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
Fetal outcomes of shoulder dystocia
Brachial plexus injury - 2.3 - 16%
- Most resolve without permanent disability
- <10% have permanent neurological dysfunction
- larger infants are more likely to suffer a permanent BPI
- Erb palsy (C5, C6) - Most common
Fractures
- Of the humerus and clavicle
- ~10%
Pneumothorax
Hypoxia brain damage
- Hypoxia related to shoulder dystocia is unlikely before 5 mins
Death ~0.4%
Intermittent auscultation recommendations
In labour
- Should occur during the contraction and continue for >30s after the contraction has finished
In active first stage of labour (from 4cm)
- At least every 15-30 minutes
In active second stage
- With each contraction or at least every 5 mins
Antenatal indications for Intrapartum CTG (FSEP)
Abnormal antenatal CTG Abnormal Doppler Suspected or confirmed IUGR Oligohydramnios or polyhydramnios Prolonged pregnancy (>42/40) Multiple pregnancy Breech presentation APH PROM (>24h) Known fetal abnormality which requires monitoring Uterine scar Essn HTN or PET Diabetes on medication, poor control, or fetal macrosomia Other current or previous obstetric or medical conditions which constitute a significant risk of fetal compromise (e.g. cholestasis, isoimmunisation, substance abuse) Reduced FM Morbid obesity (BMI >40) Maternal age >42y Abnormalities of maternal serum screening associated with increased risk of poor perinatal outcome (e.g. low PAPP-A or PIGF) Abnormal placental cord insertion Abnormal CPR
Intrapartum indications for CTG (FSEP)
IOL with prostaglandin / oxytocin Abnormal auscultation or CTG Oxytocic augmentation Regional anaesthesia Abnormal vaginal bleeding in labour Maternal pyrexia >38 Mec or blood stained liquor Absent liquor from amniotomy Prolonged first stage Prolonged second stage Preterm labour <37/40 Tachysystole Uterine hypertonus Uterine hyperstimulation
Considerations for continuous CTG in labour (FSEP)
Gestation 41+0 - 41+6 Gestation HTN GDM without complicating features Obesity (BMI 30-40) Maternal age 40-42 AFI 5-8cm or SDP 2-3cm
Maternal pyrexia 37.8-38
Disadvantages / limitations to continuous EFM
Reduced mobility
- May affect the woman’s ability to control and cope with pain
Possibility that woman will not be the centre of care in labour
Increased intervention
Variation in interpretation
Chorioamnionitis could make interpretation unreliable
Litigation - good record keeping is crucial
CTG vs. IA
No difference in perinatal mortality
Decrease neonatal seizures with CTG group
No difference in cerebral palsy
Increased rate of CS and instrumental delivery
No difference in cord blood acidosis
No difference in drugs for pain relief
Causes of reduced variability and accelerations in the fetus
Deep fetal sleep
- Most common cause
- Most fetuses have a sleep-wake cycle of around 20-40 mins
- Some fetuses may withdraw some parasympathetic input to the SA node –> minor rise in the baseline rate
Drugs and medication
Extreme prematurity
- Immature parasympathetic nervous system
Hypoxia
- Typically associated with other CTG abnormalities
4 things that affect baseline variability
Vagal effect on SA and AV node
- Acetylcholine
Adrenal medulla releasing epinephrine and norepinephrine
- Increase HR
- Catecholamines –> peripheral vasoconstriction –> increased BP
Chemoreceptors - influenced by products of metabolism
- high metabolic rates, and as a result have high oxygen requirements. Therefore are sensitive to falling oxygen levels
- Chemoreflex response is likely to be the key contributor to variable decelerations
Baroreceptors - Organs that are sensitive to stretch or pressure
- Primary role is to protect the fetal brain against excesses in pressure
Chemo and baroreceptors situated in:
- Carotid artery
- Arch of the aorta
- Brain stem
Medication effects on CTG
Beta blockers - Suppress sympathetic stimulation, lower baseline rate and accelerations of reduced amplitude,
- Typically do not reduce BV below the normal
Narcotics - may extended the periods of deep sleep in the fetus
Calcium channel blocks, particularly IV magnesium sulphate May reduce baseline variability - CCB, esp IV MgSO4 - LA in epidurals - Some AEDs - Some antipsychotic drugs - Steroids
Sympathomimetics (e.g. salbutamol or tebutaline)
- Increased sympathetic stimulation –> fetal tachycardia
Define tachysystole
Define hypertonus
Define hyperstimulation
More than 5 active labour contractions over a 10 minute period, without FHR abnormalities
Contractions lasting >2 mins or occurring within 60 secs of each other, without FHR abnormalities
Tachysystole or uterine hypertonus with FHR abnormalities
Early decals
Uniform in shape and repetitive Start and finish with the contraction Typically occur in sleep phase Often in the range of 4-8cm of dilatation Relatively uncommon Occur in 5-10% of intrapartum traces
Head compression –> Mild increase in intracranial pressure –> small reduction in FHR to compensate
Via vagus nerve
As the contraction eases, so dose the intracranial pressure –> FHR returns to baseline by the end of the contraction
Variable decels
Most common
