what is the definition of labour?
process by which foetus, placenta and membranes are expelled from the uterus through the birth canal
between how many weeks gestation does labour usually occur?
37 to 42
how is the diagnosis of labour made? (2 marks)
- 1. painful uterine contractions
- 2. dilation and effacement of cervix
describe the stages of labour
- 1. first stage: cervix opens to full dilation to allow head to pass through
- 2. second stage: from full dilation to delivery of fetus
- 3. third stage: from delivery of fetus to delivery of placenta
what are the early signs of labour?
- 1. lightening: fundus (top) of uterus drops down, mum feels like she can breathe better
- 2. frequency of micturition
- 3. heavy sensation or discomfort in the upper thighs and pelvic area
- 4. lower backache - as baby drops down, also ligaments are softer and more stretchy so the baby can move down.
- 5. false pains, increase in braxton hicks (contractions, not painful and shouldn't carry on for more than 32-24 weeks
- 6. ripening of cervix: cells get softer, more fluid around there (cf to normal: firm like tip of nose)
- 7. nesting instinct! to decorate room, spurt of energy
- 8. feeling generally unwell
what are 3+1 true signs of labour?
- 1. painful RHTYMIC uterine contractions
- 2. dilatation of cervix
- 3. show - mucus plug, blood stained in os of cervix
- 4. ROM - but this may happen before or after labour has started
what are the 3 mechanical factors that determine progress during labour?
- powers: how much FORCE to expel fetes
- passage: dimensions of pelvis and resistance of soft tissues
- passenger: diameters of fetal head
how do you assess progress in labour? 4 parts
- 1. frequency of uterine contractions
- 2. abdominal palpation
- 3. vaginal examination
- a) cervix: CDE P - consistency, dilation, effacement, position
- b) membranes: present of ROM? colour of liquor (meconium stained?)
- c) position: which was is baby facing?
- d) station (level of descent): descent of head in relation to ischial spines: how many cm -/+
- 4. partogram: dilation of cervix & descent of head
what is effacement? and what triggers it?
- pulling up of cervix is effacement
- uttering contractions pulls cervix up and causes dilation
- pressure of head also helps effacement
name 2 risk factors for poor uterine activity
- 1. nulliparous women
- 2. induced labour
what are the 3 planes of pelvic inlet and difference in AP and transverse diameters in each?
- 1. inlet: transverse (13) > AP (11)
- 2. mid-cavity: almost round as transverse = AP almost
- 3. outlet (look between legs): AP > transverse
what are the different types of cephalic head presentations and how do they affect delivery?
- 1. vertex presentation: maximal flexion of head on neck. presenting diameter only 9.5
- 2. brow presentation: extension of 90 degrees, diameter 13cm!
- 3. face presentation: further extension of 30 degrees. face looking parallel and away from body
what is the position?
degree of rotation of head on the neck.
what is the best head position at pelvic INLET?
occipital transverse (ie the saggital suture is transverse and head is oblong)
what is the best head position at pelvic OUTLET?
occipital anterior as the AP>transverse.
what manoeuvre does the head have to do between the pelvic inlet and outlet?
rotate 90 degrees to go from OT to OA
what are the 6 steps / movements of head during delivery?
- 1. engagement: inlet OT (as transverse > AP)
- 2. descent (into mid cavity) and flexion (as cervix dilates)
- 3. rotation in mid cavity: so from OT to OA to get through pelvic outlet where AP>transverse
- 4. further descent: perineum distends
- 5. extension and delivery: so mouth facing mums anus
- 6. restitution: head rotates 90 to same position which entered inlet so can delivery shoulders
what role does prostaglandins have in labour?
- 1. reducing cervical resistance
- 2. increasing release of oxytocin from post pit gland
what leads to effacement and dilation of cervix?
painful regular contractions
what is effacement? what is it accompanied by?
