Labour Flashcards
Define labour
Physiological process during which the foetus membranes, umbilical cord and placenta are expelled from the uterus
What is a sign pregnancy is about to begin?
‘Show’ - clear mucus like discharge
What helps to maintain the mucus plug during pregnancy?
Progesterone
Name four substances involved in imitation of labour
- progesterone
- oestrogen
- oxytocin
- prostaglandins
What is the function of progesterone in pregnancy?
Keeps the uterus settled and prevents gap junctions forming
What is the function of oestrogen in pregnancy?
Makes the uterus contract and promotes prostaglandin production
Describe the effect of oestrogen on oxytocin
Under the influence of oestrogen number of receptors increases causing the uterus to respond to the pulsatile release from the pituitary
What is the Ferguson Reflex?
Increase in oxytocin due to afferent impulses from the vagina/cervix stretch from the baby’s head causes a positive feedback loop
Describe cervical ripening
Softening of the cervix before labour to help dilate
What substances break down cervical connective tissue?
Oestrogen, relaxin and prostaglandins
What changes happen in cervical ripening?
- reduced collagen
- increased glycosaminoglycans
- increased hyaluronic acid
- reduced aggregation of collagen fibres
What is Bishops score used for?
Predicts how likely a patient is to respond to initiation of labour
Describe bishops score
Dilatation 0,1-2,3-4,5+
Effacement 0-30%, 40-50%, 60-70%, 80-100%
Station -3,-2,-1 or +1/+2
Cervical consistency - firm, med or soft
Cervix position - posterior, mid or anterior
Name the two parts of stage 1
Latent Phase
Active Phase
Describe the stage 1 latent phase
Slow cervical dilatation over several hours which lasts until 4cm dilated.
How does the amniotic sac rupture?
Due to regular painful contractions increasing the pressure
Describe stage 1 active phase
4cm - full dilatation, typically 1cm/hour nulliparous and 2cm/hour multiparous
Contractions become more rhythmic and stronger
Name the two parts of stage 2
Passive - no urge to push
Active - head reaches pelvic floor and involuntary desire to push
What happens in stage 2?
Uterine contractions become expulsive and foetus is pushed through the birth canal
How long should stage 2 take?
Nulliparous - <3 hours
Multiparous - <2 hours
What three factors are considered during labour?
Power
Passage
Passenger
Name two types of contractions
Braxton Hicks Contractions
True contractions
What are Braxton Hicks Contractions?
Tightening of uterine muscles, irregular, mild contractions resolve with change in activity, relatively painless
Describe true contractions
Under the influence of oxytocin contractions are evenly spaced with less and less time between them and get more intense over time
How does pressure in the uterus increase with contractions?
The myometrial fibres do not relax fully following each contraction
How do prostaglandins and oxytocin alter contractions?
Prostaglandins - more calcium is released for AP increasing force
Oxytocin - lowers threshold for AP, increasing frequency
Where is the density of muscle highest in the uterus?
Fundus
Where is the pacemaker in the uterus?
Tubal ostia
How often do contractions occur?
3-4 in 10 minutes range from 10-45 seconds
Name three types of pelvis
Gynaecoid - most suitable
Anthropoid - oval inlet and anteroposterior diameter largest
Android - triangle/heart shaped (afro-caribbean)
Where in the inlet/outlet is the widest diameter?
Inlet - widest transverse
Outlet - widest antero-posteriorly
What analgesia can be given during labour?
Paracetamol TENS Entonox IM opiates e.g. Diamorphine Epidural IV patient controlled Remifentanyl Spinal anaesthesia
What are the cardinal movements?
Changes in position of baby’s head in the pelvis
Name the seven cardinal movements
- Engagement
- Descent
- Flexion
- Internal rotation
- Extension
- External rotation
- Expulsion
At what level does extension occur?
Interoitus - brings the base of the occiput in contact with the symphysis pubis due to force from the uterus and pelvic floor
What is crowning?
Appearance of foetal head at introitus, labia is stretched to full capacity and the largest diameter encircled by the vulval ring causing burning/stinging
Why should cord clamping be delayed?
To allow higher infant haematocrit, Hb, blood volume and BP leading to overall better outcomes
What is stage 3 of labour?
Expulsion of placenta and membranes takes around 10 minutes on average
How long should you wait in stage 3 until surgical management?
1 hour
What are the signs stage 3 is occurring?
- uterus contracts/hardens and rises
- umbilical cord lengthens permanently
- frequently a gush of blood
- placenta and membranes appear at introitus
What is involved in active stage 3?
Syntometrine
Cord clamping
Bladder emptying
Cord Traction
Why is active stage 3 offered to all women?
50% lower risk of post partum haemorrhage
What is syntometrine?
Combination of ergometrine and oxytocin
How is the placenta separated?
Shearing force on the spongy layer of decide basalis. The inelastic placenta reduces SA on placental bed due to sustained contractions
Name two technniques of placenta separation
- Matthew Duncan
- Schultz
What volume of blood loss is normal in pregnancy?
<500ml
How is haemostasis maintained in labour?
- tonic contraction (muscle strangulates vessels)
- thrombosis of torn vessel ends (hypercoaguable state)
- myo-tamponade opposition
What is the puerperium?
Period of recovery and repair - return of tissues to non-pregnant state. Around 6 weeks
Name the discharge that can be experienced in the puerperium
Lochia - blood, mucus and endometrial castings
Rubra - fresh red for 3-4 days
Serosa - brown watery 4-14 days
Alba - yellow 10-20 days
What uterine changes occur in puerperium?
Involution, reduction in weight and height, endometrium regenerates by the end of a week
How long does physiological diuresis last?
2-3 days