Vary in depth, duration, timing
Typically have a rapid descent and recovery
Typically caused by cord compression
- Can occur in the absence of contractions
Overall, normal physiological response to cord occlusion
Chemoreceptors primarily involved
- acute fall in O2 –> reflex parasympathetic stimulation –> acetylcholine release –> rapid fall in FHR to reduces myocardial workload and prevents ischaemic damage
Pressure comes off cord –> withdrawal of PNS
Complicated variable decels
Rising baseline HR or baseline tachycardia
- foetus can’t increase SV, so increases HR to improve CO
Reduced or absent BV Persistent large amplitude (>60 bpm) Persistent long duration (>60s) Smooth post-deceleration overshoot Slow return to baseline
Late decels
Uniform in timing relative to the contraction
Repetitive in nature
Occur with each contraction
Usually no features of a well oxygenated fetus
Start after the start of the contraction
Bottom of the deceleration is usually >20s after the peak of the contraction
Return to baseline after the contraction has finished
Reduction in intervillous space blood flow with subsequent reduction in fetal oxygenation during and after the contraction
Sinusoidal pattern
on CTG
Oscillating pattern that is typically smooth and regular
- Regular in the timing of the oscillations, not amplitude
Usually has:
- Relatively fixed rate of 2-5 cycles per minute
- Amplitude of 5-15 bpm around the baseline rate
- Absent baseline variability
- No accelerations
Typically reflective of severe anaemia (Hb <60)
Represents a complete loss of autonomic nervous system control
Pathophysiology utilised in FBS
Abnormal (anaerobic) conditions
- -> lactic acid + H+ + 2-3 molecules of ATP
- Lactic acid diffuses slowly across the placenta –> metabolic acidosis
pH sampling requires more blood
- Increased chance of failed FBS
- Takes longer to take sample
Lactate - Equipment less expensive, low maintenance and more user friendly
No difference in outcomes between pH and lactate
Research suggests that FBS can reduce the intervention rate
- Instrumental birth and CS
Contraindications for FBS
Clear evidence of serious, sustained fetal compromise
Risk of fetal bleeding
- Haemophilia, alloimmune thrombocytopenia, chronic immune thrombocytopenia
Non-vertex presentation
Maternal infection
- HIV, HBV, HCV, active herpes
Prematurity - <34/40
FBS thresholds for management
> 4.8 mmol/L = <7.20
Warrant deliver
4.1 - 4.7 mmol/L = pH 7.2 - 7.24
Repeat sample in 30 mins
<4.1 mmol/L = >7.25
Repeat sample in 60 mins if FHR trace remains abnormal, or sooner if there are further abnormalities
Indications for paired umbilical cord blood gas or lactate analysis:
Apgar <4 at 1 minute
Apgar <7 at 5 mins
FBS performed in labour
Operative delivery was undertaken for suspected fetal compromise
Venous sample reflects maternal status
- Acts as the reference for the arterial sample
Arterial sample reflects fetal metabolic status at delivery
Fetal acidosis risks
Severe acidaemia with cord pH <7.0 is associated with an increased risk of neonatal death
Low pH with an abnormal base excess and bicarbonate level predicts the risk of HIE better than pH alone
If the base excess is less than -20 mmol/L, the fetus is at a more significant risk of seizures and HIE
If the base excess is -12 mmol/L or less, the fetus is at increased risk of admission to NICU
Huntley monitor
- STV
Normal >3 - 2% risk of metabolic acidosis, 0% IUFD
<2.6 - 10% will have metabolic acidosis, 25% rate of IUFD
Term breech implications
Study in Netherlands - 175 CS required to avoid one fetal death
Term Breech Trial has been criticised on methodological grounds
- Making its generalisability and applicability to appropriately staffed and resourced Australian and NZ hospitals uncertain
Recent meta-analysis (Berhan and Haileamlak, 2016)
- Absolute risks of perinatal mortality in planned vaginal group of 1 in 333, and planned CS group of 1 in 2,000
- Authors argue that absolute risks were very small, almost equivalent to a cephalic presentation at term
- However stated “informed parents may of course continue to choose vaginal delivery, but it is no longer justifiable for obstetricians to claim that in their hands there is no increased fetal risk from vaginal birth”
Alternatives to ECV for breech
There is no evidence that postural management alone promotes spontaneous version to cephalic presentation
Moxibustion - Chinese medicine, burnt on bottom of feet
- Thought to increase FM
Promotes conversion to cephalic, but poor quality data
Contraindications to vaginal breech delivery
Cord presentation
FGR (<10th centile) or macrosomia
Any presentation other than frank or complete breech (i.e. footling)
Extension of the fetal head
Clinically inadequate maternal pelvis
Fetal anomaly incompatible with vaginal delivery
Evidence of antenatal fetal compromise
Points about
Vaginal breech
Continuous CTG
Immediate availability of CS facilities, anaesthetist, and paediatric resuscitation
Availability of a suitably experienced obstetrician to manage the delivery
Risk of CS ~40%
IOL is not usually recommended
