Intrapartum Flashcards
RANZCOG recommendations
for birthing unit
Where on-site services cannot be provided, women should be informed of the limitations of services available and the implications for intrapartum and postpartum care
Formal systems for safe and timely transfer
Amongst women selected for low obstetric risk, ~25% will develop peripartum complications necessitating transfer to an obstetrician led services
Timely access to - obstetric, midwifery, neonatal / paediatric, anaesthetic, operating theatre, resuscitation services
Further requirements: - ICU consultation, haematology, blood bank
Audit of outcomes and intervention
RANZCOG recommendations for labour care
Partogram
Routine obs on EWS
Women should be encouraged to ambulate freely according to comfort, where it does not compromise maternal and fetal observations in labour
- Cochrane 2013 - first stage of labour may be approx 1h 20m shorter for women who are upright or walk around
VE within 4h of arrival
Most trials do 2 hourly cervical assessments
Compromise: 4 hourly VE
Encourage clear fluids and light diet in active phase of labour to minimise risk of aspiration pneumonitis
All women should give birth in a position where they can rapidly access treatment in the event of sudden unexpected complications
RANZCOG post-partum recommendations
“Active” management of third stage is recommended for all women
Skin-to-skin contact should be facilitated as appropriate
Provide debriefing opportunities following adverse outcome or experience not meeting expectations
Delayed cord clamping benefits
75% of blood within 1st min, no increase in PPH
In term infants - increased hot, reduced iron deficiency at 6/12
- However increased polycythaemia and jaundice
Preterm
- Reduced transfusion, infection, NEC, IVH
Failure to progress
- 1st stage before established
No upper limit to the length of the ‘latent phase’ can be defined
Not uncommon for labour to stop and start before finally established
Recurrent or prolonged episodes of spurious labour may contribute to a legitimate decision for IOL in some women
Failure to progress
- 1st stage labour
PRIMIP
10th centile for progress of cervical dilatation in labour is 0.9 cm/hour (primigravida)
Threshold at which slow cervical dilatation merits a recommendation for oxytocin:
- Individualised with an informed discussion with the woman
- Commonly 1cm/hr for most women in spontaneous labour
- May be as high as 1cm / 2hr in women prioritising low intervention
MULTIP
10th centile for progress of cervical dilatation is 1.2cm/hr (multigravida)
Caution for augmentation as increased risk of uterine rupture compared to primigravida
Failure to progress
- 2nd stage
Progress includes flexion, rotation and descent
Normal for primigravida = up to 2 hours
Normal for multigravida = up to 1 hours
Factors contributing to labour
Passage
- Size of maternal pelvis
- Compliance of the cervix and soft tissue
- CPD
Passenger
- Size of fetal head
- Presentation and position of fetus
- Degree of fetal moulding
- Malpresentation, malposition
Powers
- Efficiency of uterine contractions. Effective UA is generally sustained for >40s
- Inadequate UA, dehydration, epidural
Dimensions of the maternal pelvis
Transverse diameter AP diameter
Pelvic inlet 13 11
Mid pelvis 12 12
Pelvic outlet 11 13
Pelvic inlet - transverse > AP, therefore foetus enters transverse and rotates (widest foetus diameter, is the AP)
Diameter names and dimensions for different presentations
Vertex - flexion of the fetal head
Suboccipitobregmatic (9.5cm)
- Below the occiput to the centre of the anterior fontanelle
Face
Submentobregmatic angle (9.5cm)
- Angle between the neck and chin and the centre of the anterior fontanelle
Deflexed OP
Occipitofrontal (11.5cm)
- Occiput to the root of the nose
Brow
Mentovertical (13-14cm)
- Chin to the centre of the sagittal suture
Incidence of malpresentations
OP 10% at the start of labour Brow 0.2% Shoulder 0.3% Breech 3% Face 0.2%
Mechanism of OP in labour
Deflexion occurs due to:
- the opposition of the fetal and maternal spines
- The longer BPD enters the narrower part of the pelvis while the bitemporal diameter enters the wider part.