- when the normally TUBULAR cervix is DRAWN UP into the lower segment until it is FLAT
- see SHOW - pink white mucus plug from cervix
what are the 2 phases of the first stage of labour?
- latent: cervix dilates slowly for first 3 cm and may take hours
- active: 1cm/h in nulliparous, 2 in multip. first stage shouldn't last longer than 16h
what are the 2 phases of the second stage of labour?
- passive: full dilatation till head reaches pelvic floor and get desire to PUSH
- active: mother is pushing with contractions. if takes >1h then spontaneous delivery is less likely
what is normal blood loss after delivery of fetes and delivery of placenta?
what helps reduce blood loss?
uterine muscle fibres contract to compress blood vessels formerly supplying the placenta
what 6 aspects of physical health are managed in labour?
- 1. observations
- 2. mobility and delivery positions
- 3. hydration
- 4. stomach and food
- 5. pyrexia in labour
- 6. urinary tract
what can happen to the BP with epidural anaesthesia? and how treat?
- iv fluids and ephedrine
why should pregnant women not lie on their back? what is the name of this and how to prevent?
- gravid uterus compress the main blood vessels, reducing CO cause hyoptension and fetal distress.
- called aortocaval compression
- prevent: maintain at least 15 degree of left lateral tilt
what is pyrexia in labour defined as and associated with?
- it is > 37.5
- associated with increased risk of neonatal illness and not always as a result of chorioamnionitis
what is pyrexia in labour more common with?
- epidural anaesthesia
- prolonged labour
how is pyrexia managed?
- 1. culture: vagina, urine, blood
- 2. anti-pyretics
- 3. iv abx if fever reaches 38 or other RF for sepsis
what is a RF for urine retention in labour? and why
- removes bladder sensation
- so woman must be encouraged to micturate frequently in labour
- if epidural - catheterise
what are the 2 main things measured by the partogram?
- 1. progress in dilation of cervix
- 2. descent of head
what is the commonest cause of slow progress in labour?
inefficient uterine action
why does anxiety cause problems in contractions?
anxiety releases adrenaline which reduces contractions
if there is persistnely slow progress in labour, what 2 interventions are done
- 1st: ARM (artificial rupture of membranes) = amniotomy
- 2nd: oxytocin
what can happen with the use of too much oxytocin or as a SE of PG in induction or in placental abruption? what are signs of this? what is Rx?
- hyperactive uterine action
- signs: FHR abnormal as placental blood flow is diminished and labour may be very rapid
- Rx: if no evidence of abruption then give tocolytic eg salbutamol which suppresses premature labour
- CS often indicated due to fetal distress
what is slow progress in the nulliparous woman usually due to?
- think of one of the PPP. in this it is the powers
- inefficient uterine action, even if contractions are frequent or feel strong
what is augmentation? and how is it done?
- augmentation is strengthening POWERS artificially
- do ARM and give oxytocin
- must use electronic fetal monitoring
If full dilatation doesn't happen within 12-16h of augmentation, what needs to be done?
- diagnosis reconsidered
- c section
if descent of the head is poor ie passive 2nd stage, what should be done?
- oxytocin infusion started
- pushing delayed by up to 2h
if active 2nd stage lasts > 1h what bad things can happen?
- spontaneous delivery less likely due to maternal exhaustion
- fetal hypoxia and maternal trauma
if the head is not DESCENDING but is DISTENDING the perineum, what can be done?
if the head is not DESCENDING or DISTENDING the perineum, what can be done?
need traction to fetal head: ventouse or forceps
what is the most likely cause of slow progress in 1st stage of labour in multiparous, why different to nulli?
- cause: fetal head - attitude or position or size
- not due to uterus problem or pelvic capacity (is not powers or passage, so its the passenger thats the problem!)
which uterus is more prone to rupture, multi or nulliparous? and how does this affect management?
multiparous so augmentation of labour with oxytocin must be preceded by careful exclusion of malpresentation
how can the fetus contribute to poor progress in labour? (passenger)
- disorder of rotation and varying degrees of extension
- remember OA vertex is best and delivery is by extension
if delivery is face to pubis ie OP, how will it be completed?
by flexion rather than extension over the perineum
if head is OP and prolonged active stage what can be done to help?
