Labour

Question 1

Define Labour

Answer 1

Labour = progressive effacement and dilatation of the cervix in the presence of regular uterine contractions (can sometimes have one without the other)

Question 2

Define Delivery, Show, SROM, ARM, Gravidity, Parity and Braxton Hicks Contraction

Answer 2

Delivery = expulsion of the foetus and placenta

Show = cervical mucus plug

SROM = spontaneous rupture of membranes, can precede labour -10%

ARM = artificial rupture of membranes

Gravidity = total number of pregnancies including present

Parity = the state of giving birth (>24 weeks or >500g)

Braxton Hicks contraction – contractions that do not dilate the cervix

Question 3

Which hormones are involved in Labour and what do they do?

Answer 3

Increase of oestrogen in relation to progesterone allows muscles and soft tissue to begin contractions and stretching in response to oxytocin pulsatile release. Oxytocin (posterior pituitary) and prostaglandins (placenta, decidua, myometrium and membranes) induces contractions and stretching of the uterine smooth muscles increases contractility creating a positive feedback loop.

Cervical softening due to oestrogen, relaxin and prostaglandins breaking down connective tissues, this allows effacement and dilatation.

Question 4

Where are contractions the strongest in the uterus?

Answer 4

Contractions are stronger towards the fundus.

Question 5

What is special about contractions of the uterus during Labour?

Answer 5

Myometrium doesn’t relax fully after contractions – contraction and retraction.

Question 6

What does the 1st stage of Labour involve and how long does it normally take?

Answer 6

Latent phase: regular contractions 3-4 times every 10 minutes up to 3cm dilatation.
Active phase: from 3cm to 10cm dilatation.
Expect 0.5-1cm dilation per hour.

Nulliparous - 8.25 hours

Multiparous - 5.5 hours

Question 7

What does the 2nd stage of Labour involve and how long does it normally take?

Answer 7

Fully dilated to birth of the baby
Nulliparous - 1 hour
Multiparous - 0.25 hours

Question 8

What does the 3rd stage of Labour involve and how long does it normally take?

Answer 8

From when the baby comes out to when the placenta comes out.
Nulliparous - 0.25 hours
Multiparous - 0.25 hours

Question 9

How is the 3rd stage of Labour actively managed

Answer 9

3rd stage – active management

1. IM syntometrine to reduce bleeding and reduction in length of 3rd stage. Ergometrine should not be given in the presence of hypertension and it causes more nausea and vomiting.
2. Controlled cord traction
3. Deferred clamping of the cord over 1 minute after delivery but less than 5 minutes (increases haematocrit levels in neonate).

Question 10

Why is active management required

Answer 10

Active management reduces haemorrhage, the need for transfusions and the length of the 3rd stage of labour.

Question 11

When do women get the urge to push?

Answer 11

After 10cm dilatation what happens next will depend on if they have had a baby before and what analgesia they have taken. Normally at this point there will be an overriding urge to push and after an hour of pushing we would expect the baby to be born.

Question 12

How do epidurals affect the way the 2nd stage of Labour happens?

Answer 12

If they’ve had an epidural, then they won’t get that urge to push. If baby is happy leave the contractions to push the baby as far as possible then an hour of active pushing.

Question 13

What are the 3 factors affecting labour?

Answer 13

The passage, the powers (contractions) and the passenger.

Question 14

What are the parameters of the passage?

Answer 14

Pelvic inlet >11cm from sacrum to top of pubic symphysis
Mid cavity = 12cm
Outlet = 10-11.5cm end of coccyx bottom of pubic symphysis

Question 15

How does the baby interact with the pelvic inlet?

Answer 15

Pelvic inlet – baby looks to the side. Then rotation occurs in the mid cavity so the baby looks down towards the mum’s bottom as it passes through the outlet. The Bony pelvis doesn’t cause obstruction much unless there has been disease causing malformation.

Question 16

How can the birth canal soft tissues affect Labour?

Answer 16

Lower uterine segment, Cervix, Vagina, Vulva, Pelvic floor and Perineum. FGM and treatment for cervical cancer can sometimes lead to problems here. Perineum may appear to prevent baby from passing and lead to tear – episiotomy bay be indicated.

Question 17

How do factors of the passenger affect Labour?

