Normal Labour Flashcards
When should labour usually occur?
37-42 weeks gestation
What factors lead to the onset of labour (maternal, physical, foetal)?
MATERNAL: - Rise in oestrogen/prostaglandins - Formation of oxytocin receptors PHYSICAL: - Stretching of uterus - Pressure of presenting part on cervix FETAL: - Fetal pituitary/adrenals
THE PASSAGE - How does the babys head normally descend through the pelvis?
- Head enters the pelvis transversely (diameter 13cm)
- Descends in this position through the mid cavity (round)
- Internally rotates when it hits the pelvic floor
- Exits the pelvis in occipito-anterior through AP (diameter 12.5cm)
THE PASSENGER - Which bony landmarks can be used to assess the head position?
- Posterior fontanelle
- Sagittal suture
- Anterior fontanelle (bregma)
THE POWERS - Once labour is established, how often does the uterus contract?
Every 2-3 minutes, for 45-60 seconds
THE PASSAGE - What does ‘station’ refer to?
The level of descend, in relation the ischial spines (-2 - +2)
THE PASSENGER - What position should the head be in?
Vertex presentation (maximal flexion)
What is the first stage of labour and its subdivisions?
The onset of labour to full dilatation (10cm) of the cervix:
- Latent
- Active
What happens in the latent phase of labour?
- Painful, irregular contractions
- Softening and effacement of the cervix
- Cervical dilatation up to 4cm
What happens in the active phase of labour?
- Painful, regular contractions
- Cervical dilatation up to 10cm
How long does the first stage of labour take?
Primigravida - 12 hours
Multiparous - 7.5 hours
What is the second stage of labour?
Full dilatation to delivery of baby:
- Passive (2hrs): until head reaches pelvic floor
- Active (1hr): push!!!
What is the third stage of labour and how long does it take?
Delivery of baby to delivery of placenta and membranes (15 mins)
This is often managed actively by giving an IM injection of oxytocin following birth, then using controlled cord traction and uterus guarding
How is labour initially managed?
- History/risk assessment
- Contractions (frequency, duration, onset)
- Membranes (ruptured or intact?)
- Maternal obs/urinalysis
- Abdo palpation
- Fetal wellbeing/movements/ausculation
- PV to diagnose onset
What is the Bishop score?
A score to predict whether induction of labour will be required
- Dilatation of cervix
- Length of cervix
- Cervical position
- Cervical consistency
- Head station
A score above 8 means that a normal vaginal delivery should be enough
What is DR C BRAVADO?
This is the acronym to help remember what to look at when monitoring CTG
DR - Define risk C - Contractions (every 2-3min) BRa - Baseline rate (100-160bpm) V - Variability (10-25bpm) A - Accelerations (2 every 15min) D - Decelerations (none) O - Overall impression (reassuring/suspicious/pathological)
When should foetal monitoring occur during labour?
For a minute after a contraction:
Every 15 min in first stage
Every 5 min in second stage
What analgesia can be used in pregnancy?
Non-pharmocological: - Positioning - Water birth - Tens machine - Acupuncture Pharmacological: - Paracetamol - Entonox (NO2 gas and air) - Diamorphine + anti-emetic - Epidural
What is the normal mechanism of labour?
Descent - flexion - internal rotation - crowning - extension - restitution - internal rotation of shoulders - expulsion
What is moulding?
Compression of the head and overlap of sutures - this is a normal foetal adaptation due to the small diameter of the maternal pelvis. It should go back to normal after 24 hours.
Following birth the placenta should be inspected - what should it have to be complete?
3 vessels
2 membranes
What is 1st degree perineal trauma?
Skin around the fourchette (no repair needed)
What is 2nd degree trauma/episiotomy?
Skin plus vaginal wall and perineal muscles
What is 3rd degree trauma?
Skin plus vaginal wall and perineal muscles, and anal sphincter
What is 4th degree trauma?
Skin, vaginal wall, perineal muscles, anal sphincter and rectal tissue
Why shouldn’t pregnant women lie flat?
AORTOCAVAL COMPRESSION - The gravid uterus compresses their blood vessels, reducing cardiac output and causing hypotension, and often foetal distress
What is the partogram?
A chart used to record progress in dilatation of the cervix and descent of the head, in order to monitor the progress of labour
How can foetal wellbeing be monitored?
- CTG
- Fetal scalp blood sampling (pH < 7.2 indicates hypoxia)
- Meconium colouring
- FHR auscultation with Pinard’s stethoscope or Doppler