- instrumental delivery - rotate to OA position using ventouse or manual rotation
- kieland's forceps are best, but need particular expertise
what is to be done if the head is in OT position in 2nd stage?
rotation with traction in order to deliver: use ventouse
how do you get brow presentation? and why bad?
- extension of fetal head on the neck
- bad as large 13cm diameter that wont deliver vaginally
what can be palpated vaginally in brow presentation?
- anterior fontalles
- supraorbital ridge
what is treatment for brow presentation?
if there is complete extension of the head in delivery what is the presentation? and what is palpable vaginally?
- face presentation
- feel eyes, nose mouth vaginally
can face presentations delivery vaginally?
- yes as diameter is 9.5cm, as long as chin is anterior
- and delivery is completed by flexion over perineum
if chin is posterior, what needs to be done and why?
- c section
- as extension of head over perineum is impossible as it is already maximally extended
what else can rarely obstruct delivery - due to the passenger ie fetes
fetal abnormality eg hydrocephalus
how is cephalo-pelvic disproportion diagnosed? remember 3 things
- 1. inability to delivery a particular fetes
- 2. despite presence of adequate uterine activity
- 3. and absence of malposition or malpresentation
what 3 RF make CP disproportion more likely?
- 1. large baby
- 2. very short women
- 3. head in nulliparous woman remains high at term
go through in summary the problems with PPP causing failure to progress in labour
- POWERS: inefficient uterine action
- PASSAGE: cephalo-pelvic disproportion, role of cervix
- PASSENGER: fetal size, disorder of rotation eg OT or OP, disorder of flexion (attitude) eg brow
what % of cases of CP are due to solely intrapartum problems?
what are the 5 main causes of fetal death or damage during labour?
- 1. hypoxia - distress
- 2. infection or inflammation - GBS
- 3. meconium aspiration: chemical pneumonitis
- 4. trauma due to intervention eg forcepts (rarely spont)
- 5. blood loss
what is the definition of fetal distress?
hypoxia that might result in fetal damage or death if not reversed or fetes delivered urgently
which test and result signifies fetal hypoxia?
- pH < 7.20 in fetal scalp (capillary) blood
- but only below 7 that neuro damage is more common
what causes fetal hypoxia?
1. contractions temporarily reduce placental perfusion and compress umb cord: so longer labours and those with >1h pushing more likely to hypoxia
what can cause ACUTE hypoxia in labour? (think of uterus, mum, drugs, connections)
- placental abruption
- hypertonic uterine states
- use of oxytocin
- prolapse of umbilical cord
- maternal hypotension
what are intrapartum RF for fetal hypoxia?
- 1. long labour
- 2. meconium
- 3. use of epidurals, oxytocin
what are antepartum RF for fetal hypoxia?
- 1. high risk pregnancy
- 2. IUGR fetus
if have RF for fetal hypoxia, what needs to be done?
monitor with CTG: cardiotocography
name 5 ways of detecting fetal distress
- 1. colour of liquor: meconium
- 2. FHR auscultation (pinards steth)
- 3. CTG
- 4. fetal ECG
- 5. fetal blood scalp sampling
what is meconium?
bowel contents of fetes that stains the amniotic fluid
which babies is meconium rare in and which common
- rare: preterm
- common: after 42 weeks
when is meconium a problem, and what is the risk?
- undiluted meconium,
- risk of perinatal mortality up by x4
what is meconium an indication for?
caution - ie do CTG surveillance
what are the dangers associated with meconium ?
- 1. aspiration causing meconium aspiration syndrome
- 2. hypoxia more likely
how often is FHR listened to? using what?
