Labour Flashcards
What are the 3 stages of labour
1 - start of contractions to full cervical dilation
2 - cervical dilation to birth of baby
3 - birth of baby to delivery of placenta
What are the 3 Ps of labour
Power, passengers, passage
Why are ischial spines important in delivery
2 things:
- station zero is when baby’s head is at ischial spine, can only do instrumental if baby’s head has reached this
- important for delivery PUDENDAL NERVE BLOCK
Why does foetal head rotate on its way down
Pelvic outlet is widest transversely and then AP. Therefore head rotates from transverse to AP on its way down. (this occurs in midpelvis)§
What are the four types of pelvis
Gynaecoid
Android (predisposes to failure of rotation)
Platypelloid (kid prefers occipito posterior)
Anthropoid (predisposes to failure of rotation)
What is the vertex
Usually presenting part
It’s the part in between ant and post fontanelles and where the parietal bones fuse
How do you describe descent
Position of posterior fontanelle in relation to pubic symphysis
Which position has the greatest presenting diameter
mento-vertical - 13cm
What are the actions of progesterone on the uterus
Prevent prostaglandin production
Inhibit gap junction formation
Prevent oxytocine release
PROMOTES QUIESCENT UTERUS
What two molecules are needed for labour
Oxytocin
Prostaglandin
What is the ferguson reflex
Pressure of foetal head on cervix makes maternal pit. secrete more oxytocin which causes contractions and further increases pressure
How is progesterone dethroned at the end of pregnancy
Oestrogen opposes prog actions
chorion starts making PG. - (increase calcium)
CRH conc. (from placenta) increases at the end of term which potentiates action of PG + Ox
Production of cortisol from foetus stimulates conversion of prog to oestrogen
What is the definition of labour
presence of painful contractions which lead to progressive cervical changes
What is the diagnosis of 1st stage
cervix 10cm
What are the 2 phases of 1st stage
latent (effacement of cervix to 3-4 cm dilation w/ contractions)
Active ( 3/4cm –> 10cm dilation)
What are the two phases of 2nd stage
Passive - time between mx cervical dilation and involuntary expulsive contractions (1-2 hours) head is high in pelvis
Acitve - urge to bear down (no longer than 2 hours)
What is a long 3rd stage
should take 5-10 mins
anything more than 60 mins is abnormal
How to gauge engagement
Palpate foetal head in abdomen (if >2/5 then not engaged)
Mechanism of labour
engagement descent flexion of head internal rotation extension restitution external rotation delivery of shoulders and foetal body
What are indications for increased foetal monitoring during labour
Significant meconium Abnormal FHR PV bleeding If they're being augmented Maternal pyrexia
What to look at in CTG
Baseline
variability
acceleration
deceleration
How to read CTG
All normal - reassuring
1 abnormal - suspiscious
2 abnormal - pathological CTG
How long after reaching full dilation (second stage) should baby be delivered?
Baby should be delivered 4 hours after start of stage 2
What is the management of 3rd stage
Active management - controlled cord traction to pull placenta out
Physiological - let mum do it (recommence active if >60 minutes or haemorrhage occurs)
If placenta retained go to theatre for manual removal of placenta under anaesthesia
What is primary arrest
Where woman doesn’t progress into active phase of 1st stage - characterised by cervical dilation of less than 1cm per 2 hours. caused by poor contractions and cephalopelvic disorders
What is secondary arrest
Where progress in active first stage is good but then it stops (cervix doesn’t dilate past 7 cm)
-malposition
malpresentation
- cephalopelvic disorders
Definition of poor progress in 1st stage
dilation of less than 2cm in 4 hours
Should be 1cm every 2 hours
(can be down to any of 3 ps)
Mx of dysfunctional uterine activity
Aim for 4-5 contractions per 10 mins (if it’s less than this)
If not happening do ARM (examine every 2 not 4 hours in this case)
If after 4 hours nothing has changed then give oxytocin (remember to give epidural before this)
On oxytocin need constant foetal monitoring
If no progress on oxy for 4-6 hours ECS§
What are you concerned about in poor progress of 1st stage in multip
malposition and risk of rupture
What suggest cephalopelvic disproportion
foetal head not engaged
slow progress in presence of good contractions
