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4th Year GOSH > Normal Labour > Flashcards

Normal Labour Flashcards

1
Q

What are the mechanical factors of labour?

A

Power - degree of force expelling the foetus
Passage - dimensions of pelvis and resistance of soft tissues
Passenger - diameters of foetal head

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2
Q

Describe power?

A
  • Uterus contracts for 45-60 secs every 2-3 minutes –> this pulls cervix up (effacement) and causes dilatation, aided by pressure from the head as the uterus pushes head down into pelvis.
  • Poor uterine activity common in nulliparous women/induced labour, rare in multiparous women.
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3
Q

What are the diameters at different parts of the ‘passage’?

A

Inlet

  • Transverse = 13cm
  • AP = 11cm

Mid-cavity
- Both = 11cm

Outlet

  • Transverse = 11cm
  • AP = 12.5cm
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4
Q

Relevance of ischial spines?

A

Palpable vaginally - landmarks to assess descent.

Station 0 = at level
Station +2 = 2cm below spines
Station -2 = 2cm above spines

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5
Q

Soft tissues in the passage?

A

o Cervical dilatation is needed for delivery

o Soft tissues of perineum and vagina need to be overcome in second stage à sometimes tear or epistiotomy to allow head to deliver

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6
Q

What is attitude? (passenger)

A

o Degree of flexion on head and neck

  • Ideal = maximal flexion, keeping head bowed (vertex presentation – presenting diameter = 9.5cm from anterior fontanelle to below occiput)
  • Small degree of extension results in larger diameter –> more difficult delivery
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7
Q

What is position? (passenger)

A

o Degree of rotation of the head on the neck

  • Sagittal suture is transverse –> oblong head will fit pelvic inlet best
  • At outlet, must be vertical for head to fit –> head must rotate 90 during labour
  • Usually delivered occipito-anterior (OA) – 5% OP, more difficult. Occipito-transverse –> cannot be delivered without assistance.
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8
Q

What is the first stage of labour?

A
  • From diagnosis of labour –> cervix dilated by 10cm
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9
Q

What are the two periods of first stage of labour?

A
  • Latent phase = a period of time, not necessarily continuous, when there are painful contractions, and some cervical change, including cervical effacement and dilatation up to 4cm
  • Established labour = regular painful contractions, and progressive cervical dilatation from 4cm (approx 1cm per hour in nulliparous, 2cm per hour in multiparous) – recommended to have continuous one to one care from midwife.
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10
Q

What is the second stage of labour?

A
  • From full dilation to delivery

* Descent, flexion and rotation –> extension as head delivers

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11
Q

What are the two stages of the second stage of labour?

A

o Passive stage = From full dilation until head reaches pelvic floor and woman experiences desire to push. Rotation and flexion. Allow maybe an hour or two of this.

o Active stage = When mother is pushing. Once the cervix is 10cm dilated, the head moves down the pelvis and applies pressure to the pelvic floor and causes an irresistible urge to bear down (epidural analgesia may prevent this)

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12
Q

Other points about second stage of labour?

A
  • Woman gets in most comfortable position (not supine) and pushes with contractions –> foetus delivered, on average, after 40 minutes (nulliparous) or 20 minutes (multiparous).
  • If >1 hour, spontaneous delivery becomes decreasingly likely.
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13
Q

What is the third stage of labour?

A

From time of delivery of foetus to delivery of placenta.

  • Uterine muscle fibres contract –> compress blood vessels formerly supplying placenta –> shears away from uterine wall.
  • Lasts about 15 minutes –> blood loss up to 500mL
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14
Q

Active management of third stage of labour?

A

Reduces the risk of post partum haemorrhage and shortens the length of the 3rd stage

o Routine use of uterotonic drugs (i.e syntometrine) – can increase N+V.

o Deferred clamping and cutting of the cord (>1 min) – evidence that baby benefits from few minutes of maternal circulation – reduces risk of anaemia in baby in next 6 months.

o Controlled cord traction (apply counter-pressure just above the pubic bone to guard the

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15
Q

Physiological management of third stage of labour?

A

o No routine use of uterotonic drugs

o No clamping of the cord until pulsation has ceased

o Delivery of the placenta by maternal effort.

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16
Q

What are the main causes of foetal damage during labour?