Epidural - may increase the risk of intervention
Semi-recumbent or all-fours position
To reduce the risk of cord compression, amniotomy is reserved for definite clinical indications
If slow progress, consider CS
FBS of the buttocks although technically possible, is not recommended
Principles for second stage in breech
Adequate descent of the breech in the passive second stage is a pre-requisite for encouragement of the active second stage
- allow descent of breech to perineum prior to active pushing
- If breech not visible within 2h of passive second stage, CS recommended
Hands off approach
Assistance, without traction - if delay or evidence of poor fetal condition
Tactile stimulation should be minimised - may result in reflex extension of the arms or head
Signs that delivery should be assisted:
- Lack of tone or colour
- Delay (>5 mins from delivery of the buttocks to the head, or >3 mins from the umbilicus to the head)
Semi-recumbent
- keep back anterior
- Manoeuvres
- Forceps
- Suprapubic pressure will aid flexion if there is delay due to an extended neck
All fours
- Evidence (limited) suggests spontaneous delivery without assistance will occur more often
Manoeuvres for breech
Pinard manoeuvre
- pressure on the popliteal spaceby the index finger while the other three fingers flex the leg while sliding it along the other thigh as the foot of the flexed leg is brought down and out
Lovset’s manoeuvre
- otation of the trunk of the fetus during a breech birth to facilitate delivery of the arms and the shoulders
- Ensure holding bones
Mauriceau-Smellie-Veit manoeuvre
- Palpating the fetal maxilla using the index and middle finger and gently pressing on the maxilla, bringing the neck to a moderate flexion
Bracht manoeuvre
- Delivery of a fetus in breech position by extending the legs and trunk of the fetus over the pubic symphysis and abdomen of the mother, which leads to spontaneous delivery of the fetal head
Burns-Marshall technique
- NOT ADVISED due to concern over extension of the fetal neck
Head entrapment with breech
McRoberts
Uterine reflection - GTN, terbutaline, GA
Duhrssen’s incisions - at vaginal delivery: incisions in the cervix at 2, 6 and 10 o’clock
- Can complicated up to 14% of preterm vaginal breech deliveries
At CS: vertical uterine incision extension (J or inverted T)
- With or without tocolysis
Symphysiotomy
Zavanelli manoeuvre and CS
Outcomes for ECV
Factors that can affect success rate
Success rate is ~50%
40% for nulliparous, 60% for multiparous
Race (non-white) Parity Uterine tone Liquor volume Engagement of the breech Use of tocolysis (e.g. 250mcg sc terbutaline 10 mins prior to first attempt) Maternal BMI Type of breech (complete)
Routine use of regional analgesia or neuraxial blockade is not recommended
Complications of ECV
Spontaneous reversion to breech presentation after successful ECV is <5%
Placental abruption
Large fetomaternal haemorrhage
Increased rate of emergency CS (0.5%) I
Operative vaginal delivery rate is increased following successful ECV
Minor complications occur in 4.3%
- Transient CTG abnormalities
- SROM
- Small APH
Labour after ECV is associated with a slightly increased rate of CS and instrumental delivery compared with spontaneous cephalic presentation
ECV contraindications
An absolute reason for CS (e.g. praevia)
Current or recurrent (less than 1 week) APH
Abnormal CTG
Major uterine anomaly
Rupture of membranes
Multiple pregnancy, except after delivery of first twin
Relative contraindications: SGA with abnormal Doppler Proteinuric PET Oligohydramnios Major fetal anomalies Scarred uterus (ECV after 1x CS appears to have no greater risk than unscarred uterus) Unstable lie Restrictive nuchal cord Hyperextension of the head
ECV procedure
Fetal monitoring with USS - every 2-3 mins
Total time spent in the actual manipulation of the fetus should not exceed 5 minutes
Max 3 attempts per session
CTG post attempt (successful or unsuccessful) of >40 minutes
Cord prolapse incidence
More common with:
0.1-0.6% of deliveries complicated by cord prolapse
Perinatal mortality rate of nearly 1%
Half of cases proceeded by obstetric intervention
Premature labour
Non-cephalic presentations
- ~1% of breech presentations
Multiple pregnancies
Risk factors for cord prolapse
Multiparity Low birthweight (<2.5kg) PTL Fetal congenital anomalies Breech presentation Transverse, oblique, unstable lie Second twin Polyhydramnios Unengaged PP Low-lying placenta
ARM with high PP
Vaginal manipulation of the fetus with ruptured membranes
ECV (during procedure)
Internal podalic version
Stabilising IOL
Insertion of intrauterine pressure transducer
Large balloon catheter IOL
Management of umbilical cord prolapse
CS
Elevate presenting part
Digitally
Filling maternal bladder
- 500-750ml of warm saline then clamp catheter
Knee-to-chest position or Trendelenberg (left lateral, pillow under left hip)
Tocolysis
Avoid handling loops of cord to prevent vasospasm
Assisted delivery definitions and incidence
10% of births in NZ /Au
Outlet
- Fetal scalp visible without separating the labia
- Fetal skull has reached the pelvic floor
- Fetal head is at or on the perineum