As a result of this deflexion the occipito-frontal diameter (12.5cm) enters the pelvis leading to delayed engagement.
Next depends on what enters pelvis first (as will rotate anteriorly) and therefore the extent of deflexion.
90% of cases occiput meets pelvic floor first and anterior rotation and flexion will occur = OA
10% of cases head will rotate into OT arrest or remain OP
- obstruction requiring c-section, manual rotation or instrumental delivery
- If vaginal delivery increased chance of perineal trauma as vulva and perineum distended and stretched by occipito frontal diameter
Face presentation
Result of hyper-extension of neck
Presents submentobregmatic which is similar size to OA presentation
SVB possible if chin anterior = mento-anterior
- MAD = mentoanterior delivers
- Oxytocinon can be used to increase flexion
- Forceps can be used but ventouse, FBS or FSE contraindicated
- Will have considerable bruising and facial oedema postnatally
Mento-posterior –> indication for CS
Brow presentation
Very deflexed head in mentovertical position
Usually needs c-section
Can have vaginal delivery if very small fetus or multip
Bishop score
Score from 0-3 for: Dilatation (cm) Length (cm). Consistency Position Station
Moulding definitions
0 - Bones are separated and the sutures can be felt easily
1+ - Suture lines touch
2+ Suture lines overlap and are reducible easily with pressure by your finger
3+ Suture lines overlap and are irreducible
Second stage pushing
Delaying active pushing until the woman has an involuntary urge or the fetal head is visible on the perineum has been shown to reduce the incidence of forceps delivery, the need for caesarean section and it also shortens the active bearing down phase of the second stage
The use of sustained valsalva bearing down efforts is associated with lower fetal pH and higher fetal pCO2 levels
Steps of labour
Descent Engagement Neck flexion Internal rotation Crowning Extension of presenting part Restitution
Role of hormones in labour
Oestrogen
- From 37 weeks levels of oestrogen > progesterone this increases sensitivity to and stimulates release of oxytocin and prostaglandins
Oxytocin
- Released by maternal pituitary, causes contraction of myometrial cells
Prostaglandins
- Released by myometrium in response to cervix stretching, stimulate myometrial contractility by sensitising myometrial cells to oxytocin
- Prostaglandin + oxytocinon = positive feedback loop of increasing cervical stretch and therefore increasing release of PG and oxytocinon causing escalating intensity of contractions
Relaxin
Glucocorticoids
Contraindications to tocolysis
Maternal cardiac disease
Hypertension
Placental abruption
Evidence for water immersion
Cochrane review
- Water immersion in the first stage a/w significant reduction in epidural / spinal / paracervical analgesia / anaesthesia rate
- Reduction in duration of the first stage of labour (mean difference 32.4 mins)
- 1 trial found significantly higher level of satisfaction with the birth experience
Evidence for water birth
Concerns have been raised about fetal safety and drowning
No evidence of increased maternal, fetal or neonatal risk
- Further research warranted
Observational evidence suggests that if conducted according to a protocol and women appropriately selected, waterbirth can be achieved safely
Cochrane
- No difference in assisted delivery rate, CS, use of oxytocin, perineal trauma or maternal infection
- No differences in Apgar scores <7 at 5 mins, NICU admissions, neonatal infection rates
Issues to consider with water birth
Fetal surveillance should still occur as per RANZCOG recommendations
VE to assess progress may be performed under water if deemed necessary
- There is no quality evidence attesting to the safety of VE whilst immersed in water
Oxytocin augmentation of labour may not be possible
Third stage
- No reliable evidence to establish risks and benefits
- Theoretical risks of water embolism
- Best practice - assist to exit pool after birth where can manage third stage and accurately assess blood loss
Positive GBS swabs are not a primary contraindication