- every 15mins in 1st stage
- every 5 mins in 2nd stage
- pinard's stethescope
- or hand help doppler for 60 s after a contraction
what are the features that need to be noted from a CTG? (remember pneumonic)
- DR C BRAVADO
- DR: determine risk (eg comorbidity, prev preg)
- Contractions: x/10 (timing and frequency, remember CTG cannot indicate strength)
- Baseline Rate: 110-160bpm
- Variability of heart rate: should be > 5bpm. if reduced: fetes sleep or maternal use of opiates
- Acceleration: increase in baseline of >15bpm for >15seconds with movements or contractions are REASSURING
- Deceleration: decrease in baseline of >15bpm for >15seconds.
- time with contractions, early = rare and benign; late = pathological and indicate hypoxia; if variable ie vary in timing and in pattern - commonest and occur with cord compression.
- Overall assessment
what are fetal tachycardias associated with?
fever, fetal infection, hypoxia
when is variability in FHR allowed to be reduced? up to how long?
what does prolonged reduction in variability indicate?
what do accelerations on CTG indicate
access of FHR with movements or contractions are REASSURING
what are early decelerations?
- synchronous with a contraction as a normal response to head compression and therefore are usually benign
- ie when get contraction, head may be compressed and FHR goes down early. its ok
what are variable decelerations? what do they reflect classically?
- they vary in timing
- reflect cord compression which can cause hypoxia
what are late decelerations? what suggests?
- persist AFTER the contraction is completed
- suggestive of hypoxia
how is fetal scalp blood sampled?
- amnioscope = metal tube inserted vaginally through cervix, to scalp
- collect blood in microbe and test pH
- if pH > 7.20 then do fastest way of delivery of baby
what are the 2 transducers used in CTG and where place?
- 1. abdominal pressure transdurcer: uterine contractions
- 2. doppler for fetal heart rate
what are 4 levels of screening or tests for fetal distress?
- 1. FHR auscultation. if abnormal or meconium or long, high risk labour…
- 2. CTG. if bradycardia deliver. other abnormalities correct if fails..
- 3. FBS. if ban ie pH <7.20
- 4. delivery by quickest route
what is the management of fetal distress?
- 1. left lateral position: avoid aortocaval compression
- 2. oxygen and iv fluids
- 3. stop oxytocin infusion
- 4. start tocolytics
- 5. vaginal examination to exclude cord prolapse
- 6. fetal blood sampling and delivery if pH < 7.20. if pH > 7.20 but abnormal FHR pattern continues or gets worse then 2nd scalp sample needed
- 7. if fetal scalp impose or bradycardia then delivery quickly
who are high risk for GBS infection?
- maternal fever
- prolonged ROM
when is meconium aspiration more common?
when there is fetal hypoxia
when meconium is present at delivery what should be done to prevent aspiration?
it is sucked out form the babys airways before the body is delivered to prevent the first gasp from aspirating it into the lungs
what are the causes of fetal trauma in labour?
- 1. instruments
- 2. breech delivery
- 3. uncontrolled vaginal delivery with rapid decompression of head
- 4. shoulder dystocia
what are 3 causes of fetal blood loss?
- 1. vasa praevia
- 2. feto-maternal haemorrhage
- 3. placental abruption
what are the 4 main categories of pain relief available in labour?
- 1. non medical
- 2. inhalational
- 3. opiates
- 4. anaesthetic: spinal, epidural, pudendal nerve block
what are the types of non medical pain relief in labour?
- 1. presence of birth attendant, partner
- 2. maintain mobility
- 3. back rubbing
- 4. TENS: transcutaneous electrical nerve stimulation good in early labour
- 5. immersion in water at body temperature
what are the inhalational agents used in analgesia? onset, strength and SE
- entonox: nitrous oxide and oxygen
- rapid onset
- mild strength
- SE: light headed, nausea
which 2 opiates are used in labour? and how administered?
- meptid: meptizanol
- given im
what are 4 SE/problems with opiates in labour?