- Rotation does not exceed 45 degrees
Low
- station +2 or more, but not on the pelvic floor
- Non-rotational - rotation of <45 degrees from the OA position
- Rotational - rotation of >45 degrees including OP
Mid
- Fetal head is no more than 1/5th palpable per abdomen
- Leading point of the skull is above +2 but not above the ischial spines (0, +1)
- Non-rotational or Rotational
High
- Instrumental vaginal birth is not recommend in this situation (except for a second twin)
- Head is 2/5 palpable abdominally and the PP is above the level of the ischial spines
Indications for assisted delivery
FETAL
Suspected fetal compromise
- CTG pathological
- Abnormal FBS result
- Thick meconium
MATERNAL
Delay in the second stage
- No clear demarcation as to the appropriate length of time to wait before doing an instrumental for delayed progress in the second stage
Maternal exhaustion or distress
Medical indications to avoid Valsalva manoeuvre
- E.g. cerebral aneurysm, risk of aortic dissection, proliferative retinopathy, severe HTN, cardiac failure
Contraindications for assisted
Relative contraindications:
- Suspected fetal bleeding disorders
- Suspected fetal predisposition to fracture
Vacuum delivery should not be used for:
- Face presentation
- Gestation <34/40 - 34-36/40 is uncertain and should be used with caution
Ways to reduce the need for instrumental delivery
May reduce with:
- Continuous midwifery support during labour
- Use of upright or lateral positions in the second stage
Newer studies (since 2005) have not found an association between epidural and instrumental delivery
Cautious and appropriate oxytocin use
Up to 2h passive descent if epidural
Insufficient evidence to recommend:
- Routine oxytocin in women with epidural
- Prophylactic manual rotation
Manual rotation
Cochrane 2014 - insufficient evidence
May be used alone or with assisted delivery
Success rates of 76-89% have been reported
Less successful in nulliparous patients, performed before full dilatation or if performed after pushing commenced
If successful increases both SVD and instrumental birth rates
Complication rate appears low
Forceps vs. Ventouse
Advantages over Ventouse - Vaginal is more likely to be achieved - Vaginal birth will occur over a shorter time interval Trend towards fewer cases of: - Cephalohematoma - Fetal retinal haemorrhage - Neonatal jaundice - Shoulder dystocia
Disadvantages over Ventouse
- Higher incidence of OASIS
- Higher incidence of vaginal trauma
- Higher incidence of incontinence / altered continence
No significant difference
- Any neonatal injury
- Low Apgar score (<7) at 5 mins
- Low pH (<7.2) in umbilical artery at birth
When to abandon procedure - assisted delivery
Unable to apply instrument, unable to lock
No progressive descent of fetal head over contractions
Delivery not imminent after 3 contractions when correctly applied instrument used with experienced operator
Pop-offs?
- Two pop offs - discontinue
- Less experienced operators - seek senior support after one pop off
Time?
20 mins from time of application to delivery
Risks for failed assisted
Higher rates of failure have been associated with:
- Maternal BMI >30
- EFW >4kg
- OP positions
- Mid-cavity or when 1/5 of the fetal head is palpable
If high risk of failure, attempt instrumental where immediate recourse to CS is available
ANODE trial
UK RCT placebo vs. IV augmentin within 6h of assisted
- IV antibiotics - fewer suspected or confirmed infections (11% vs. 19%)
- Fewer perineal wound infection, perineal pain, perineal breakdown
Without prophylaxis, up to 16% of women have an infection after operative vaginal birth
Single prophylactic IV augmentin 1.2g
Future births after assisted
After an instrumental in first labour, success rates for SVB in next pregnancy reported between 78-91%
Rigid cups (vs. soft cup):
More likely to achieve birth (9.5% failure rate vs. 14.8% failure rate)
Associated with more scalp injuries (24% vs. 13%)
Key parts of Ventouse technique
flexion point = 6cm from the anterior fontanelle and 3cm from the posterior fontanelle in the midline over the sagittal suture
Suboptimal placement a/w increased risk of neonatal trauma, use of sequential instruments and CS for failed instrumental
600mmHg = 0.8kg/cm
Time max 20 mins, if birth not imminent in 15mins ? switch
max 3 pulls without descent of skull, more pulls OK if head on pelvic floor / perineum
Rapid decompression may –> vessel damage and predispose to subgaleal haemorrhage
Acceptable number depends on whether due to equipment failure, poor application or excessive traction
Up to 3 detachments generally considered acceptable
Indicators of correct forceps placement
If correctly applied, the two blades should lock easily but locking does not have to be maintained throughout, only when pulling
Correct application:
- Sagittal suture in the midline
- Posterior fontanelle should be 1 finger’s breath above the shanks
- Fenestrated blades should admit one fingertip between the heel of the blade and the fetal head
Discontinue forceps if:
Forceps cannot be applied easily
Handles do not approximate easily