head poorly applied to cervix
haematuria
Mx cephalopelvic disproportion
Can give oxy in primigravida with suspected CPD
NEVER in multip
Which presentaiton can you deliver
Face - should be ok
Brow. - NO
Shoulder - questionable
Who is at higher risk of malpresenation
HIGH PARITY
uterine rupture
Causes of abnormalities of birth canal
Undiagnosed fibroids
Cervical dystocia - cervix effaces but doesn’t dilate cause of surgeries or something
Causes of poor progress of 1st stage
Dysfunctional uterine activity (MOST COMMON)
CPD
Malpresentation
Abnormalities of birth canal
How long should it take to give birth from active second stage
Nullip - 3 hours
Multip - 2 hours
W
When to diagnose delay of second stage
If birth isn’t imminent after
1 hour in multio
2 hours in nullip
Causes of poor progress in second stage
Secondary dysfunctional uterine activity
Android pelvis
Resitant perineum
Persistent OP position
What is a RF for secondary delay
Epidural analgesia
Sometimes associated with maternal dehydration
Mx of secondary delay
In nullip - if no mechanical obstruction can give oxytocin IV
In multip - full obstetrician review to assess whether you want to give oxytocin
NB- by time delay of second stage has been diagnosed you should not be giving oxytocin, should diagnose and correct this at the start of second stage
When is meconium concerning
If it’s bright green or black
if it’s tenacious (thick and clingy)
What to do if pathological CTG
Immediate vaginal exam to exclude cord prolapse and malpresentation
If cervix fully dilated can do instrumental
If not then do foetal blood sampling
If normal carry on for 30-60 mins
If abnormal emergency CS
What are you looking for in foetal blood sampling
Level of acidosis
If less than 7.2 it’s foetal compromise
7.2-7.25 borderline
7.25 normal
Side effects of opiatae analgesia
Vomiting and nausea - give w/ antiemetic
Delayed gastric emptying - interfere with GA
Resp distress in foetus
Can interfere with breastfeeding
Whis is NO not good in long term
Leads to hyperventilation, hypocapnia and potentially foetal hypoxia
What are indications of epidural
High risk of operative delivery maternal hypertension select maternal conditions multiple pregnancy prolonged labour and oxytocin use
Contraindications for epidural
Coagulopathy
sepsis
hypovolaemia
Complications of dural
Dural puncture
Spinal haematoma
Leakage of CSF into subarachnoid space - spinal headache
Complete spinal anaesthesia - spinal headache
Bladder dysfunction - CATHETERISE
Hypotension - give IV fluids and vasopressors
When is rupture most likely to happen
In late first stage when being augmented or induced
Contraindications for VBAC
Relative (no more than 2):
Need for induction
2 or more c sections
Hx of CPD
Absolute contraindications:
Classical caesarean
pervious uterine rupture
When to induce in PROM
> 37 induce roughly 24 hours after PROM
<34 need another reason to induce
34-37 case by case basis
What are the absolute contraindications for IOL
Placenta praevia
Foetal compromise
what is the bishop score
For induction
Looks at cervical changes (high score = more favourable cervix)
How to induce labour
PGE2 - most common (first line)
ARM - only possible if cervix is beginning to dilate and efface. Don’t do if presenting part is mobile and high
IV syntocinon - offer if 2 hours after membranes rupture labour hasn’t started (to increase til 3-4 contractions per 10 mins)
Special circumstances:
Mifepristone and misoprostol (often used following intrauterine foetal death
Cervical sweep to break membrane and release prostaglandin. offered prior to formal measures especially from 40 weeks
Complications of induction
increased risk of uterine atony
foetal compromise due to uterine hyperstiulation as s/e of prostaglandin
Risk of ARM
cord prolapse
Monitoring during normal labour
1st stage - every 15 mins foetal HR every 30 mins frequency of contractions every hour maternal HR every 4 hours - vaginal examination
2nd stage -
every 5 mins foetal HR
every 30 mins frequency of contractions
every hour - vaginal exam
counselling for VBAV
VBAC -
positive predictors: hx of successful VBAC, normal size baby, reduce need for C section in further pregnancies
Risks of VBAC - uterine rupture 1in 200, success ratea 70-75%
Elective repeat c-section-
risk of another CS, risk of placenta praevia/accreta in future pregnancies
avoids risk of future emergency C section and uterine rupture