- 1. analgesic effect is small
- 2. patients become sedated, confused or feel out of control
- 3. anti-emetics needed usually
- 4. respiratory depression in newborn - need naloxone reversal
what is spinal anaesthesia? and effect? and when used?
- local anaesthetic injected THROUGH dura mater into CSF
- rapidly produces short lasting but effective analgesia
- used: C section (if epidural not inset) or mid cavity instrumental vaginal delivery
what are main complications of spinal anaesthesia?
- total spinal analgesia - very rare
what is pudendal nerve block? what is it good for?
- LA injected bilaterally around pudendal nerve where is passes by the ischial spine
- good for: low cavity instrumental vaginal deliveries
what is the difference between spinal and epidural anaesthesia?
- spinal: LA injected into CSF
- epidural: LA via an epidural catheter into epidural space between L3 and L4
- LA is either infused continuously or used to top up.
what kind of anaesthesia do u get with epidural?
- complete sensory (except pressure)
- partial motor blockade from upper abdomen downwards is the norm
- suitable for both entire labour and obstetric procedures
what are the advantages of epidural anaesthesia? include medical uses
- 1. pain-free
- 2. reduce BP in HTN if labour is long
- 3. abolish premature urge to push
- 4. analgesia for instrumental or CS
what are the disadvantages of epidural anaesthesia?
- 1. more supervision needed to check BP and pulse regularly and 2nd stage needs modification
- 2. bedbound and pressure sores
- 3. reduced bladder sensation so urinary retention
- 4. maternal fever
- 5. more instrumental delivery esp if 2nd stage is not modified
- 6. transient hypotension: minimised if iv fluid given first
- 7. transient fetal bradycardias
what are major complications of epidural anaesthesia?
- 1. spinal tap: puncture dura and cause leakage of CSF - severe headache, worse when sit up, better on lying down (low ICP headache)
- 2. iv injection produces convulsions or cardiac arrest
- 3. LA into CSF, going up spinal cord - total spinal analgesia and respiratory paralysis
what are the contraindications to epidural analgesia?
- 1. sepsis
- 2. coagulopathy
- 3. active neurological disease
- 4. spinal abnormalities
- 5. hypovolaemia
if a lady has epidural, when should she push? as she wont get urge
push 3 times for 10s DURING each contraction
what are 3 indications/situations for episiotomy?
- 1. fetal distress
- 2. head not passing over perineum despite maternal effort
- 3. large tear is likely
how is episiotomy done?
- 1. perineum infiltrated with LA
- 2. 3-5cm cut made with scissors from centre of fourchette to mothers right side of the perineum
why are mums asked to pant slowly?
enable controlled and slow delivery of head and reduce perineal damage
in the 2nd stage of delivery, when is instrumentation required?
if delivery is not happening after 1 hour of pushing
what is retained placenta defined as?
3rd stage longer than 30 minutes
if you have partial separation of the placenta (3rd stage) then what can happen, why can it go undetected and what is Rx?
- blood loss into uterus
- without external signs
- Rx: oxytocin infusion. inject 10units into cod
how are 1st and 2nd degree perineal tears repaired?
sutured under LA
how are 3rd, 4th degree tears repaired?
- under epidural or spinal
- operating theatre
- need abx and laxatives and analgesia
what does the success of induction of labour (IOL) depend on? what is the score called?
- favourability of cervix:
- 1. consistency
- 2. degree of effacement or early dilatation
- 3. how low in the pelvis the head is (station)
- 4. cervical position - anterior or posterior within the vagina
- Bishop's score. lower the score, less favourable cervix
what are 3 ways of IOL?
- 1. induction with PGE2: propess
- 2. induction with amniotomy +/- oxytocin
- 3. natural induction: cervical sweeping: pass finger through the cervix and stripping between the membranes and the lower segment of the uterus
what are the fetal indications for IOL?