Lack of progressive descent with moderate traction
- Consider after 1-2 pulls and minimal descent, if the application is suboptimal, the position has been correctly diagnosed or there is CPD
Birth is not imminent following 3 pulls of correctly applied instrument by an experienced operator
Kiellands / rotational forceps - RANZCOG statement
Reviews consistently finds a place for its use
Adequate station, head engaged (from abdo and vaginal assessment)
Adequate analgesia
Adequate experience or supervision
Rotation attempted only when uterus relaxed
- To reduce the risk of C-spine injury
Low threshold for abandoning if:
- Handles do not easily approximate
- Rotation not easily effected with gentle pressure
- Lack of descent with moderate traction
Keillands vs. CS and ventouse
Kiellands compared to CS
- Small but increased risk of traumatic intracranial haemorrhage and cervical spine injury
- Likely to compare favourably with the added maternal risks of emergency CS in the index and subsequent pregnancies
Vacuum compared to Kiellands (meta-analysis)
- Higher failure rates
- Increased incidence of intracranial and subaponeurotic / subgaleal haemorrhage
Fetal complications of assisted delivery
Facial or scalp lacerations (10%) Cephalohaematoma (1-12%) V>F Subgaleal haemorrhage (1 in 300) Facial nerve palsy, corneal abrasion (rare), F Retinal haemorrhage (17-38%), V Skull fracture (rare) F Intracranial haemorrhage (5-15 per 10,000) Cervical spine injury (rare) Jaundice or hyperbilirubinaemia (5-15%) Fetal death
Maternal complications
Vaginal trauma Episiotomy - Vacuum: 50-60% - Forceps: >90% Significant vulvo-vaginal tear - Vacuum 10% - Forceps 20% OASIS - Vacuum: 1-4% - Forceps: 8-12%
PPH (10-40%)
Urinary tract injury
Damage to pelvic floor and anal sphincter
Urinary or bowel incontinence
Subgaleal haematoma
1 in 300 cases of vacuum delivery
Blood accumulates in the space between the periosteum of the skull and the aponeurosis
No boundaries to contain the blood
Emissary veins are sheared or severed
Potential for massive blood loss (20-40% of blood volume)
Mortality of 12%
Increased risk with:
- Metal cup
- Repeated applications
- Excessive traction
- Prolonged traction (>30 mins)
Recognition
- Inspection and palpation of scalp
- Consider if generalised swelling not limited by sutures
- Elevation and displacement of the earlobes and periorbital oedema
- Baby will be irritable
- Serial HC
- Signs consistent with shock
- Dropping hct and rising lactate
- Neurological dysfunction = late sign
Differentials of subgaleal haematoma
Caput succedaneum - oedematous swelling above the periosteum
- Extends across the suture lines
- Generally benign
Cephalohaematoma
- Collection of blood underneath the periosteum - limited to that specific bone by the periosteal attachments (does not cross suture line)
- Presents as a boggy mass within 12-72h
- reabsorbed within a few weeks
Symptoms of faecal and urinary incontinence after birth
Study just under 4000 women contacted 12y after 1st birth
Symptoms of faecal incontinence
- 10-11% for those with only unassisted births, vacuum or planned CS
- 16% in those with any forceps
Urinary incontinence
- 38% for planned CS
- otherwise ranged from 51-56% (forceps < vacuum)
Sequential use of instruments
Associated with increased risk of trauma to the fetus and mother when compared to either instrument alone
Interpret findings cautiously as increasing use of ventouse as primary instrument may be considered as inevitable consequence
Associated with a significant increase in the risk of:
- Intracranial haemorrhage (RR of >3)
- Seizure
- Facial nerve injury
- Depressed Apgar scores
- Lacerations
- PPH
C-section rates 2015
33% Australia
25.5% NZ
Risks of CS
Common: - Persistent wound and abdominal discomfort - Repeat CS in subsequent pregnancies - Readmission to hospital - Minor cuts to the baby's skin Uncommon: - Haemorrhage - Infection
SERIOUS RISKS Uncommon (<10/1000) - Emergency hysterectomy - Need for further surgery at a later date - Admission to ICU - Increased risk of a tear in the womb in future pregnancies - Stillbirth in future pregnancies - Placenta praevia - Injury to the urinary system
Rare
VTE 4-16 /10,000
Death 1 / 12,000 (very rare)
Evidence for IV antibiotics at CS
Estimated 20-25% of women have an infection following CS without antibiotic prophylaxis
AB prophylaxis reduces the incidence of wound infection, endometritis, serious maternal infection by 60-70%
Skin and vag prep at CS
Cochrane review, 2020 - 13 RCTs
Moderate certainty evidence chlorhexidine (compared to iodine) prior to CS probably slightly more effective at reducing surgical site infections
Not clear what is better for the skin
Cochrane review, 2020 - 21 trials
Vaginal prep with iodine or chlorhex (compared to saline or not cleansing) immediately prior to delivery:
- Reduction in endometritis (7.1% vs. 3.1%) - Large reductions if woman in labour, no difference if PROM
- Reduction in post-op fever and post-op wound infection
Joel Cohen vs. pfannenstiel (Cochrane 2013)
