Mechanism and Management of Labour Flashcards
How many weeks gestation is considered ‘term’?
37-42 weeks
What happens to the cervix as labour begins?
- Cervical ripening occurs at the end of pregnancy
- At term, cervix undergoes hypertrophy and an inflammatory-type reaction occurs
What are Braxton-Hicks?
Contractions that increase in frequency and amplitude as labour begins
Describe the first stage of labour
- 4cm to full dilation
- Latent Phase = painful contractions and cervical effacement
- Active Phase = regular painful contractions and cervical dilation
- Transitional Stage = towards end of 1st stage, change in behaviour (panic, fear, nausea, heavy show, shivering, urge to push)
How long is the 1st stage of labour?
Nulliparous = avg. 8h, max. 18h Multiparous = avg. 5h, max. 12h
Describe the second stage of labour
- Full dilation to delivery
- Passive Phase = begins at full dilation prior to/ in absence of involuntary expulsive effort
- Active Phase = begins when baby is visible and involves maternal effort, pH of foetal blood decreases which increases risk of foetal hypoxia
How long is the 2nd stage of labour
Nulliparous = avg. 3h Multiparous = avg. 2h
Describe the third stage of labour
- Delivery to expulsion of placenta
- Common complication = haemorrhage
- Clamping cord should be delayed for over 1 min to increase neonatal iron stores
What are the signs of placental separation?
- Gush of vaginal blood
- Lengthening of umbilical cord
- Rise in uterine fundus
Describe the management of the 3rd stage of labour
- Routine use of uterotonic drug (Syntocinon or Syntometrine)
- Controlled cord traction
- Clamping and cutting of cord
How long is the 3rd stage of labour?
Active management = 30 mins
Physiological management = 90 mins
What are the normal stages of labour?
- Descent
- Flexion
- Internal rotation of head
- Extension
- Restitution
- Internal rotation of shoulders
- Lateral flexion
What is extension?
Foetal head escapes under the symphysis pubis and crowning occurs
What is restitution?
Head is delivered and rotates slightly externally
How do the shoulders rotate internally?
Anterior shoulder rotates forwards to sit under symphysis pubis in AP position
What is lateral flexion?
Anterior shoulder slips under pubic arch and over perineum - remainder of body born by lateral flexion through 3 pelvic planes (curve of carus)
What symptoms suggest that the woman should go in for an evaluation of labour?
- Possible rupture of membranes
- Regular contractions
- Vaginal bleeding
- Severe back, abdominal or pelvic pains
What observations should be taken during labour?
- Temp = 4 hourly
- BP = 4 hourly
- Pulse = hourly
- Freq. of contractions = 1/2 hourly
- Document freq. of emptying bladder
- Urinalysis and abdominal palpation = initial assessment
When should foetal heart auscultation occur?
1st stage = intermittently after most recent contraction every 15 minutes for 60 seconds (palpate maternal pulse to differentiate HRs)
2nd Stage = intermittently after most recent contraction every 5 minutes for 60 seconds
When should continuous electrical foetal monitoring be performed?
- Meconium stained liquor
- Abnormal foetal HR
- Maternal pyrexia (increased temp/ fever)
- Fresh vaginal bleeding
- Oxytocin
- Mother requests it
What is considered an abnormal foetal heart rate?
> 160
<110
How should the midwife assess progress of labour?
- Strength and frequency of contractions
- VE every 4 hours
What are the 3 factors that influence progress?
- Power
- Passenger
- Passages
How does power influence progress of labour?
Uterine contractions
- Established labour = 4 in 10 mins
- Delivery can be achieved with less uterine activity - don’t measure progress by contractions alone
- Influenced by epidural anaesthesia, tocolytics and sedation
How do contractions affect heart rate?
More than 5 contractions in 10 mins = contractions compromise uteroplacental circulation = not enough oxygen = hyperstimulation = tachysystole
How does the passenger influence progress of labour?
- Progress influenced by foetal size and position
- Abdominal palpation required to access descent of presenting part
- Cervical assessment provides information about station of presenting part in relation to ischial spines
How do the passages influence progress of labour?
- Abnormality may cause delay
- Cephalopelvic disproportion = occurs with normal proportions of pelvis vs. macrosomic foetal head
- Rigid perineum may cause delay (may require episiotomy)
What are the NICE guidelines for delayed 1st stage of labour?
- Cervical dilation <2cm in 4 hours for 1st labours
- Cervical dilation <2cm in 4 hours or slowing progress for 2nd and subsequent labours
- Descent and rotation of head
- Changes in strength, duration and frequency of uterine contractions
Describe the interventions that should occur in delay of labour in 1st stage
- Support, hydration and effective pain relief
- Amniotomy if membranes are intact 2 hrs after VE
- Oxytocin if delay confirmed 2 hours after VE in nulliparoud
- Multiparous = full examination by obstetrician if delay 2 hours after VE
- If oxytocin required, transfer women to high risk care and cEFM
Describe the interventions that should occur in delay of labour in 2nd stage
- Intervene after 1 hour delay (4h nulli, 3h multi)
- Amniotomy if membranes are intact
- Consider further pain relief
- Examination by obstetrician required if delay is diagnosed
- Review every 15-30 mins
- Consider instrumental delivery/ CS
- NICE do not recommend use of oxytocin at this stage
Describe the interventions that should occur in delay of labour in 3rd stage
- Delay = >30 mins (active) or >90 mins (physiological)
- If physiological delay, commence active management
- If placenta not delivered for further 30 mins, or earlier if there’s bleeding, make assessment and give appropriate analgesia to remove placenta manually
How is 1 to 1 support beneficial?
- Reduction in pain relief requirements
- Less operative intervention
- Improved birth experience
What is a TENS machine and when should it be used?
- Trans-cutaneous nerve stimulation
- Latent phase only
What temperature should a water birth be?
37 degrees C
What are the 2 main types of opiates used in labour?
- Pethidine
- Diamorphine
What effect do opiates/ epidural analgesia have on labour?
- Latent phase may be slowed by them
- They have little/ no effect in active phase
What negative effects can opiates have on the body?
- Drowsiness, nausea and vomiting
- Short-term respiratory depression
- BF interference
What negative effects can an epidural have?
- Slowed 2nd stage
- Increased incidence of operative delivery
What is the preferred posture in labour
- Provide ample space
- Birth pools, mats, cushions, rocking chair, gym balls
- Discourage supine/ semi-supine position in 2nd stage; associated with delayed instrumental delivery
- Squatting increases pelvic diameter by 8mm
- Changing positioning may help labour progress