- 1. prolonged pregnancy
- 2. suspected IUGR
- 3. antepartum haemorrhage
- 4. poor obs hx
- 5. prelabour term ROM
what are the materno-fetal indications for IOL?
- both mum and fetes should benefit
- maternal disease eg diabetes, HTN
what are the maternal indications for IOL?
- social reasons
- in utero death
what are absolute contraindications to IOL?
- 1. acute fetal compromise
- 2. abnormal lie
- 3. placenta praevia
- 4. pelvic obstruction eg pelvic mass or deformity causing cephalo-pelvic disproportion
what are relative CI to IOL?
- 1. more than one CS
- 2. prematurity
what should a woman be warned of when consenting for IOL?
increases time spent in EARLY LABOUR
what else needs to be done with IOL?
monitoring - CTG esp as oxytocin given
what are complications of IOL?
- 1. labour may fail to start or be slow due to inefficient uterine activity
- 2. higher risk of instrumental delivery or CS
- 3. overactivity of uterus - hyperstimulation rare but can cause fetal distress and uterine rupture
- 4. umbilical cord prolapse at amniotomy
- 5. post partum haemorrhage
- 6. infection: intra and post partum
- 7. iatrogenic prematurity by accident ie incorrect dates or design
what are contraindications to vaginal delivery after one CS?
- 1. the usual absolute indications for CS
- 2. vertical uterine scar
- 3. multiple previous CS (in UK after 2 CS hardly ever do vague)
what % of women will succeed in vaginal delivery after having had one CS?
if a lady has had many CS then wants vaginal delivery, what is a particular risk to the mother?
placenta accrete: placenta is so deep that it cannot separate from uterus
what is placenta accreta? and what are 3 forms?
- accrete: deep attachment of the placenta through the endometrium and into the myometrium
- increta: placenta further into myometrium
- pancreta: placenta penetrates the entire myometrium to the uterine serosa -through the entire uterine wall and may even attach to rectum or bladder!
during birth, when do you suspect placenta accrete?
if placenta hasn't been delivered within 30 mins of birth
what are RF for placenta accrete?
- placenta praevia
- prev uterine surgery: scar tissue
what is the risk of placenta accrete to the mother?
bleeding especially if vaginal delivery
what is the safest treatment if placenta accrete is diagnosed before birth (MRI)?
planned CS and abdominal hysterectomy
what are the risks to the fetes of vaginal delivery after previous CS?
uterine rupture especially if labour is induced (so don't induce in previous CS as hard contractions may cause rupture)
what are 3 factors that can cause uterine rupture after previous CS?
- 1. induction esp with PGs
- 2. augmentation
- 3. prolonged labour
how does uterine scar rupture present?
- fetal distress
- scar pain
- cessation of contractions
- vaginal bleeding
- maternal collapse
what is the treatment if uterine rupture is suspected?
immediate laparotomy and CS
what is hindwater ROM?
liquor definitely leaking but membranes remain present in front of the fettle head
what are the risks of prelabour term ROM?
- 1. cord prolapse: usually if transverse lie or breech presentation
- 2. neonatal infection: increased by vaginal examination, presence of GBS and increased duration or ROM
how is prelabour term ROM confirmed?
identification of liquor
what is the management of prelabour term ROM?
- 1. check lie and presentation
- 2. AVOID VE - but may need to if risk of cord prolapse (if abnormal lie or fettle distress) and do in sterile manner
- 3. vaginal swab: screen for infection
- 4. fetal auscultation or CTG
- 5. await spontaneous onset of labour or induce labour
what is a main advantage of IOL instead of waiting for spont labour after prelabour term ROM?
lower chance of maternal infection
if there was is prelabour term ROM, what would warrant immediate induction?
- evidence of infection
if you are waiting for spontaneous labour after prelabour term ROM, and 18 hours has gone and nothing has happened, what should you do?
- give antibiotics (unless swabs confirmed no GBS)
- consider induction