Less EBL Shorter delivery time Less operating time Less fever Reduced post-op analgesic requirements Shorter post-op hospital stay for the mother
Delivery of the placenta at CS
Manual removal of placenta at CS is associated with increased blood loss compared with CCT
MROP vs. CCT, Cochrane 2008
- Increased postpartum endometritis
- Increased blood loss > 1000ml
Other evidence based parts of CS
PO azithromycin stat is >4h SROM, to lower risk of endometritis and wound infection
Bladder flap doesn’t lower risk of bladder injury
Subcut fat closure if >2cm to lower risk of wound haematoma and infection (Cochrane 2004)
Some evidence of PICO in elevated BMI -jury is out
Circumstances that increase the risk of fetal injury at CS:
Skull fracture
Intracranial haemorrhage
Following disimpaction where the head is deep in the pelvis
Brachial plexus injury following difficult delivery of the shoulders in the presence of fetal macrosomia
Cervical spine, spinal cord, vertebral artery injury following delivery of the after coming head of a breech presentation
Caesarean section with the fetal head deep in the pelvis
Increased risk of fetal injury - Skull fracture - Intracranial haemorrhage Increased risk of maternal injury - Tears in the lower uterus - Haemorrhage - Urinary tract injury
Pre-op
- VE by senior
- disimpact head
- consider fetal pillow - reduces chance of lower uterine segment tears (no evidence helps disimpaction)
- Anaesthetist should be prepared for acute tocolysis and PPH
Intra-op
- Elevate head from below
- Tocolysis
- Breech extraction
Prepare for PPH
Compared to first stage CS, second stage CS associated with significantly increased risk of maternal morbidity including:
Tears in relation to the uterine incision Haemorrhage Blood transfusion Bladder trauma Requirement for ICU
Categorisation of CS as per RANZCOG
Category 1 Immediate / urgent threat to the life of a woman or fetus
Category 2 Maternal or fetal compromise but not immediately life threatening
Category 3 Needing early delivery but no maternal or fetal compromise
Category 4 At a time to suit the woman and the CS team, understanding that this can be affected by a number of factors
Timing of elective CS at term
Consider maternal and neonatal factors
CS without prior labour a/w increased risk of neonatal respiratory morbidity (2.1-6.8 fold increase in risk) in term infants, including TTN, surfactant deficiency and pulmonary HTN
Proposed from surfactant deficiency in the absence of the catecholamine surge accompanying labour and from a failure to clear fetal lung fluid in labour
Incidence of NICU transfer 2x that a/w planned vaginal birth
Recommend delivery delayed until 39/40 - decreases risk
10% of women booked for CS at 39/40 will labour prior
- Increased maternal hazard a/w emergency CS
- Resource implications
Caesarean Delivery on Maternal Request
- pros and cons
No RCTs comparing el LSCS to planned vaginal birth
Estimates range from 4-18%
El CS reduces:
- UI
- POP
- Anal incontinence and sphincter defect
El CS a/w markedly lower rates of HIE than other modes of birth
When breastfeeding is initiated, mode of delivery has no effect on the number of mothers still BF at 6/12
Em CS can be more hazardous
- Elective CS 7%
- Emergency CS 16.3%
- Instrumental vaginal birth 12.9%
Caesarean Delivery on Maternal Request
- RANZCOG statement
if after full discussion, the patient maintains a request for CS, the obstetrician may:
- Agree to perform the CS, providing the patient is able to demonstrate an understanding of the risks and benefits OR
- Decline to perform the CS in circumstances where:
- The obstetrician believes there are significant health concerns for the mother or baby with CS, or
- The patient appears to not have an understanding sufficient to enable informed consent to the procedure - AND advise the patient to seek the advice of another obstetrician for a second opinion
Likelihood of successful VBAC and factors favouring success
Varies
60-80%
Previous vaginal delivery (especially previous VBAC) is the single best predictor of successful VBAC (85-90%)
Spontaneous onset of labour
Uncomplicated pregnancy without other risk factors
Factors reducing success
of VBAC
Previous CS for dystocia Induction of labour BMI >30 Coexisting fetal, placental or maternal conditions Fetal macrosomia (>4 kg) Advanced maternal age Short stature 2+ previous CS Risk factors associated with an increased risk of scar rupture Gestational age >41/40 Fetal malpresentation
If BMI >40, chances of unsuccessful VBAC and uterine rupture significant increased (>2x risk)
Pros of VBAC
Greater chance of uncomplicated normal birth in future pregnancies
Less maternal morbidity for index pregnancy and future pregnancies
Patient gratification in achieving vaginal birth if that is desired
Avoid major surgery and multiple CS in future pregnancies
Shorter recovery and hospital stay
Less abdominal pain after birth
cons of VBAC
Emergency CS in 25% of cases
Associated with increased morbidity than ERCS
- 13.2% severe complication rate versus 7%
Blood transfusion or endometritis
- 1% higher compared to ERCS
Scar weakening or rupture in 0.2-0.8% of cases