Women with PROM (>18h) may utilise water immersion during labour and birth provided IV Abs are administered
ARM evidence for slow progress
Consider if delay in first stage, if no further change after 2h, then consider synt
Evidence that routine ARM shortens labour is largely lacking
Oxytocin evidence in slow progress
No significant difference in rate of CS or instrumental delivery
Reduces the duration of labour by a mean of 2h, but does not increase the vaginal birth rate
No difference in maternal or neonatal outcomes
Incidence of prelabour SROM
Prelabour ROM - 1 in 12 pregnancies
Most commonly >37/40
Incidence of term PROM = 8%
Spontaneous labour follows at:
- 24h in 70%
- 96h in 95%
Statistically significant improved outcomes with IOL in TERM PROM
Clinical chorioamnionitis Intrapartum fever Postpartum fever Antibiotics before / during labour Neonatal antibiotics NICU stay
Cochrane 2017 - Planned early birth vs expectant management for PROM at term
Planned early birth:
- Reduced risk of maternal infectious morbidity (chorioamnionitis, endometritis)
- Neonates less likely to have definite or probably early-onset neonatal sepsis
- Women had significant reduction in chorioamnionitis and postpartum septicaemia
- Neonates less likely to receive antibiotics and require admission to NICU
- Women had more positive experiences
- Non-statistical reduction in definite early-onset neonatal sepsis and perinatal mortality
No increase in CS - Planned early birth associated with a non-significant trend toward reduced CS rate
Criteria for expectant management
for PROM
Term PROM with fixed cephalic presentation
GBS negative
No meconium stained liquor
No signs of infection - Maternal tachycardia, fever, uterine tenderness
Normal CTG
No Hx of digital VE, cervical suture
Adequate resource / staffing to provide support as an outpatient or inpatient
Commitment to 4 hourly maternal temperature, evaluation of vaginal loss and assessment of fetal wellbeing
Antibiotics If GBS negative and PROM
Routine antibiotics
- In those with PROM after 36/40, non-significant reduction in chorioamnionitis, endometritis, and neonatal sepsis
- Benefits need to be weighed against increased risk of resistance
Antibiotics after 12h
- In women with latency >12h, prophylactic Abs associated with significantly lower rates of chorioamnionitis by 51% and endometritis by 88%
Offer antibiotic prophylaxis to women who are in active labour and have had SROM for >18h
If labour is induced with PG gel, start at time of first VE
PROM -
IP or OP
Expectant management at home associated with a further increase in risk of maternal need for antibiotics and neonatal infection
Careful selection of those managed at home
- Education about signs of infection
- Should live close to the hospital
- Adequate support at home
- Dependable transport
Ability to check temperature and HR every 6h
IOL method for PROM
Offer IOL within 24hr of SROM
Limited evidence on prostaglandins (Prostin, Cervidil or misoprostol) vs oxytocin
- Failed to show clear benefit
Cochrane meta-analysis, 2000
- Suggested increased risk of chorioamnionitis and neonatal infection with prostaglandins
Oxytocin remains the method of choice for most RANZCOG fellows
In subset of women with unfavourable cervix, prostaglandins may have an important role
- Trial with one dose of dinoprostone followed by oxytocin 6h later in women with BS <5 resulted in significantly increased rate of vaginal delivery within 24h
Maternal age and IOL
AMA associated with increased antenatal and intrapartum stillbirth and neonatal mortality
Risk of stillbirth:
- <35y = 0.75 per 1000
- >40y = 2.5 per 1000
Offer at 39-40 weeks for women >40y
Contraindications to IOL
ABSOLUTE:
Placenta praevia / vasa praevia
Transverse lie
Prolapsed umbilical cord
Active genital herpes (first episode in third trimester)
Previous classical uterine incision
Maternal or fetal anatomical abnormality that contraindicates vaginal delivery
RELATIVE:
Triplet or higher order multiple pregnancy
Breech presentation
2+ previous LSCS
Australia Safer Baby Bundle position elements:
- Supporting women to stop smoking in pregnancy
- Improving detection and management of FGR
