Normal labour Flashcards
What do we class to be a term pregnancy
37-42 weeks
How is labour initiated?
Increased production of oestrogen which does 2 things:
- triggers the release of prostaglandins
- promotes the formation of oxytocin receptors (so myometrium is more receptive to oxytocin)
- prostaglandins and oxytocin then help ‘ripen’ cervix
How does the myometrium change towards end of pregnancy?
- Myometrium stretches which increases muscle excitability
- Gap junctions are formed (because of oestrogen) which enable electrochemical signals> synchronised contraction
What are the two main phases of labour? (where should they be at these points)
LATENT from beginning of labour up to 4cm dilation
- painful irregular contractions
- can be managed at home (MOBILISE, hydrated, eating snacks, mobilising, resting, warm baths, massages paracetamol)
ESTABLISHED Dilation of 4cm up to delivery
- Should come in for midwife care
What are the three stages of established labour?
Established labour (more regular contractions)
STAGE 1-cervical dilation
-4cm-10cm
-longest stage
STAGE 2 (prolonged if >4 hours) -Full dilation (10cm) to delivery of baby (0/5 in abdomen)
STAGE 3. Delivery of baby to delivery of placenta (prolonged if 30 mins+)
What two changes does the cervix go through during labour?
Decrease in collagen and an increase in water content causes the cervix to ‘ripen’
- Soften
- Dilation (stretching to 10cm)
- Effacement (flattening against baby’s head)
What is the expected rate of dilation during stage 1 of established labour?
2cm every 4 hours
As well as cervical dilation what else is monitored to track the progress of labour?
-Midwives also monitor the descent of the baby’s head (known as its STATION)
-Positive is below the ischial spines (e.g. +1, +2, +3) and negative is above (-1, -2, -3)
‘positive is good’
What are the further two stages of STAGE 2 of established labour?
How many hours is a prologued second stage?
PASSIVE AND ACTIVE LABOUR
PASSIVE = woman is fully dilated but is not yet having an explosive or involuntary urges to push
ACTIVE = expulsive contractions occur and women get very strong urge to push
<1 hour for multips
<2 hours for nullips
How should active labour be managed?
- Should be slow and controlled - woman shouldn’t necessarily be pushing the whole time - important to have breaks
- This reduces risk of perineal TRAUMA and also harm to baby (blood supply is reduced, there is HYPOXIA when the woman is pushing)
Describe the 2 ways stage 3 of labour can be managed?
PHYSIOLOGICAL
- no drugs (just maternal effort)
- no clamping of drugs (until cord stops pulsating)
- can take up to an hour
ACTIVE
- Uretotonics e.g. SYNTOMETRINE to help the uterus contract back down and stop bleeding
- Deferred clamping and cutting of the cord if possible (>1 min)
- Controlled cord traction (apply counter-pressure just above the pubic bone to guard the uterus + apply gentle downwards traction on the cord)
- 15 mins
Advantages of ACTIVE delivery of placenta?
Disadvantages?
Advantages
- better for higher risk pregnancies/long pregnancy
- reduce risk of PPH
Disadvantages
- can’t used syntrometrine in HTN
- involve N and V for woman
(syntrometrine is more effective than syntocinon but has more side effects)
Summarise and explain the mechanisms of labour and the descent through the birth canal
MECHANISM OF LABOUR
1. ENGAGMENT (when head is within largest part of pelvis)
- DESCENT (contractions and amniotic pressure
- FLEXION
- INTERNAL ROTATION of head (from transverse to occipito-anterior)
- CROWNING
- EXTENSION of neck and delivery of head (when hits pelvic floor)
- EXTERNAL ROTATION/restitution (head to medial thigh 90 degrees)
- note time of head delivery - Delivery of the ANTERIOR shoulder
- Delivery of the POSTERIOR shoulder
How is the mother monitored during labour?
Maternal monitoring in labor
- Contractions (frequency, strength and length)
- Vaginal examinations
- Vaginal loss
- Vital signs (infection, hypertension, or early signs of shock from concealed bleeding)
How is the fetus monitored during labour?
Why do we do it?
Fetal monitoring in labour
LOW RISK
-Intermittent ausculation of the fetal heart
using a Doppler ultrasould or Pinard stethoscope
-every 15 mins 1st stage / 5 mins 2nd stage
HIGH RISK
- Continuous fetal monitoring using a cardiotocograph (CTG)
- Done to identify hypoxia before it is sufficient to lead to damaging acidosis and long-term neurological damage
How many babies rotate to occipto-posterior?
5% will present occipto-posterior
Explain the pain in the 1st stage of labour
Pain in 1st stage labour
- Uterine contractions
- Dilatation of the lower segment of the uterus and cervix
- 4cm and up means 2nd stage of labour
- Visceral pain - colickly, poorly localised
- T10-L1
- Pressure on pelvic structures causes pain with afferents via L2-S1 roots
Explain pain in second stage of labour
Second stage of labour
- Pain of the first stage continues
- Dilatation and pressure on pelvic organs and pelvic floor structures
- Pudendal nerves
- S2, 3, 4 roots
- Somatic pain - sharp, well localised
What are some options for pain management in labour?
PHARMACOLOGICAL
Systemic
-Entonox NO (gas and air) (quick onset/offset, nausea, dizziness)
-Paracetamol
-Opiates with anti emetics (dihydracodiene> diamorphine) can make them feel tingly
Regional
- Pudendal nerve block
- Epidural (best cover, good if HTN)
- Spinal (C section)
- Combined spinal and epidural - (advanced labour, perineal pain and re-siting epidural)
NON-PHARMACOLOGICAL
Massage, water bath, Relaxation and breathing, mobilisation, TENS (not in established labour)
Does epidural have any impact on mode of delivery?
Slightly increased chance of instrumental delivery due to the decreased urge to bear down
What are some contra-indications to epidural?
Absolute contraindications
- Increased risk of bleeding - so this is anyone with a thrombophillia or anyone with HELLP (low platelets)
- Anyone with previous reaction to LA
- Infection (local or systemic)
Relative
- Massive heamorage (will lead to low vascular tone)
- Spinal surgery
What are some effects / risks of epidural?
What effect does it have on labour?
Immediate
- hypotension (activation of autonomic pathway)
- LA toxicity
- Total spinal (large dose meant to be in epidural> goes into spinal> more common with combined)
Delayed
- post dural puncture headache
- heamatoma
- infection
Do epidurals…
prolonged labour?
increase risk of CS?
cause chronic back pain?
increase risk of instrumental delivery?
DOES prolong labour
It DOES NOT increase the risk of CS
NO EVIDENCE of chronic back pain in women who had had them
SLIGHTLY INCREASES RISK OF INSTRUMENTAL DELIVERY
Weak legs 1 hour after an epidural-what do you do?
a) If the same feeling as during epidural-its okay, just needs more time to wear off
b) if worse/different to epidural-?heamatoma pressing on spinal cord> MRI and neurosurgery for evacuation RARE EMERGENCY
Woman with epidural is lying flat in bed complaining of breathlessness , differential?
initial management?
Anaesthetic related
- high block -affecting chest wall
- LA toxicity
Pregnancy related
- aorto caval compression
- PE
- cardiomyopathy
- anaemic (chronic or haemorrhage
Medical
- pneumonia
- anxiety
- anaphylaxis
- MI
Management: stop epidural, A to E assessment and reassess if its still their
Can you use NSAIDS in pregnancy?
Why?
No
- misscarriage and malformation in 1st trimester
- premature closer of ductus arteriosus in 3rd trimester
How long is established/active phase of labour for nulliparous women
12 hours 1st time mum