Answer 17

Lie – longitudinal, oblique and transverse

Presentation – part of the foetus lowermost in the uterus – cephalic, vertex, brow, face, breech and shoulder. Denominator is the part of the foetus used as a reference point to describe position in maternal pelvis (occiput, mentum, sacrum and acromion)

Position – relation of the foetal denominator to the maternal pelvis

Passenger can mould the bones of the cranium because of the fontanelles to attempt to fit through the pelvis.

Question 18

How can you tell the difference between the anterior and posterior fontanelle of the baby?

Answer 18

Posterior fontanelle looks like a v shape, anterior fontanelle looks like a cross

Question 19

How can we assess how hard the passenger is working to pass through the passage?

Answer 19

If the bones are apart – no moulding
Bones touching - +1
Overriding and can be pushed apart= +2
Over riding and can’t be pushed apart = +3

If 3+ and caput (swelling) then baby working very hard, probably some sort of obstruction and vaginal delivery may not be an option anymore.

Question 20

How do you work out whether a babies head has engaged with the mothers pelvis or not?

Answer 20

Engagement of the foetal head in the pelvis in a transverse position (measured by the number of fifths you can feel between pubic symphysis and babies head). Any less than 2/5ths = engaged.

Question 21

How does the babies position change as it is birthed?

Answer 21

Flexion of the head so its chin is on its chest – costotransverse

Internal rotation so occiput is anterior and baby faces mother’s bottom – occipitoanterior.

Extension of head and crowning until head is delivered then head rotates to face side again

As the baby passes around the pubic symphysis it’s body will externally rotate to face the inside of mum’s thigh to allow the shoulder through. (if this doesn’t happen could be shoulder dystocia).

Question 22

How can we monitor the mother during Labour?

Answer 22

Normal Obs including temperature
Hydration
Analgesia – oral to epidural
Antacids
Bladder care – need to be voiding regularly and if epidural then catheter check for proteins and ketones every 4 hours
Position – shouldn’t be flat on back in case it compresses the great vessels and leads to hypotension
VE every 4 hours

Progress
Contractions, cervical dilatation (expect 1-0.5cm per hour) and descent of presenting part. Check perineum for tears

Question 23

How can we monitor the baby during Labour?

Answer 23

Foetal heart monitoring
Colour of Liquor

All of this shown on a Partogram – visual representation of the observations

Question 24

What the most important thing to do to reduce pain and fear from the mother during Labour?

Answer 24

Education regarding what to expect during labour helps to reduce fear and so pain. One birthing companion is usually recommended.

Question 25

What Analgesic options are available during Labour?

Answer 25

Entonox or Nitrous oxide or gas and air – 50:50 mix of oxygen and nitrous oxide. Self-administered during contractions. Short half life and can sometimes cause feeling faint, nausea and vomiting.

Pethidine – works in 15-20 minutes and given with an antiemetic. However, if given within 2 hours of delivery it can cause neonatal distress and naloxone may be needed. May interfere with breast feeding.
Diamorphine – sometimes used but may cause neonatal respiratory distress. May interfere with breastfeeding.
Meptazinol – another opioid that’s thought to cause less respiratory distress. Onset after 15 mins and lasts 2-7hours

Epidural

Question 26

Describe an Epidural

Answer 26

Consent should ideally be gain antenatally due to the problems of informed consent during labour. Within the epidural space lie the nerve roots. Cover pain fibres from T10 to S5.

Question 27

What are the advantages, disadvantages and contraindications of an epidural for delivery?

Answer 27

Advantages:
Effective analgesia, can be topped up for surgery, provides effective post op analgesia and can be used to aid blood pressure control in pre-eclampsia.

Disadvantages:
Failure, incomplete block and hypotension. Rare but more severe: respiratory depression, epidural abscess, haematoma or nerve damage.

Contraindications:
Sepsis, local infection, coagulopathy, raised intracranial pressure, LMWH within the last 12 hours and haemorrhage and CV instability/hypovolaemia.

Question 28

What is the difference between a spinal and a combined spinal epidural

Answer 28

Note spinal anaesthesia is a one-off injection and usually used for most LSCS. Combined spinal epidural anaesthesia gives quick pain relief and has the option to be topped up later on if there is potential for extended surgery e.g. placenta praevia.