factors - obstetric, paediatric or anaesethetic
2) Foetal HR
3) Cervicgoram - cervical dilation marked by a cross
4) Descent of foetal head - marked by a circle (every hr by an abdo exam, every 3-4hrs by VE)
5) Freq, strength and duration of contractions
6) If membranes ruptured - colour of amniotic fluid
7) Volume of maternal urine, tested for ketones and urine
8) Record of drugs given eg analgesia, oxytocin
9) Maternal BP, HR, temp
What are some common causes for failure to progress in labour in terms of the 3 x P’s?
Power - inefficient uterine contractions eg in nulliparous / IOL
Passenger - fetal size, disorder of rotation (eg occipitoposteror), disorder of flexion (eg brow presentation)
Passage - cephalopelvic disproprotion, possible role of cervix
What are some non-pharmacological options available for pain relief during labour? (7)
Transcutaneous electrical nerve stimulation (TENS) Massage Relaxation Breathing Water - reduces pain during 1st stage Mobilisation Hypnotherapy
What pharmacological options are available for pain relief during labour? (4)
Paracetamol
Nitrous oxide
Opiates
Nerve blocks
What inhaled agents can be used for analgesia in labour?
Entonox = mixture of nitrous oxide and oxygen
Rapid onset and mild analgesic
What are some side effects of entonox?
Light headedness
Nausea
Hyperventilation
What systemic opiates may be used for analgesia in labour?
Pethidine, diamorphine or morphine
Used as IM injections / patient controlled injections
Why should systemic opiates not be used within 2 hours of delivery?
As they depress the neonatal respiratory centre
may require reversal with naloxone
What nerve blocks are available for analgesia in labour?
Local:
- Pudendal block
- Field block
Regional
- Spinal block
- Epidural
General anaesthesia
How and when is a pudendal nerve block given?
Pudendal nerve blocked with xylocaine as it branches traverse the ishical spine
- Given through the vaginal wall or perineal skin
Only numbs area of perineum supplied by pudendal nerve so a field block may also be required
Used for outlet manipulations in the 2nd stage eg forceps delivery
What areas does field block numb? When is it given?
Local infiltration to the nerve endings in the vulva and labia
Used for episiotomy / episiotomy repair or as an adjunct to a pudendal block
What is a regional nerve block?
Nerve roots blocked at their origin from the spinal chord
When is a spinal block used?
Not commonly used in normal labour
More often used for a CS (elective and emergency) - rapid onset of reliable block
What is the method for a spinal block?
Heavy bupivacaine injected into subarachnoid space at L3-L4
Woman in head up position
Blocks nerve roots L2-S1
NB an epidural catheter may be sited at the same time for postoperative pain relief (CSE = combined spinal and epidural pain relief)
What are some side effects of a spinal block?
Drop in maternal BP and transient foetal tachycardia
What is the most commonly used analgesia in labour?
Epidural
40% overall, 55% nulliparous
Esp good in prolonged labour
What is the method of an epidural?
Bupivicaine 1% via epidural catheter into epidural space
Affects nerve roots L2-S4
Rapid pain relief lasting 2-3hrs
What are some disadvantages of an epidural?
Requires increased monitoring of BP and HR
- Reduce BP due to autonomic pathway)
Women often bed bound
Reduced bladder sensation which can lead to urinary retention
Reduced urge to push during active 2nd stage
Risk of Post-Dural Puncture headache, infection and haematoma
When is a GA used for analgesia in labour?
Avoided if at all possible
Used in emergency CS if there is insufficient time to do a spinal block
What is the risk of using GA for analgesia in labour? How is this avoided?
Aspiration
- Empty stomach using NG tube
- Give sodium citrate or a H2 receptor blocker (ranitidine)
- Use cricoid pressure and RSI (rapid sequence intubation)
What counselling may need to be given surrounding common myths of regional nerve blocks?
They do not prolong labour
They do not inc risk of CS
No evidence that they cause chronic back pain (some women have chronic back pain following labour but this is probably due to the labour itself)
What is a contraindication of a regional nerve block?
Increased risk of bleeding - can lead to a haematoma forming around the spinal cord leading to cord compression
Cannot be used in women with pre-eclampsia as there is an association with low levels of platelets (HELLP syndrome)