A
  1. Foetal hypoxia (distress) = hypoxia that might result in foetal damage or death if not reversed or the foetus delivered urgently
  2. Infection/inflammation in labour
  3. Meconium aspiration –> chemical pneumonitis
  4. Trauma (rarely spontaneous, more commonly due to obstetric intervention)
  5. Foetal blood loss
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17
Q

What foetal monitoring is warranted in low risk labour?

A

Intermittent auscultation (sonicaid/Doppler/Pinard’s)

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18
Q

What foetal monitoring is warranted in high risk labour?

A

Continuous monitoring (i.e. CTG cardiotocograph)

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19
Q

How often is FHR auscultated in labour?

A
  • Auscultated every 15 minutes in first stage, every 5 minutes in second stage – for 60s after a contraction.
  • If abnormalities detected –> CTG
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20
Q

What is cardiotocography?

A
  • Records FHR on paper (from transducer on abdomen or clip/probe in vagina on foetal scalp)

Also records uterine contractions

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21
Q

When is scalp electrode indicated in CTG?

A

poor contact with abdominal transducer, high BMI, twins, abdominal scarring.

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22
Q

Problem with CTG?

A

False positive rate = high –> confirmation of hypoxia should be made by FBS if CTG concerning.

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23
Q

Mnemonic for interpreting CTG?

A

DR C BRAVADO

DR – defined risk 
C – contractions 
BR – baseline rate 
A - accelerations 
VA - variability 
D - decelerations 
O – overall impression (normal/reassuring, non-reassuring, abnormal)
24
Q

CTG - how often should there be contractions? Do you want accelerations or decelerations with contractions?

A

o 4-5/10 min in labour

o Accelerations with movements/contractions = reassuring

25
Q

CTG - what should baseline rate be?

A

100-160 bpm

26
Q

CTG - what should variability be?

A

5bpm or more – find a bit that doesn’t have spikes.

27
Q

CTG - what should accelerations be like?

A

Rise of >15bpm for 15s – good! Absence not necessarily bad

28
Q

CTG - what kind of decelerations are there?

A

o Early – synchronous with contraction – not concerning.

o Late – after contraction completed – foetal hypoxia.

o Variable – vary in timing – cord compression –> hypoxia.

29
Q

CTG - if decelerations are variable how are they categorised?

A

Typical - <60s + <60bpm

Atypical - >60s or >60bpm – broad and long, take a long time to get back to baseline.

30
Q

If a CTG is concerning, what is management?

A
  • Change maternal position – Left lateral – reduces aortocaval compression –> ↑CO
  • Give fluids - ?dehydrated – pregnancy is very
    dehydrating
  • Foetal scalp stimulation – new NICE 2014
  • Foetal blood sample (FBS)
  • Delivery
31
Q

Foetal blood sample? Benefits and drawbacks?

A
  • If worried about CTG and delivery not imminent – CTG has poor positive predictive value so this is to confirm whether to deliver. FBS = 100% accurate.
  • Invasive procedure, but Immediate/accurate result
  • Must be at least 3cm dilated
32
Q

Interpretation of FBS?

A

o >7.25 = normal – do nothing

o 7.20-7.25 = borderline

o <7.20 = deliver!

33
Q

What is a partogram? What does it record?

A

o Cervical dilatation and descent of the head

o Frequency (and strength) of contractions

o Foetal heart rate

o Liquor colour

o Drugs given

o Maternal observations (Pulse, BP, urine (volume, protein, ketone/glucose), temperature)

34
Q

What causes pain during first stage of labour? Describe it? How is it transmitted?

A
  • Uterine contraction
  • Dilatation of the lower segment of uterus and cervix
  • Visceral pain (colicky, poorly localised)
  • Pain carried via T10 to L1 roots
  • Pressure on pelvic structures causes pain with afferetns via L2-S1 roots
35
Q

What causes pain during second stage of labour? Describe it? How is it transmitted?

A
  • Pain of first stage continues
  • Dilatation and pressure on pelvic organs and pelvic floor structures
  • Pudendal nerves - S2, S3, S4 roots
  • Somatic pain because somatic nerves - sharp, well localised
36
Q

What factors affect pain during labour

A
  • Position of baby (Transverse/breech, Position of head – pressure on pelvic structures/perineum –> more pain in groin).
  • Size of baby
  • Pelvic anatomy
  • Strength of contraction
  • Complications – APH, uterine rupture, trauma
  • Previous experience & expectations
  • Other factors – anxiety, fear of pain, social factors, educational background, etc.
37
Q

Non-pharmacological methods of pain relief during labour?

