Normal labour Flashcards
Define labour.
Labour is the process in which the fetus, placenta and membranes are expelled via the birth canal.
Normal labour description.
- Spontaneous
- 37-42 weeks gestation
- foetus presenting by the vertex
- Results in a spontaneous vaginal delivery (SVD)
What key physiological changes must occur to allow for expulsion of the foetus?
- Cervix softens
- Myometrial tone changes to allow for coordinated contractions
- Progesterone decreases whilst oxytocin and prostaglandins increase to allow for labour to initiate
Define stage I of labour.
Time from the onset of labor until complete dilation of the cervix has occurred.
Stage I latent phase.
Occurs during onset of labor, ends at 6 cm of cervical dilation. Characterized by mild, infrequent, irregular contractions with gradual change in cervical dilation (< 1 cm per hour).
Stage I active phase.
Occurs after the latent phase at ≥ 6 cm of cervical dilation, ends with complete (∼ 10 cm) cervical dilation. Characterized by an increase in the rate of cervical dilation (1–4 cm per hour).
Anticipated progress of stage I of labour.
0.5 – 1.0 cm per hour.
Definition of stage II of labour.
From full cervical dilatation to the birth of the baby.
How long should the active second stage of labour last?
- Primigravida birth would be expected within two hours of active second stage
- Multigravida birth would be expected within one hour of active second stage
Definition of stage III of labour.
The time from the birth of the baby to the expulsion of the placenta and membranes.
What is prolonged third stage of labour?
If it is not completed within 30 minutes of the birth with active management or within 60 minutes of the birth with physiological management.
What does active management of the 3rd stage involve?
- Early clamping and cutting of the umbilical cord (now routine practice is to allow 2-5 minutes of delayed cord clamping for all women unless contraindicated)
- Use of uterotonic medications
- Delivery of the placenta by controlled cord traction
Which drugs does the active management of the 3rd stage use?
- Syntometrine
- Oxytocin
Progress and monitoring
- Maternal observations
- Abdominal palpation
- Vaginal examination
- Monitoring of liquor
- Auscultation of the fetal heart
- Palpation of uterine muscle contractions
Mechanism of labour
- Descent
- Flexion
- Internal rotation of the head
- Crowning and extension of the head
- Restitution
- Internal rotation of the shoulders
- External rotation of the head
- Lateral flexion
Non pharmacological analgesia.
- breathing exercises
- aromatherapy
- water
- hyponobaby
- TENS machine
Simple analgesia
- paracetamol
- dihydocodeine
- aspirin
Other analgesia
- Entonox - nitrous oxide
- opiates
- epidural
- spinal anaesthesia
Paracetamol
Safe throughout pregnancy; may be used in latent phase of labour for pain relief
Dihydrocodiene
- May be useful in latent phase of labour
- Make sure patient aware of side effects (nausea, constipation, drowsiness)
- Risk of neonatal respiratory depression
Aspirin
Avoid in labour for acute pain relief as it increases bleeding risk
Risks from taking NSAIDs in pregnancy
- premature closure of the foetal ductus arteriosus
- foetal oliguria
- oligohydramnios after 30 weeks gestation
- bleeding in foetus
Entonox
- Patient can self-administer during contractions by inhaling through a mouthpiece attached to the wall
- Quick onset, short half-life
- Usually reserved until in active labour
Opiates
- Can cause nausea and vomiting, drowsiness and respiratory depression in the woman
- Can cause neonatal respiratory depression
- Usually co-prescribe with an antiemetic
- example is Remifentanyl PCA (Patient controlled analgesia)
Antidote to opiate
Naloxone
When is local anaesthetic used?
- injected intradermally before a woman has a large bore IV cannula inserted
- used after delivery to suture an episiotomy or vaginal tear
- pudendal nerve block before an assisted/instrumental vaginal delivery
What drug is normally used for a local anaesthetic?
Lidocaine
Epidural
- Woman and fetus require monitoring when epidural in situ; labour must be managed on a labour ward
- Epidurals are sited by an anaesthetist
- Involves injection of local anaesthetic and opiate medications into the epidural space using a catheter
Epidural advantages
- Effective analgesia during labour
- Can be topped up if need to transfer to theatre for instrumental or caesarean section delivery
- Effective after delivery if need to repair vaginal tears or manual removal of placenta (MROP)
- Best for baby
- Can prevent further raised blood pressure in pre-eclampsia
Epidural disadvantages
- Can fail to provide adequate analgesia (1 in 10 need re-sited)
- Causes hypotension (1 in 50 chance; dose-dependent)
- Reduces woman’s mobility
- Dural puncture (1 in 100 chance)
- Epidural haematoma / abscess (<1 in 10000 chance)
- Risk of respiratory depression (1 in 100 to 1 in 1000 chance)
- Risk of neurological deficits (1 in 10000 to 1 in 40000 chance)
Spinal anaesthesia
- Used for most caesarean sections (elective and emergency)
- Usually a local anaesthetic and opiate medication are injected into the subarachnoid space
- The anaesthetist must check the level of the anaesthetic block is adequate before the operation begins
Spinal anaesthesia advantages
- Gives dense, anaesthetic bilateral block
- Patient can stay awake & protect own airway during operation
- woman can stay awake to meet her baby
Spinal anaesthesia disadvantages
- 2-3% risk of inadequate pain relief - may need other analgesics or may require general anaesthetic
- Shorter duration - can wear off. May be problem if surgery takes longer than expected (>60-90mins)
- Causes hypotension (due to blockade of the sympathetic nerves) similar to epidural and general anaesthetic
- Patient needs urinary catheter
- Risk of dural puncture - post dural puncture headache
- Patient may suffer from pruritus or nausea and vomiting
- Small risk of nerve damage
Dural puncture
- post dural puncture headache (worse on sitting up or standing; can be treated using a epidural blood patch)
When may a general anaesthetic be required for a pregnant woman and what are the risks?
- General anaesthetic (GA) agents may be required for pregnant women for example if an emergency caesarean section is needed and there is not enough time to site a spinal anaesthetic block or if spinal anaesthesia fails
- General anaesthesia can be more difficult in pregnancy due to increased risk of aspiration of stomach contents and more difficult intubation in pregnant women