- Raising awareness and improving care for women with decreased FM
- Improving awareness of maternal safe going-to-sleep position in late pregnancy
- Improving decision-making about the timing of birth for women with risk factors for stillbirth
- Target according to individualised risk
- Consider possible adverse consequences of planned birth <39/40
Factors increasing the likelihood of CS for failed IOL and dystocia
Nulliparity Increased maternal age Increased maternal BMI Previous CS Earlier gestation Unfavourable cervix
Complications of IOL
Hyperstimulation
- 1-5% of PG induced labour
- Tocolytic treatment successful in normalising UA and reversing FHR abnormality in 98%
Fetal distress
Failed IOL
C-section
Lower CS rates in IOL for: - Prolonged pregnancy - Gestational HTN and mild PET - Maternal request IOL at or beyond term No increased risk of CS in IOL for: - Maternal diabetes - Twin pregnancy - PROM - FGR - Suspected fetal macrosomia Increased risk of CS: - IOL <34/40 for severe PET
Pros and cons of mechanical methods
Advantages:
- Simplicity of procedure
- Lower cost
- Reduction of side-effects from medical treatments
Disadvantages:
- Difficulty in inserting through an unfavourable cervix for the operator and discomfort for the woman
- Risk of infection
- LLP is a contraindication
Cochrane review 2019
- Mechanical IOL with a balloon is probably as effective as IOL with vaginal PGE2
- Balloon seems to have a more favourable safety profile - Reduced hyperstimulation with FHR changes, serious neonatal morbidity or perinatal death. May reduce the risk of NICU admission
- Balloon catheter may be slightly less effective as oral misoprostol
- Probably increased CS for balloon vs. oral or pv miso
- increased vaginal delivery with po miso, uncertain with pv
ARM for IOL
Evidence that routine ARM shortens labour is largely lacking (Cochrane review 2009)
Risk of infection increased following rupture of membranes
ARM provides useful information on fetal wellbeing (liquor volume and colour)
ARM associated with more frequent use of oxytocin when compared to vaginal PGE2
Membrane sweep for IOL
Cochrane 2020:
- Membrane sweeping may be effective in achieving a spontaneous onset of labour, but the evidence for this was of low certainty
- When compared to expectant management, it potentially reduces the incidence of formal IOL
Cochrane 2005:
- NNT to avoid one formal IOL = 8
Prostaglandins for IOL
Prostaglandin E2 causes uterine contraction and softening of the cervix
Effective at increasing the odds of vaginal birth within 24h when compared with placebo
Reduced CS rates, epidural analgesia
Increased maternal satisfaction
No evidence of an effect on instrumental delivery
Hyperstimulation risk is up to 4.8% (vs. 1% with placebo or no treatment)
If previous CS, uterine rupture 2.5%
All types appear to be as efficacious as each other
Cochrane 2020 - OP vs. IP, similar outcomes
Women prefer to start IOL with PGE2 in the morning
Misoprostol pv vs. PG
Vaginal misoprostol is more effective at achieving birth within 24h
• But 3-fold higher risk of hyperstimulation (mainly due to doses >25mcg)
Use for IOL is off-label in Australia and NZ
Higher potency
• Therefore commonly use for midtrimester TOP or IUFD
Misoprostol benefits
Synthetic prostaglandin E1 analogue
Cheap
Stable at room temperature
Can be given orally, vaginally or sublingually
Vaginal: max 25mcg 4 hourly
Compared to placebo, vaginal misoprostol associated with:
- Reduced failure to achieve vaginal delivery within 24h
- Increased uterine hyperstimulation
Oral vs. vaginal misoprostol
- Lower CS rate
- Increased mec
- Less hyperstimulation
Miso vs. PG +/- oxy
Compared to PGE2 and oxytocin, vaginal misoprostol associated with:
- Less epidural use
- Fewer failures to achieve vaginal delivery within 24h
- More uterine hyperstimulation
Compared with PGE2, vaginal misoprostol associated with:
- Less oxytocin augmentation
- More mec
Oxytocin mode of action for IOL
Nonapeptide hormone
Produced in the hypothalamus and stored in the posterior pituitary gland
Acts on specific receptors on the uterus to cause uterine contractions