A
  • Antenatal information and preparation
  • Support from a birthing partner
  • Hypnosis
  • Massage
  • TENS
  • Acupuncture
  • Hydrotherapy (birthing pool)
  • Aromatherapy
  • ‘Placebo’ intradermal injections (water or saline)
38
Q

Pharmacological (inhalational) methods of pain relief during labour? (side effects etc)

A
  • Inhalational – Entonox (nitrous oxide)

o Significant but incomplete analgesia o Quick onset and offset
o Side effects = include dizziness, nausea and amnesia

39
Q

Pharmacological (opioids) methods of pain relief during labour? (side effects etc)

A
  • Codeine, Pethidine, Diamorphine, Morphine, Fentanyl, Alfentanil

o IM/IV – IM has less effect on blood pressure.
o Incomplete analgesia
o Sedation, N+V, respiratory depression

40
Q

Pharmacological (non-opioids) methods of pain relief during labour? (side effects etc)

A

Paracetamol

41
Q

Regional anaesthesia during labour?

A
  • Lumbar epidural
  • Spinal
  • Combined spinal/epidural
42
Q

When would regional anaesthesia be preferred in labour?

A
  • Advanced labour
  • Perineal pain
  • Re-siting epidural
43
Q

Process of spinal? Benefits? When would it be the method of choice?

A
  • Local anaesthetic –> through dura –> into CSF
  • Rapid –> short-lasting but effective analgesia
  • Method of choice for caesarean section or mid-cavity instrumental delivery
44
Q

Complications of spinal?

A

o Hypotension

o ‘Total spinal’ – very rare

45
Q

Process of epidural?

A
  • Local anaesthetic +/- opiates into epidural space (between L3/L4) –> epidural catheter à infused continuously or ‘topped up’ intermittently.
  • Complete sensory and partial motor blockade from upper abdomen downwards
46
Q

Advantages of epidural?

A

o Only method that can make woman pain-free

o Can reduce blood pressure in hypertensive women if labour is long

o Can abolish pre-mature urge to push

o Analgesia for instrumental delivery/caesarean section

47
Q

Disadvantages of epidural?

A

o Increased midwifery supervision – check BP/pulse regularly

o Women is bed-bound à pressure sores

o Reduced bladder sensation –> urinary retention

48
Q

Immediate complications of epidural?

A
  • Failure
  • Inadvertent IV injection –> convulsions/cardiac arrest (rare)
  • ‘Total spinal anaesthesia’ – inadvertent injection of LA into CSF + progression up spinal cord –> respiratory paralysis
  • LA toxicity
49
Q

Delayed complications of epidural?

A
  • Spinal tap – inadvertent puncture of dura –> CSF leakage and severe headache (post-dural puncture headache – PDPH)
  • Infection
  • Haematoma
  • Neurological damage
50
Q

Contraindications to epidural?

A

o Absolute = sepsis/local infection, anticoagulation/coagulopathy, active neurological disease, hypovolaemia, spinal abnormalities, cardiac outflow obstruction

o Relative = spinal surgery, massive haemorrhage

51
Q

Myths about epidural?

A

o Epidural prolongs labour

o Increases incidence of caesarean section – however instrumental delivery more common

o Causes chronic backache

52
Q

Place of birth in labour?

A

Low risk women and their babies are as safe in midwifery units as they are in obstetric units. Home birth is also as safe for multips, but the likelihood of a poor outcome is slightly higher for primips

53
Q

Support in labour?

A

Evidence suggests that women who receive continuous support in labour are more likely to have a spontaneous vaginal delivery, use less analgesia and have a more satisfying experience

54
Q

Eating/drinking in labour?

A

o Encourage women to drink throughout

o Light meals when desired (unless had opiates or develops risk factors increasing chance of a GA)

55
Q

Bladder care in labour?

A

o Encourage women to pass urine regularly

o May need a catheter if unable (e.g. epidural)

56
Q

Observations in labour?

A

o Vital signs, urine analysis

o Vaginal loss – colour of liquor (amniotic fluid), fresh blood

o Contractions

4th Year GOSH (23 decks)

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