Increased perinatal loss compared to ERCS at 39/40
- 0.2% of cases vs. 0.1% in ERCS
- Stillbirth after 39/40 (due to longer gestation) > Intrapartum death or NND (related to scar rupture in labour)
0.7 per 1000 risk of infant developing HIE
Pelvic floor trauma
Pros of elective repeat CS
Reduced perinatal mortality and morbidity (especially HIE) related to labour, delivery and scar rupture
Convenience of planned delivery date
Avoid late stillbirth
Reduced maternal risks associated with em CS
Virtually no risk of scar rupture
Avoid trauma to the pelvic floor
Cons of elective repeat CS
Need for ERCS in future pregnancies
Increased risk of neonatal respiratory morbidity - low incidence >39/40
- After 40/40 there is no difference
Associated with lower rates of initiating breast feeding
Risk of PE
- Death from VTE 0.01%
Longer recovery period
Longer and possibly more difficult operation due to scar tissue
Uterine rupture incidence
5-7 times in every 1000 attempts, if happens then 1 in 7 chance of serious adverse outcomes (death or brain injury) for the baby
Previous vaginal birth reduces the risk of uterine scar rupture
Risk of uterine rupture increases with:
Previous classical CS
Previous inverted T or J incisions
Low vertical incision
Induction of labour
- Further increased when prostaglandins are used
Augmentation of labour
Inter-pregnancy interval <18 months or <24 months
Conflicting evidence as to whether single layer compared to double layer uterine closure increases the risk of scar rupture
USS measurement of myometrial thickness has not been demonstrated to be sufficiently predictive, or protective, of uterine rupture to be useful in clinical practice
Contraindications to VBAC
3+ previous C-sections
Uterine rupture during previous labour
Previous classical CS
Other pregnancy complications that require CS
Trial of labour after >1 previous CS
Studies generally show, when compared to 1 prev CS:
- Lower success rates for achieving VBAC (71% vs. 77%)
- Higher rates of uterine rupture or scar dehiscence ( 1.6% vs. 0.7%)
- Greater incidence of major maternal morbidity
RCOG recommend may be considered suitable for planned VBAC:
- Fully informed by consultant Obstetrician
- 2x prev uncomplicated CS
Twin gestation ? VBAC
Uncertainty regarding safety and efficacy
Largest study:
- Successful VBAC rate of 45%
- Scar rupture rate 0.9%
Mid trimester delivery ? VBAC
E.g. fetal abnormality or fetal demise Options: - Hysterotomy - D&C - Medical IOL
Misoprostol use
- Goyal, 2009 - scar rupture rate 0.04% (no uterine scar) vs. 0.28% (with uterine scar)
- Gulec (2013) + Berghella (2009) - scar rupture rate 1.9% with 1x CS, 3.7% with >2x CS
Cochrane pain management for women in labour (2012)
WHAT WORKS
- Epidural
- Combined spinal epidural
- Inhaled analgesia
WHAT MAY WORK
- Immersion in water
- Relaxation - associated with fewer assisted vaginal births
- Acupuncture - fewer assisted vaginal births and CS
- Massage
- Local anaesthetic nerve blocks
- Non-opioid drugs
INSUFFICIENT EVIDENCE
- Hypnosis
- Biofeedback
- Sterile water injection
- Aromatherapy
- TENS
- Parenteral opioids
what is a Dermatome
Localised area of skin which is supplied from a single nerve root of the spinal cord
Right half of the body supplied from nerve roots arising on the right side of the spinal cord, and vice versa
Nipple = T4
Umbilicus = T10
Big toe = L5
Posterior aspects of legs, buttocks and perineum = S1-5
Maternal pain transmission in labour
First stage of labour
- Pain arises from the uterus and cervix
- Visceral or cramping pain
- Muscular contractions and distension of the uterus and cervical dilatation (mechanoreceptors) –> pain signal enters spinal cord from nerve pathways from T10-L1
- Labour pain can be referred to the abdominal wall, lumbosacral region, iliac crests, gluteal areas, thighs
Transition (7-10cm)
- Shift from the late first stage to the second stage
- Greater nociceptive input, as begin to experience somatic pain
Second stage of labour
- Combination of visceral pain and somatic pain from the distension of vaginal and perineal tissues
- Fetus descends –> pressure, stretching and potentially trauma
- transmitted to the spinal cord via the pudendal nerve
Opioids in labour
Double-blind RCT found pethidine provided effective pain relief in only 24% of labouring women
Cochrane:
- Parenteral opioids provide some pain relief in labour, but are associated with adverse effects
- Maternal satisfaction is largely unreported, but appears moderate at best
More research is needed
Pudendal nerve block
Palpate ischial spines at approx a finger’s length into the vagina at 4 and 8 o’clock
Pudendal nerve runs behind the sacrospinous ligament and is located ~1cm antero-medial and postero-medial to the ischial spine
Needle needs to be inserted to about 1cm depth
Onset of effect: 10-20 minutes
- Depends on how close the LA is injected in relation to the nerve
Lidocaine 1% with adrenaline max dose
Maximum recommended dose
7 mg/kg
Max total dose: 500mg
LOCAL ANAESTHETIC TOXICITY
Presentation
systemic effects from LA acting on heart muscle and on neuronal tissue of the CNS