It takes 30-40 mins at a given infusion rate to achieve a “steady-state” plasma concentration of oxytocin
“Resting time” between contractions needs to be >60s or fetal hypoxia is likely
Dosage of oxytocin for augmentation
Recommend starting infusion at a rate of 1-2mU of oxytocin per minute, which is increased every 30 mins
Given by infusion pump or syringe driver
Increase dose until 3-4 contractions every 10 minutes
Most units dilute this using 10 IU of oxytocin in 500ml or 30 IU of oxytocin in 500ml (for latter the infusion rate in ml/hr = oxytocin dose in mU/min)
Maximum licensed rate is 20 mU per minute, though some units go up to 32 mU per minute
Use continuous EFM once syntocinon is commenced
Evidence for oxytocin vs. PG
Oxytocin inductions compared with vaginal prostaglandins, Cochrane 2009
Oxytocin only group:
• Increased unsuccessful vaginal delivery within 24h
• May increase rate of intervention in labour
• Increased epidurals when oxytocin alone was used
Risks of declining IOL for prolonged pregnancy
Fetal risks with declining IOL for prolonged pregnancy
- Stillbirth
- Macrosomia
- Birth injury
- Meconium aspiration syndrome
Maternal risks with declining IOL for prolonged pregnancy
- CS
- Perineal injury
- PPH
Gestation Stillbirth rate
37 weeks 1 in 1000
42 weeks 3 in 1000
43 weeks 6 in 1000
Risk factors for prolonged pregnancy
Obesity
Nulliparity
Maternal age >40y
After one post-term pregnancy, the risk of a second post-term birth is increased 2-4 fold
Fetal dysmaturity / postmaturity syndrome
Characteristics of chronic intrauterine malnutrition
Increased risk of umbilical cord compression due to oligohydramnios
Meconium passage is common
Long thin body, long nails, SGA
Skin is dry (vernix decreased or absent), peeling, appears loose
Risk of hypoglycaemia, polycythaemia, perinatal asphyxia, mec aspiration, persistent pulmonary HTN
Cochrane 2018
IOL at or beyond term compared with expectant:
Fewer
- Perinatal deaths
- CS
- NICU admissions
- Babies with low Apgar
More operative births
Cochrane review (2020) of IOL >37/40 mostly included trials with IOL after 41/40
- IOL associated with:
Fewer (all cause) perinatal deaths - clear reduction, thought absolute rates are small (0.4 vs 3 deaths per 1000)
- NNT 544
- 70% reduction
Fewer stillbirths
Probably fewer CS
Probably little or no difference in operative vaginal births
Little or no difference to perineal trauma
Little or no difference to PPH or breastfeeding at discharge
Lower rates of NICU admission
Probably fewer babies had Apgar scores <7 at 5 mins
Prevention of prolonged pregnancy
Use of routine USS in early pregnancy
- Reduces the prevalence compared with menstrual dating alone
- Early routine USS examination reduced the rate of intervention for post-term pregnancy by 40%
Membrane sweeping
- Offer from 38/40
Induction of labour
Signs of placental separation
Cord lengthening
- Progressive uterine retraction forces the placenta into the lower segment
Uterus becomes globular and firmer
Uterine rises in the abdomen
- Descent of the placenta into the lower segment and then vagina, displaces the uterus upwards
Gush of blood
Retroplacental clot escapes as placenta descends
Incidence of homebirth
<1% of births in Australia
Nearly 4% of NZ births
Factors critical to reducing potential adverse maternal and perinatal outcomes
for homebirth
Presence or not of complications that may increase maternal or perinatal risk above that inherent to all pregnancies
Access to a high standard of service and an integrated team of appropriately trained professionals
Access to consultation
Access to safe and timely transport to a nearby maternity hospital
RANZCOG position statement
Role is to aim for the best outcomes for mother and baby
Supports informed choice in all aspects of maternity care
College supports hospitals as the safest place for birth in Australia and NZ
Provide information free of prejudice and bias
Even if no complicating factors, the level of risk to mother and baby with homebirth is at a level that is unacceptable to most women
When a pregnancy has any factor that increases maternal or perinatal risk, home birth is particularly dangerous