Can take up to 60 minutes after injection to occur, depending on the injection site and agent used
- Numbness of tongue and mouth
- Slurred speech
- Muscle twitching
- Irrational conversation
- Anxiety or feeling of impending doom
- Hypotension
- Convulsions
- Loss of consciousness
- Ventricular fibrillation
- Cardiovascular collapse
Local anaesthetic toxicity management
Stop injecting the LA Call for help Maintain the airway Give 100% O2 IV access, bloods Control seizures - Benzodiazepine Assess cardiovascular status throughout
Give intravenous lipid emulsion if in circulatory arrest
- Continue CPR throughout
- Recovery from LA-induced cardiac arrest may take >1 hr
If no circulatory arrest, can consider giving IV lipid emulsion
Space local anaesthetic deposited
for epidural and spinal
Epidural
Outside the CSF compartment, then needs to diffuse across various tissue barriers before acting on neural tissues
Catheter location between the ligamentum flavum and the dura mater which lines the vertebral canal
Usually sited between L3 and L4 vertebrae
Spinal anaesthetic
Within the CSF compartment (intrathecal)
Punctures both the ligamentum flavum and the dura mater
Must be below L1/L2 as this is where the spinal cord proper usually terminates and fans out into the cauda equina
Risks of epidural
Significant drop in BP 1:50
Insufficient analgesia for labour 1:8
Insufficient analgesia for CS 1:20
Severe headache 1:100
Nerve damage - numb patch on leg or foot, weak leg 1:1000
Effects lasting >6/12 1:13,000
Epidural abscess
Meningitis
Epidural haematoma
Accidental unconsciousness
Severe injury, including being paralysed 1:250,000
Epidural labour implications
The timing (early <4cm vs late) has no effect on the rate of CS or other obstetric outcomes
Does not increase the risk of Caesarean section
Instrumental delivery
- 2018 meta-analysis - no difference in instrumental rate in trials conducted after 2005
Duration of labour
- May decrease the duration of the first stage of labour
- May prolong the second stage of labour to a variable degree
Meta-analysis - Primiparous patients who received epidurals were less likely to require rotational or mid-cavity interventions when pushing was delayed for up to 2h or until they had a strong urge to push, provided there was no evidence of fetal compromise
More likely to need augmentation
Post-dural puncture headache
- cause
- features
- management
CSF may leak out into the surrounding tissues from a punctured dural sac
Volume and pressure of CSF falls if leak of CSF > rate of production –> PDPH
Features:
- Occipito-frontal headache, often radiating to the neck and shoulders
- Pain is often exacerbated by sitting and standing, alleviated by laying flat
- N/v
- Hearing loss / muffled hearing
- Tinnitus
- Vertigo / dizziness
- Symptoms usually occur within 72h
Management:
- Anaesthetic review
- Maintain adequate hydration - oral, IVF
- Caffeinated drinks may help
- Simple analgesia - paracetamol, NSAIDs, weak opioids (but avoid constipation)
- Epidural blood patch - Success 70-90%
Increased GA risks in pregnant population:
Failed intubation (rate 1:300 in obstetrics, 10x more common) - Due to laryngeal oedema, complete dentition, large breast tissue, decreased FRC and increased O2 requirements (more rapid desaturation)
Pulmonary aspiration of gastric contents (rate 1:600)
- Due to increased intra-abdominal pressure from gravid uterus, reduced lower oesophageal sphincter tone
Awareness (1 in 400)
- Due to the avoidance of opiates until after the birth of the baby
list the fetal contributions to initiation of labour
Fetal growth and stretch of myometrium
Fetal-endocrine cascade through Pituitary placental adrenal axis
Increased production of CRH (Corticotropin releasing hormone)
Key mechanisms of labour spontaneous vaginal delivery
Descent Internal rotation Extension Restitution External rotation Delivery of shoulders
routine practices at the time of surgery to reduce the risk of operative complications at lower segment Caesarean section.
Joel-Cohen incision
- Shorter operating times and reduced postoperative febrile morbidity
Antibiotic Prophylaxis (within 60 mins prior of skin incision) - Reduce the risk of postoperative infections - Choose antibiotics effective against endometritis, urinary tract and wound infections, which occur in about 8% of women who have had a CS
Neither the visceral nor the parietal peritoneum should be sutured
- Reduces operating time and the need for postoperative analgesia, and improves maternal satisfaction
When there is a well formed lower uterine segment, blunt rather than sharp extension of the uterine incision should be used
- Reduces blood loss, incidence of postpartum haemorrhage and the need for transfusion at CS.
Vaginal preparation at time of IDC insertion
- Reduces risk of post op endometritis
Chlorhexidine skin preparation and let air dry for at least 60 seconds
- Reduce wound infection rates
CCT of placenta
- Reduces PPH risk
transmission pathways of pain during the first and second stages of labour
First stage of labour Via spinal nerves T10-L1
Second stage via the pudendal nerve S2-4