Evidence for home birth safety
Limited data
Outcomes for planned homebirth are either similar to, or significantly higher than those reported hospital births
- Note that hospital population include some women at increased risk of obstetric complications, therefore expect planned homebirth group to have better outcomes by virtue of being selected for lower risk, therefore concerning to find similar outcomes when compared to higher risk population
Definition of shoulder dystocia
and incidence
Shoulder dystocia is any cephalic delivery where manoeuvres other than a gentle traction are required to deliver the baby after the head has delivered
0.58 - 0.70%
risk factors for shoulder dystocia
Conventional risk factors predict only 16% of shoulder dystocias that results in infant morbidity
At least 50% of pregnancies with shoulder dystocia have no identifiable risk factors
Previous shoulder dystocia - 20-fold increase risk
Macrosomia >4.5kg
- 48% of births complicated by shoulder dystocia occur with infants <4kg
- USS sensitivity for macrosomia is low (60%)
Diabetes mellitus (2-4 fold increase)
Maternal BMI >30
IOL
Multi parity
INTRAPARTUM Prolonged labour (esp second stage) Secondary arrest Oxytocin augmentation (???) Assisted vaginal delivery (ventouse > forceps)
Prevention of shoulder dystocia
No evidence that early IOL for macrosomia prevents SD
Elective LSCS - not recommended
EFW is unreliable and the majority of macrosomic infants do not experience SD
- NNT = 2345 to prevent one permanent injury from SD
ACOG recommend EFW >5kg should prompt consideration of delivery by CS
Diabetes:
- IOL is macrosomic - can reduce the incidence of shoulder dystocia
- consider el LSCS if EFW >4.5kg
Previous shoulder dystocia
- Recurrence rate reported between 1-25%
- Either CS or vaginal delivery can be appropriate - decision should be discussed with woman
Signs of shoulder dystocia:
Difficult with delivery of the face and chin
Head remaining tightly applied to the vulva or even retracting (turtle-neck sign)
Failure of restitution of the fetal head
Failure of the shoulders to descend
Routine traction in an axial direction can be used to diagnose shoulder dystocia but any other traction should be avoided
First line manoeuvres for shoulder dystocia
Call for help Discourage maternal pushing Lay woman flat McRoberts' Manoeuvre - Flexion and abduction of hips - Straightens the lumbosacral angle - Reported success rates as high as 90%
Suprapubic pressure
- Reduces shoulder diameter and rotates anterior shoulder into the wider oblique pelvic diameter
- No difference in continuous pressure and rocking
Consider episiotomy (for access)
Internal manoeuvres
- Rotational manoeuvres reported to be associated with reductions in both BPI and humeral fractures
Rotational manoeuvres
- Rubin II - fingers posterior to the anterior shoulder
- Wood screw - fingers are anterior to the posterior shoulder
- Reverse wood screw - fingers posterior to the posterior shoulder
Delivery of the posterior arm
- Reduces the diameter of the fetal shoulders by the width of the arm
- Incidence of humeral fractures 2-12%
- Neonatal trauma may be a reflection of the refractory nature of the case, rather than the procedure itself
‘All-fours’ technique
Third-line manoeuvres for shoulder dystocia
Cleidotomy - Surgical division of the clavicle or bending with a finger
Symphysiotomy - Dividing the anterior fibres of symphyseal ligament
- High risk of serious maternal morbidity and poor neonatal outcome
Zavanelli manoeuvre then CS
- Vaginal replacement of the head, then CS
- Success rates vary
- Maternal safety unknown
Posterior axillary sling traction (PAST)
- Suggested, but limited data
- Largest published case series - 14 liveborn cases with 1/3 having BPI and 15% had fractured humerus
- RANZCOG - PAST should not be attempted unless all standard efforts have been unsuccessful
Maternal outcomes of shoulder dystocia
PPH (11%)
Third and fourth degree perineal tears (4%)
Vaginal lacerations Cervical tears Bladder rupture Uterine rupture Symphyseal separation Sacroiliac joint dislocation Lateral femoral cutaneous neuropathy Psychological problems
